ELECRAFT® KX3
ULTRA-PORTABLE
160-6 METER, ALL-MODE TRANSCEIVEROWNER ’S MANUAL

Revision C5, June 16, 2014

Copyright © 2014, Elecraft, Inc.
All Rights Reserved

Contents
Transmit Noise Gate ......................................... 21	
  Transmit Inhibit and External PTT ................... 21	
  Cross-Mode Operation; CW-in-SSB ................ 21	
  Transverter Bands ............................................. 21	
  Special VFO B Displays ................................... 22	  Extended Single Sideband (ESSB) ................... 22	
  Introduction .................................................... 3	  Key to Symbols and Text Styles..........................3	
  Installation ...................................................... 4	  Operating Position ...............................................4	
  Power Supply .......................................................4	
  CW Key/Keyer Paddle ........................................4	
  Headphones and Speakers ...................................5	  Microphone ..........................................................5	  Computer/Control Port (ACC1) ..........................5	  Keyline Out and GPIO (ACC2)...........................5	  Quadrature Outputs (RX I/Q) ..............................5	  Antennas ..............................................................6	
  Grounding and ESD Protection ...........................6	
  Internal Batteries .......................................... 23	
  VFO Friction Adjustment ............................. 24	
  Options and Accessories ............................... 25	
  Firmware Upgrades ...................................... 25	
  
SDR Applications .......................................... 26	
  Remote Control of the KX3........................... 28	
  Control Panel Reference ................................ 7	
  Display (LCD) .....................................................8	  Configuration ................................................ 29	
  Option Module Enables .................................... 29	  Menu Settings ................................................... 29	
  Basic Operation............................................... 9	
  Getting Started .....................................................9	  Band Selection ...................................................10	
  Mode Selection ..................................................10	
  VFOs A and B ...................................................11	
  Incremental Tuning (RIT and XIT) ...................11	  Special VFO B Displays ....................................11	  Receive Settings ................................................12	
  Transmit Settings ...............................................14	
  Transmit and ATU Control................................14	
  Voice Modes (SSB, AM, FM) ...........................15	
  
CW Mode ..........................................................16	
  Calibration..................................................... 31	
  Reference Frequency ........................................ 31	
  Receive Sideband.............................................. 32	
  Transmit Bias .................................................... 32	
  Transmit Gain ................................................... 33	
  Transmit Carrier................................................ 34	
  Transmit Sideband ............................................ 34	
  Menu Functions ............................................ 35	  Troubleshooting ............................................ 44	
  Parameter Initialization (EEINIT) .................... 46	
  Error Messages (ERR nnn) ............................... 47	
  Advanced Operating Features ...................... 17	  Frequency Memories .........................................17	
  Scanning ............................................................17	
  Data Modes ........................................................18	
  Text Decode And Display .................................19	
  Programmable Function Switches .....................19	
  Split and XIT .....................................................19	
  Audio Effects .....................................................20	
  Dual Watch ........................................................20	
  Receive Audio Equalization (RX EQ)...............20	
  Transmit Audio Equalization (TX EQ) .............20	
  SSB/CW VFO Offset.........................................21	
  Digital Voice Recorder (DVR) ..........................21	
  Theory Of Operation ..................................... 49	
  RF Board ........................................................... 49	
  Control Panel (CP) Board ................................. 50	
  KX3 Block Diagram ......................................... 51	
  Glossary of Selected Terms .............................. 52	
  Specifications ................................................ 54	
  Customer Service and Support ..................... 55	
  Index .............................................................. 56	
  2

Introduction
On behalf of our entire design team, we’d like to thank you for choosing the Elecraft KX3.
The KX3 is a compact, 160-6 meter, all-mode transceiver that’s ideal for both new and experienced
operators. Its unique features meet the requirements for home station use, portable, mobile, and evenhand-held operation.
Since the KX3 is a software-defined-radio (SDR), you’ll be able to extend its capabilities using
computer applications, and add new features via free firmware upgrades. But the KX3 is also the only
compact transceiver that combines the flexibility of an SDR with a full-size front panel and display,allowing operation with or without a computer.
Despite its small size, the KX3 can be configured as a fully self-contained amateur station, with aninternal antenna tuner, battery charger, 2-meter or 4-meter module, and attached CW keyer paddle.
These options can be added at any time. Current drain is also very low for a full-featured transceiver,reflecting our commitment to field operation. For mobile and home use, you can boost the KX3’s
output to 100 watts with the optional KXPA100 amplifier. Finally, there’s the PX3 high-performance
Panadapter, which enhances operation by allowing you to see signals even before you hear them.
When it’s time to take on the challenge and adventure of amateur radio, your KX3 will be ready.
73,
Wayne, N6KR
Eric, WA6HHQ

Key to Symbols and Text Styles
Important – read carefully
Operating tip
LSB

Display icon or text.

Enter keypad function.

Lock indicator (applies to VFO or menu parameter)
XMIT

Tap switch function (labeled on a switch)

TUNE

Hold switch function (labeled below a switch; hold for about 1/2 second)

MIC

Function of a rotary control (knob)

OFS / BTap switch function of a rotary control (labeled above a knob)

CLR

Hold switch function of rotary control (labeled below a knob; hold for 1/2 second)

BKLIGHT

Menu entry

3Installation
§

§
§
§

CAUTION

Power Supply

Be careful when plugging in cables. Avoid
applying sideways pressure that might damage
the KX3’s left-side jacks.
Avoid operating in wet conditions (rain,snow, spray, etc.). The KX3 is not waterproof.
Avoid operating at very high temperatures.
The KX3 can be damaged by electrostatic
discharge (ESD). Prior to opening the case,touch a grounded, unpainted metal surface.

For fixed-station use, a low-noise 12-14 VDC
power supply or battery is recommended. (Seelinear and switching power supplies in the
Glossary, pg. 52.) For lightweight portable
operation, the KX3’s internal 8-AA-cell battery
pack can be used. See Internal Batteries, pg. 23.
Maximum power output varies with supply
voltage and other parameters. For full power(10+ watts on most bands), use 12-14 V.
Connect an external power supply or battery to the
9-15 VDC jack (see illustration below). The centerpin is (+). A 2.1-mm power plug is required(Switchcraft S760 or equivalent). On the supplied
power cable assembly, the wire with the white
stripe is (+). Trim the cable to the desired length.

Operating Position
All controls are located on the top of the KX3’s
enclosure. This provides ample space for controls
and display, despite the transceiver’s small size.
Tilt legs are provided in the back to position thecontrols and display for ease of use, as shown
below. Loosen the two rear thumbscrews before
adjusting the legs. Tighten them afterwards.

CW Key/Keyer Paddle
The KX3 has two CW keying inputs:
KEY Jack: This stereo 3.5 mm jack on the left side
can be used with any hand key, keyer paddle, orother keying device, as selected by the CW KEY1
menu entry (see Using the Menu, pg. 9).

To open the enclosure, follow the
instructions on pg. 23 (Internal Batteries). Use
only the method shown.

A stereo plug is required at the KEY jack,even if only the tip contact is being used, as witha hand key.

The KX3 can be conveniently operated with
one hand, in a manner similar to writing in a
notebook. If you’re right-handed, rotate the radio
slightly counter-clockwise (see cover illustration).
If you’re left-handed, rotate the KX3 clockwise.

KXPD3 Keyer Paddle: The KXPD3 is an optional
high-quality keyer paddle that attaches at the frontof the KX3 via two thumb screws. The dot and dashpaddles can be electrically reversed or configured
as a hand key using the CW KEY2 menu entry.
Allen wrenches are supplied for contact adjustment.
4

Computer/Control Port (ACC1)

Avoid using bulky connectors or adaptersthat could put excessive stress on side-panel
jacks. Lightweight cables, preferably with rightangle plugs, are strongly recommended.

The 3.5-mm stereo ACC1 jack allows firmware
updates, configuration, and remote control of theKX3 via a computer. The jack can be connected to
a computer’s USB port via the Elecraft model
KXUSB cable, or to an RS232 port via the model
KXSER cable. (The jack’s tip connection is RX
data from the computer. Ring is TX data to the PC.)

Headphones and Speakers
The 3.5-mm PHONES jack, on the left side panel,accommodates mono or stereo headphones. You
can also plug in one or two amplified (or powered)external speakers here. Mono or stereo plugs can beused. Stereo allows the use of audio effects,
providing an enhanced listening experience (pg.
29).

Elecraft provides two KX3 configuration programs:
KX3 Utility is required for KX3 configuration andfirmware updates (pg. 25). It also provides a
CW/data terminal function.
Our K3 Memory PC application can be used with
the KX3 to set up frequency memories more easily
than with the radio’s memory-store function.

The KX3 includes a small built-in speaker for use
in quiet operating environments. Plugging in
headphones disables the speaker and its amplifier.
(This is an easy way to extend battery life.)

Many logging, contesting, and control programs areavailable from third parties. If the KX3 is not
specifically supported by a given program, try
selecting Elecraft K3 or K2.

Mobile installations: The interior of most vehicles
is too noisy for use with the KX3’s built-in speaker.
One or two amplified mobile speakers can beplugged into the PHONES jack, or you can connect
this jack to your car stereo’s AUX input. Anotheralternative is to use a device that retransmits the
KX3’s audio output in the FM broadcast band.

Keyline Out and GPIO (ACC2)

Microphone

The 2.5-mm stereo ACC2 jack provides a keyline
output (ring contact) and a general-purpose 3-volt
logic signal (tip contact).

The MIC jack is compatible with the Elecraft MH3
hand mic, which provides PTT as well as VFO
UP/DN buttons. For the MH3, set the MIC BIAS
menu entry to O N , and MIC BTN to P T T U P . D N .

The keyline output goes low during transmit, andcan be used for transmit/receive switching of linear
amplifiers and transverters. For keyline voltage andcurrent limits, see Specifications.
The general-purpose signal, GPIO, can be set up forvarious equipment control functions. For example,
it can send band-change information to Elecraft
XV-series transverters. See the ACC2 IO menu
entry for a full list of uses for this signal, as well as
hardware interface requirements.

MH3 Mic Pinout
Sleeve: ShieldRing2: Logic ground

Quadrature Outputs (RX I/Q)

Ring1: PTT/UP/DN
Tip:

The 2.5-mm RX I/Q jack provides quadrature
outputs from the receive mixer (I=in-phase;
Q=quadrature, or 90 degrees out of phase). These
outputs can be used with the Elecraft PX3
Panadapter, as well as with computer-based
software-defined radio (SDR) programs, to extend
the capabilities of the KX3. See SDR Applications(pg. 26).

Mic audio

Using other microphones and headsets: The KX3
is compatible with many headset-mics that haveseparate 3.5-mm plugs for mic audio and receive
audio. You can also use some “mini” mics intended
to plug directly into a laptop computer. Refer to the
MIC BIAS and MIC BTN menu entries to set up
the KX3 for use with your mic or headset.
5Antennas

Grounding and ESD Protection

You can use any resonant antenna having a 50-ohm(approximate) load impedance with the KX3.
Examples can be found in the ARRL Antenna
Handbook and other sources. A simple inverted “V”
or dipole can be very effective.

Connecting the chassis to a driven ground rod canprovide some protection against lightning anddamage due to electrostatic discharge (ESD). Whenused in a building, the rod should also be bonded toother building grounds. Connect the ground (or acounterpoise for a whip or single-wire antenna) tothe KX3 at the thumb screw indicated below, on theright side panel. The back thumb screw on the left
side can also be used.

Antenna jacks: The BNC antenna jack, identified
at right, is used on 160-6 m. The SMA jack shown
is supplied with the KX3-2M/4M module (pg. 25).
The basic KX3 has a hole plug at this location.
Field Antennas: Field operation often calls for
non-resonant, ad-hoc wire antennas. For example,
you might use a single wire of 25’ (7 m) or longer,
tossed in a tree using a fishing weight or large hex
nuts. Another popular field antenna is the short,loaded whip with interchangeable loading coils.

2m
SMA

160-6 mBNC

GroundIf you use a short whip, vertical, or a single
wire, a counterpoise of some kind is necessary(described at right) to carry the return current. No
counterpoise is needed for a dipole, since one halfof the diplole carries return current.
Portable Station Ground: When you’re operatingfrom a temporary location, you can use one or moreradials as a counterpoise. This can simply be a setof wires tied together at one of the KX3’s groundpoints, then laid out on the ground in all directions.
When possible, use at least one 1/4- wavelength
radial for each band used. The length in feet can becalculated from 234 divided by F, where F is theoperating frequency in MHz. If the wires are laying
on the ground, subtract about 20% from theirlength. Random-length (untuned) counterpoisewires can also be used when necessary.

SWR: One measure of how close an antenna is toresonance is its SWR (standing wave ratio). The
KX3 displays SWR in TUNE mode (pg. 14). An
SWR of 1.0:1 (1 . 0 - 1 on the KX3’s display) is
considered a “perfect” match. To ensure safe
operation, the KX3 reduces power if SWR is high.
Using An Antenna Tuner (ATU): An ATU willallow the KX3 to “see” a good match (i.e., a low
SWR) even with non-resonant antennas. This
allows the transmitter to deliver full power, and can
improve receiver sensitivity. An ATU may also
allow one antenna to be used on multiple bands.
You can use an external ATU (e.g., an Elecraft T1
or KXAT100) or internal (e.g., the KXAT3 option,
pg. 25). The KXAT3 stores matching information at
multiple points within each band.

Pedestrian Mobile Ground: The KX3 can be
operated hand-held—even while walking—with ashort whip antenna. Such antennas may provide
acceptable performance in receive mode without aground. However, if you plan to transmit, you’ll
need a trailing ground wire to serve as a minimal
counterpoise and greatly improve your transmitted
signal. This is true even if the KX3 indicates a low
SWR in TUNE mode (without a counterpoise, theSWR reading can be misleading). 13’ is a good
choice for a trailing ground wire. This length isabout optimum on 20 meters, and is usable on 40-6
meters as well, assuming you’re using a multi-band
whip (or an antenna tuner). Small-diameter coax
such as RG-174 works well for a trailing wire
because it resists getting tangled while you walk.

Feedline: You can connect a wire antenna directly
to the KX3 without any coax or other feedline. (Amale BNC to binding-post adapter can be used,such as Elecraft #BNC-BP.) However, manyantennas will function better when their feed point
is well above ground. A multi-band, random-length
antenna can be fed with twin-lead, then connected
to a balun (balanced-to-unbalanced converter, suchas the Elecraft BL1 or BL2), which in turn isconnected directly to the transceiver.

6

Control Panel ReferenceThis section summarizes all KX3 controls. For details, see Basic Operation and Advanced Operating Features.
To Turn Power ON/OFF: Hold both the B A N D - and A T U T U N E switches for 2 seconds. (See ON/OFF label on left side.)
Tap Functions: Tap a switch or knob briefly to activate the function labeled on or above it, e.g. RATE .
Hold Functions: Hold the control for about 1/2 second to activate the function labeled below, e.g. KHZ .
Numeric Keypad: Switches and knobs at lower-left form a keypad (0-9/decimal/enter). Used with F R E Q E N T , etc.

Band Selection

Display, pg. 8

Operating Mode and VFO Setup

B A N D + / B A N D - Band up/down, pg. 10

M O D E Basic mode; A L T Alternate mode (e.g. LSB/USB), pg. 10

R C L / S T O R E Frequency memories, pg. 17

D A T A Data submode, pg. 18; T E X T Text decode setup, pg. 19
A / B VFO A/B swap, pg. 11; R E V VFO/repeater reverse, pg. 11

per-band: tap 1-4; general purpose (00-99): use VFO A
F R E Q E N T Use # keys, thenA), pg. 10; DTMF, pg. 15

S C A N Scan from VFO A to VFO B, pg. 17

B Copy VFO A to B, pg. 11; S P L I T Split RX/TX, pg. 19

R I T / X I T RX/TX offset, 11; P F 1 / P F 2 Prog. function, pg. 19

ON /
OFF

Transmit / ATU Control
M S G / R E C Message play/record, pg 16

Transmit Settings
K E Y E R / M I C WPM, pg. 14; mic gain, pg 14

Offset / VFO B and Misc.
O F S / V F O B RIT/XIT/VFO B, pg. 11

A T U T U N E Start auto antenna tune, pg 14

P W R Set power level, pg. 14, 15

A N T Select ANT 1/2 (KXAT100 opt.), pg. 14

C M P Speech compression, pg. 15 *C L R Clear RIT/XIT offset, pg. 11
R A T E Select 1/10 Hz VFO steps, pg. 11
K H Z Select coarse VFO steps, pg 11

X M I T Enter transmit mode (PTT), pg. 14

P I T C H CW sidetone, pg. 16; FM tone, pg. 15*

T U N E Transmit CW carrier at PWR level

D L Y CW QSK delay, pg. 16; VOX delay, pg. 16*

D I S P Show voltage etc. on VFO B, 11 *(or MENU:TUN PWR level, if lower), pg. 14

V O X VOX/PTT (CW/voice separate), pp. 16, 15

M E N U Use VFO B to select, A to edit

Receive Settings
A F / R F - S Q L Receiver gain control, pg. 12
M O N Monitor & switch tones volume, pg. 12

VFO A, pg. 11

P B T I / I I Passband tuning (I=WIDTH/LO, II=SHIFT/HI), pg 12
N O R M Filter passband normalization (per-mode), pg. 12

P R E Preamp, pg. 13 ; A T T N Attenuator, pg. 13

A P F Audio peaking filter, pg. 13; S P O T CW spot tone, pg. 13

N R Noise reduction, pg. 13 *N T C H Autonotch (SSB) or manual notch (CW), pg. 13 *N B Noise blanking, pg. 13 *C W T CW/DATA tuning aid (uses upper portion of S-meter), pg. 13* To adjust the parameter for this switch function, use the knob immediately above the switch.

7

Transmit LED, pg. 14
Delta-F LED, pg. 11

Display (LCD)
Bar graph, receive mode: Shows RX signal
strength in S-units (S-meter). If C W T is turned
on, the right half of the S-meter becomes a tuningaid (pg. 13). Reducing RF gain adds a moving
reference segment (pg. 12).

VFO Icons:
Shows that a VFO or menu
entry is locked. The TX icon points to the transmit
VFO:
A

Bar graph, transmit mode: Shows antenna
S W R and R F output (pg. 14). In voice modes,
shows C M P (compression) and A L C (mic level)
when mic gain or CMP are set (pg. 15). ALC
scale also used to set DATA audio level (pg. 18).

TX

TX
B

VFO A is the transmit VFO

VFO B is the transmit VFO; see SPLIT

VFO A

VFO B
Filter Passband Graphic: Shows locationof receive filter passband (pg. 12)

Mode Icons
Basic modes (L S B or U S B , C W , D A T A , A M , orF M ) are selected by tapping M O D E . Alternate modes(C W R E V , D A T A R E V , A M - S , F M + / - ) areselected by holding A L T . L S B and U S B are alternatesof each other. In SSB mode, the + icon indicates
ESSB (pg. 22). T indicates FM PL tone (pg. 15) or
CW/DATA text decode (pg. 19).

Filter Icons:
NTCH
I / II
XFIL

Auto or manual notch (N T C H , pg. 13)
Manual notch (N T C H , pg. 13)
PBT filter function (I / I I , pg. 12)
Filter (F L 1 -F L 3 used, pg. 12)

Other Icons:

Automatic RX attenuation in effect (pg. 13)
A T T Attenuator on ( A T T , pg. 13)
P R E Preamp on ( P R E , pg. 13)
A T U ATU enabled ( A T U T U N E , pg. 14)
RIT
RIT on ( R I T , pg. 11)
XIT
XIT on ( X I T , pg. 11)
S U B Dual-watch enabled (DUAL RX, pg. 20)
S P L T Split mode in effect (S P L I T , pg. 19)
RX

CWT
VOX
QSK
NB
NR
ANT

CW/data tuning aid on (C W T , pg. 13)
Message play/rec ( M S G / R E C , pp. 16, 21)
VOX enabled (V O X , pp. 15, 16)
Full break-in CW enabled ( D L Y , pg. 16)
Noise blanker on (N B , pg. 13)
Noise reduction on (N R , pg. 13)
Antenna 1 /2 , KXAT100 (A N T , pg. 25)

8

AF Gain and other Knob Functions

Basic Operation

Each of the four small knobs has a primary functionthat is in effect when you turn on the KX3. For
example, the knob at far left,
AF / RF-SQL ,normally controls receiver AF gain (volume). As
you rotate this knob, the AF gain setting isdisplayed in the VFO B area.

This section describes basic KX3 controls andfeatures. Once you’ve mastered the basics, you’ll beready to explore the Advanced Operating
Features section (pg. 17), which covers built-in
text decode, frequency memories, dual watch andother topics.

Tapping this knob briefly switches to its secondaryfunction, RF gain (squelch in FM mode). Holding
the knob—pushing it for over 1/2 second—switches
to a third function,
M O N (volume setting fortransmit monitor and switch tones).

Getting Started
Before using the KX3, you’ll need to connect a
power supply and an antenna, at minimum. See
Installation (pg. 4) for more details.

The small knobs are also used in conjunction withnearby switches. For example, if you tap D I S P ,rotating the knob directly above it (OFS / VFO B)
will scroll through several special displays,
including time, supply voltage, current drain, etc.

Turning the KX3 On/Off
To turn the KX3 on or off, press and hold theB A N D - and A T U T U N E switches simultaneously
for about two seconds, then release. Left sidelabeling identifies these two switches (see below).
This power on/off method reduces the likelihood ofaccidental activation in a backpack or carrying case.

Using the Menu
The menu is used to tailor the transceiver to youroperating preferences.

Always turn the KX3 off as described above
before turning off or disconnecting any external
power source. This will ensure that your current
VFO settings, etc., are saved.

To access the menu, hold M E N U until the
BKLIGHT (LCD brightness) menu entry appears inthe VFO B area. The parameter, in this case thebrightness level, appears in the VFO A area.
To change the value of a menu parameter, rotate
VFO A (large knob). In the case of BKLIGHT,
rotating the knob will select backlight O N or O F F .
To scroll through menu entries, use the small
knob above the menu switch, O F S / V F O B .
To exit the menu, hold M E N U again.
While in the menu, holding M E N U for about 3
seconds displays usage information about thepresent menu entry. Tap any switch to cancel.

Configuration Menu Functions
Switch T A P and H O L D Functions

Now that you know how to use the menu, you may
wish to review the Configuration section (pg. 29)
to make sure the KX3 is configured properly foryour installed options and operating preferences.

All KX3 switches have two functions:§

Tap to activate the function labeled on a switch,e.g. R A T E§Hold for about 1/2 second to activate thefunction labeled below a switch, e.g. K H Z

There are also a number of calibration steps
performed on your KX3 at the factory (for both kits
and assembled radios). See Calibration, pg. 31.

9Band Selection

Mode Selection

The KX3 covers the 160-6 m amateur bands.
Characteristics of each band are summarized below.
For further information, see the ARRL band plan:

Each mode is described briefly below. Latersections cover each mode in detail.
Tap M O D E one or more times to select SSB, CW,
AM, or FM mode. A L T selects alternate modes,
such as CW reverse. Tap D A T A to select data
mode. To select a data sub-mode, tap D A T A again,
then rotate
OFS/VFO B .

http://www.arrl.org/band-plan-1
You can change bands using B A N D + or B A N D - ,memories (pg. 17), or F R E Q E N T (see below).

SSB (single sideband, pg. 15) is a narrow-banded
voice mode that conserves space in crowded band
segments. It’s the most popular mode overall. LSB(lower sideband) is usually used on 160, 80, and 40
meters, while other bands use USB (upper
sideband). You can override the default using A L T .

You can remove bands you don’t use from theB A N D + / - switch group using MENU:BND MAP.
Band
(m)

Range
(MHz)

Best
DX

Other
Characteristics

160

1.8-2.0Night80

3.5-4.0Night60~5.3-5.4

Night

40

7.0-7.3

Night

30
20

10.0-10.15
14.0-14.35

Both
Both

17

Day

15

18.06818.168
21.0-21.45

1210

24.89-24.99
28.0-29.7

Day
Day

6

50-54
(VHF)

Both

Challenging “Top Band”; highpower often used to counter noise
Excellent regional band; many
CW and SSB nets; AM ~3.870
Shared with government services;
power level and modes restricted
Excellent local CW/SSB band byday; QRP & data modes, 7.03-7.04
DX possible anytime; no contests
Very popular DX & contest band;many nets on SSB; Data modes:
PSK31 ~14.070; RTTY ~14.085
Long-haul DX band; no contests;“HF Pack” at 18.1575 (often QRP)
DX/contest band; low power very
effective when band is open
Excellent DX band; no contests
Great DX band when open; CW
beacons 28.2-28.3; FM 29.6-29.7
Active night or day during rare
DX openings; some FM repeaters

Day

CW mode (pg. 16) uses on-off keying of thecarrier. CW requires very little bandwidth,
providing a high signal-to-noise ratio that’s ideal
for low-power (QRP) use. It’s also a popular modefor DXing and contests. Holding A L T switches to
C W R E V (CW reverse), reversing the received
sideband in CW mode from LSB to USB. This may
reduce the level of interference (QRM).
AM mode (amplitude modulation, pg. 15) ischaracterized by its good fidelity . It is much lesspower-efficient than SSB. AM amateur operation isoften found on 160, 80, 40, and 10 meters.
FM mode (frequency modulation, pg. 15) is mostoften used for local communications, and can befound on 10 m and up (see ARRL band plan). The
KX3 supports simplex and repeater operation,
including tone encoding. Many repeaters can befound on the 2-m band (144-148 MHz), which iscovered by the KX3-2M option module (pg. 25).

Direct Frequency Entry
The controls below function as a numeric keypad(see 0 - 9 labels) when used with F R E Q E N T .

If you don’t plan to operate in AM or FM
modes, you can turn them off individually using the
AM MODE and FM MODE menu entries (pg. 35).
DATA modes (Advanced Operating Features, pg.
18) typically use a computer connected to thetransceiver to send/receive text. Although SSB
modes can also be used for this purpose, the KX3’saudio-based data modes (D A T A A and A F S K A )optimize settings for data rather than voice.

First, tap F R E Q E N T . Then enter up to three
MHz digits, optionally followed by a decimal point( A T U T U N E switch) and up to three kHz digits.
Next tap. ( M S G switch) to accept, or any
other switch to cancel. Examples:
14.255 MHz: F R E Q E N T
7.000 MHz: F R E Q E N T

1 4 . 2 5 5
7.

The KX3 also has two built-in data modes that
don’t require a computer: F S K D (narrow-shift
RTTY) and P S K D (PSK31). These modes use the
KX3’s display for receive, and a keyer paddle fortransmit, converting the CW you send into data.

. .

.
10

VFOs A and B

VFO A and B swap: Tap A / B to exchange VFO
frequencies, modes, and all other settings.

The KX3 provides two VFOs (see glossary, pg. 52).
Use of VFO B is optional. The VFO knobs arelocated in the area shown below. Each VFO has
independent frequency, mode, and filter settings.

VFO A/B temporary reverse: Sometimes you’ll
want to swap the VFOs temporarily to look for an
open transmit frequency when operating split (pg.
19). In this case, hold R E V . The VFOs will beswapped back as soon as you release the switch. In
FM mode, R E V swaps receive/transmit frequencies
and the repeater offset direction (pg.15).

Incremental Tuning (RIT and XIT)
RIT, or receive incremental tuning, provides ameans of adjusting the receive frequency without
affecting your transmit frequency. This control issometimes called a clarifier since it can be used totune in SSB voice signals. But RIT can also be used
in CW and DATA modes, in the event that a station
calls you slightly off-frequency. RIT and XIT use
the tuning rate (1/10 Hz) selected for the VFOs.

VFO A normally controls both the receive andtransmit frequency. Most contacts occur between
stations tuned to about the same frequency, so if
you use VFO A to tune in a signal clearly, there’s agood chance they’ll hear you when you transmit.

XIT, or transmit incremental tuning, adjusts thetransmit frequency without affecting the receive
frequency. See Split and XIT, pg. 19.

VFO B can serve as a holding register for a second
frequency of interest, then swapped with VFO A as
needed (see A / B at right). To tune VFO B
directly, first make sure the B LED above the knob
is lit. If not, tap theO F S / V F O B knob. Also see
S P L I T (pg. 19) and Dual Watch (pg. 20).

∆ F (Delta-F) LED : Whenever an RIT or XIT
offset is in effect, or during split operation, the ∆ F
LED turns on as a reminder that your receive andtransmit frequencies are different.
To use RIT or XIT: First, tap R I T or X I T . Thisturns on the R I T or X I T icon on the display, as wellas the O F S LED (above
O F S / V F O B ). Thenadjust the offset using
OFS/VFO B .

Tuning rates: Tapping R A T E selects either 1 Hz
or 10 Hz VFO tuning rate. Holding K H Z selects a
per-mode coarse tuning rate (see MENU:VFO
CRS, pg. 30). SSB stations often align on 0.5 or 1.0
kHz boundaries. AM broadcast stations are
typically spaced at 5, 9, or 10 kHz.

To zero the RIT/XIT offset: Hold C L R .
You can still use theO F S / V F O B control
to tune VFO B, even if RIT or XIT is turned on.
Just tap the knob to switch its function back to VFO
B (the B LED will turn on). The RIT/XIT icons on
the LCD will retain their current states.

To lock VFO A: Hold K H Z for about 3 seconds.
Tap R A T E to unlock. To lock VFO B, swap it withVFO A first, lock it, then swap back.
You can use theO F S / V F O B control totune VFO A in coarse steps, while the VFO A
control itself is still set up for fine steps. First, makesure the O F S LED is lit (tap the O F S / V F O Bknob one or two times). RIT and XIT (described atright) must also be turned off. To disable the VFO
offset-tuning feature, see MENU:VFO OFS.

Special VFO B Displays
The VFO B display area can show several usefulparameters. To see these, tap D I S P , then rotate theO F S / V F O B control. This will cycle throughseveral displays including time, supply voltage,current drain, power amplifier temperature,synthesizer temperature, audio voltmeter, andrelative audio (dBV) meter. For details see pg. 22.

To copy VFO A’s frequency to VFO B: Tap
A
B . Tapping a second time copies VFO A’s
mode and filter settings to VFO B as well.
11

Receive Settings

Passband Tuning Functions (PBT I/II)

The RX control group, shown below, is used to set
up the KX3’s receiver. Directly above thesecontrols is the filter passband graphic, which shows
the shape and position of the receiver’s passband.
This determines what pitch range you’ll hear.

The P B T I / I I control is used to shape the KX3’s
receive filter passband. In general, a narrowpassband reduces interference (QRM) and noise(QRN), while a wider passband improves fidelity.
In voice modes, tapping
P B T I / I I normallyselects low-cut (function I) or high-cut (function
II). These functions remove low- or high-pitchedinterfering signals. Examples of filter graphic
segments that might turn off as the result of a lowcut or high-cut are shown in light gray below. (Toselect width/shift for SSB, instead, use PBT SSB.)
Low-Cut

High-CutIIIIn CW and DATA modes, the passband functions
are width (I) and shift (II). The effect of thesefunctions is illustrated below. Reducing the widthor shifting the passband may attenuate aninterfering signal above or below the desired one.

AF Gain, RF Gain, and Squelch
The A F / R F - S Q L knob normally controls
receiver AF gain. Tapping the knob switches its
function to squelch (FM mode only) or RF gain(all other modes). Also see “AF, RF, and IF” in theglossary (pg. 52).

Width

Shift
I

II

Holding
P B T I / I I normalizes the passband(N O R M ), centering it and setting it to the default
width for the current mode. Two small "anchors"appear at the left and right ends of the graphic.
Holding NORM again restores the previous
passband settings.

RF gain is normally left at maximum (- 0 d B ).
Reducing RF gain may be useful in some strongsignal conditions. If you reduce RF gain more thana few dB, a separate segment of the S-meter turns
on as a reminder. The segment used varies with theamount of RF gain reduction. (A high S-meterreading may hide the RF gain indicator segment.)
Squelch is used to mute the receiver until a signal
appears. It is most often used with repeaters. The
control adjusts the signal threshold required forsquelch to “open,” unmuting the receiver.

Roofing Filters (XFIL)The X F I L icons, to the right of the filter passband
graphic, show whether the optional roofing filters(F L 2 , F L 3 ) are in use. These filters, located on the
KXFL3 option module, can reject strong nearby
signals that might interfere with weaker ones.

Voice Monitor/CW Sidetone Level (MON)Holding
A F / R F - S Q L temporarily switches its
function to M O N , which controls how much ofyour own signal you hear when transmitting.
Transmit monitor setup is covered on pg. 14.

When F L 1 is indicated, the roofing filters are
bypassed, and the pre-DSP bandwidth is about 15
kHz. F L 2 (3000 Hz) and F L 3 (1000 Hz) areautomatically selected, when possible, based on theoperating mode and settings of the filter controls.

Switch activation tones, if used, have the same
volume level as the CW sidetone (as set in CW
mode using M O N ). Switch tones can be set tooff, on, or Morse code characters at various speeds
using the SW TONE menu entry.

Dual watch (MENU:DUAL RX) also uses FL1,
overriding the normal per-mode filter selection.

12

Preamp and Attenuator

CW/DATA Tuning Aid (CWT)P R E turns on the RF preamp. It should be used
only when signals are very weak. Preamp gain canbe set on a per-band basis using MENU:PREAMP.
A T T N turns on the 15-dB RF attenuator, which canprotect the receiver from strong interfering signals.

Accurate tuning of received signals is required
before you call a station, or when you’re using
built-in text decode (T E X T , pg. 16). Tuning can bedone by ear. But CWT, in conjunction with AutoSPOT (below), can often tune in stations for you.
When you hold C W T , the upper half of the S-meter
becomes a receive VFO tuning aid for CW andsome data modes.

The KX3 will automatically reduce receive gainin the presence of very strong signals. The receive
overload icon (R X ) will alert you to this (pg. 8).

A CW signal will appear as a single bar in the CWT
display, as shown in the left example below. Use
VFO A to tune in the signal until the bar directly
under the CWT pointer is turned on. A narrow filter
width is recommended (100-400 Hz). This display
also applies to PSK31 (PSK D, pg. 18).

Noise Reduction
Noise reduction (NR) removes random backgroundnoise (hiss or static). It has a characteristic “hollow”
sound. Higher settings may attenuate weak signals.
Holding N R turns on noise reduction and displays
its setting, which can be adjusted using the knob
above the switch. Tap any switch to exit the setting
display. Hold N R again to turn noise reduction off.

CW and PSK31

RTTY

CWT

CWT

S1 3 5 7 9Noise Blanking

SWR

Noise blanking can eliminate repetitive noise suchas that from power lines, appliances, and vehicle
ignitions systems. Use the lowest effective setting
to avoid unwanted signal/noise interaction.

2 3

S1 3 5 7 9

RF

50

100

SWR

2 3

RF

50

100

In RTTY or radioteletype modes (FSK D, AFSK A;
pg. 18) mark and space tones are represented bythree bars on either side of the CWT pointer. If no
RTTY signal is present, you’ll see the “ghosting”
effect shown above. As you tune in an RTTY
signal, the number of solid bars will increase. Keeptuning until you see a rough balance between left
and right solid bars during an RTTY transmission.

N B turns on the noise blanker. The NB setting isadjusted in the same way as NR (see above).

Audio Peaking Filter (APF)
A P F turns on a very narrow filter that improves
copy of very weak CW signals buried in noise. The
filter graphic changes to that shown below. With
APF on, PBT function I still adjusts the overall
passband width; function II tunes the APF center
pitch. 1-Hz VFO tuning is automatically selected.

SPOT and Auto-SPOT

Notch Filtering

To use auto-SPOT: First turn on C W T . Tapping
S P O T will then automatically tune in a received
signal that falls within the CWT display range.

You can use S P O T to manually tune in a CW or
PSK31 signal, matching it to your sidetone pitch.
First turn off C W T if it is on. Then, tap S P O T andadjust VFO A until the signal pitch matches thesidetone. Use
M O N to adjust the sidetone
volume level.

In CW and data modes, holding N T C H turns on amanually adjusted notch filter and displays thenotch pitch. Adjust the pitch, using the knob above
the switch, until an interfering carrier is reduced involume. Tap any switch to exit the notch pitch
display. Hold N T C H again to turn it off.

If RIT is turned on, auto-SPOT will change
the RIT offset, not the VFO A frequency.
Auto-SPOT may not be usable if more than one
signal is in the CWT range, or if the signal is very
weak or noisy. Try using a narrower bandwidth in
this case.

In SSB and AM modes, N T C H turns on auto-notch,
which locates and suppresses one or more carriers
automatically.

13

Transmit SettingsV O X selects the keying mode: PTT (push-to-talk)or VOX (voice- or keying-operated transmit). WithPTT selected, the transmitter is enabled by tapping
X M I T or by holding the mic’s PTT button. With
VOX selected, the V O X icon turns on, and transmit
starts by speaking (voice modes) or when keyed(CW mode). Also see D L Y (at left) and
MENU:VOX GN (p. 35).

The TX control group is used to set up the KX3’s
transmitter. The TX LED turns on during transmit.
Caution: Also follow the detailed TX setup
instructions in later sections for each mode.

Transmit and ATU Control
The switches in the group shown below perform
various transmit control functions.

Keyer Speed/Mic Gain and Power Output
In CW mode,
K E Y E R / M I C sets the keyer speed(in WPM). In voice modes, it sets mic gain.
A hold of this knob selects
P W R (power out).
Power in watts is shown on the R F bar graph.
Power output is typically 10 W+ on 160-15 m, and
8 W+ on 12-6 m. The 6-m setting is independent.

M S G and R E C play/record messages (pg. 16, 21).
A T U T U N E starts automatic antenna matching if a

KXAT3 internal ATU is installed (pg. 25). The
ATU MD menu entry must be set to A U T O mode.
Matching takes an average of 4 seconds, initially.
Settings are then recalled instantly on band change,
as well as when you transmit after moving the VFO
a significant distance. The ATU icon will flash
briefly whenever new L-C network settings arerecalled. In CW mode, recall of settings is delayed
until a brief pause in keying (about 0.5 seconds).

If a KXPA100 amp is connected, power can be set
up to 110 W (see KXPA100 owner’s manual).
Maximum available power output varies. If
power is lower than expected, use the special VFO
B displays (pg. 11) to check supply voltage, current
drain, and PA temperature. The selected parameter
will be shown on VFO B during T U N E (SWR isshown on VFO A). A reduced-current TX mode is
automatically used when possible. This is indicatedby a decimal point after the “W” (e.g. 3 . 0 W . ).

With difficult loads, tap A T U T U N E a second
time within 5 seconds to search for a lower SWR.

Other Transmit Settings

A N T controls A N T 1 / 2 selection on the KXAT100
external ATU. A N T does not switch between

Hold
M O N to set the transmit monitor volume(speech in voice modes, sidetone in CW mode).

antenna jacks on the KX3 itself. The BNC jack isalways used on the 160-6 m bands, and the SMA
jack is used only with the KX3-2M/4M module.

C M P sets the amount of speech compression,
which increases average power output, making yourvoice sound louder. Adjust compression using theknob above the switch; to finish, tap C M P again.

X M I T is equivalent to PTT (push-to-talk). Tapping
this switch places the KX3 into transmit mode.
T U N E is used to put out a CW signal at the power
level selected by the P W R control. This is usefulsets the sidetone pitch in CW mode, andthe tone-encode pitch in FM mode (pg. 15). Markor center pitch is shown in some data modes.
PITCH

with external wattmeters and antenna tuners. If the
TUN PWR menu entry is set to a numeric value,rather than N O R , then this value—if lower—
overrides the power control setting.

D L Y sets the VOX (voice-operated transmit) delay
time in voice modes (pg. 15). In CW mode, D L Y
sets the break-in or QSK delay (pg. 16).

14

Voice Modes (SSB, AM, FM)

Transmit Metering in Voice Modes

Basic Voice-Mode Setup
To avoid transmitting a signal during voicemode setup, you can set
P W R to 0.0 watts.

In voice modes, you can switch the transmit bar
graph from S W R / R F to C M P / A L C by tapping
K E Y E R / M I C . This also occurs automatically if
you adjust mic gain or speech compression level.

§Choose a mode: Tap M O D E to select
L S B /U S B , A M , or F M mode. In SSB modes,
A L T alternates between L S B and U S B .

FM Operation

Hold M O N to set the voice monitor level.
High MON settings may result in audio
clipping or distortion. Start with 3 to 5.

To setup for repeater use:§§

To disable FM mode, use MENU:FM MODE.
§

Tap C M P and set it to 0 using the knob above.
Tap it again to exit the CMP display.

§Enable transmit: Tap X M I T or hold in the
mic’s PTT switch. Note: Hand mics like theElecraft MH3 should nearly touch your mouthwhen you are speaking (about 1/8” [3 mm]).

§

Adjust mic gain level: While speaking into themic, adjust
K E Y E R / M I C (mic gain). This
will turn on the transmit C M P and A L C bargraphs. While speaking, adjust mic gain forabout 5 ALC bars (see below). Mic gain for
the Elecraft MH3 is typically 15-25.

§

Speech compression (optional): To use speechcompression, tap C M P and adjust the level
using the knob above the switch. While you’re
speaking, the C M P scale (see above), shows
compression level. High CMP settings may
result in distortion. Start with 1 to 10.

§

Set the power level: Exit transmit mode andadjustP W R to the desired output level.
Do not use MIC gain to set power level. Set
mic gain to a fixed level as described above.

§
§
§

§
§

Hold A L T to select simplex, TX up (+ ), or TX
down (- ). If an offset is in effect, R E V swaps
RX/TX frequencies and offset direction.
Set up the repeater offset (MENU:RPT OFS).
Select FM VFO step size (MENU:VFO CRS).
If PL tone encode is required, hold P I T C H toturn it on (T icon), and rotate the knob above
this switch to select the tone frequency. HoldP I T C H again to turn PL tone encode off.
Selecting 1750 Hz adds EU 0.5-s tone burst;
holding P I T C H during TX extends the tone.
To change the FM deviation level for voice and
PL tones, see MENU:FM DEV.
Squelch: Tap
A F / R F - S Q L , then rotate theknob to select the desired squelch threshold. (Inother modes, the alternate knob function is RF
gain.) Tap the knob again to return to AF gain.

DTMF (dual-tone, multi-frequency): To send
DTMF tones to activate repeater functions: (1) hold
PTT; (2) tap FREQ ENT to enable/disable DTMF
entry; (3) tap 0-9 (use numeric keypad) or special
characters (use MSG = #, ATU TUNE = *, MODE
= A, A/B = B, DATA = C, A>B = D); (4) release
PTT. Note: If transmit is started via the XMIT
switch rather than PTT, and FREQ ENT is thentapped to enter DTMF tones, tap FREQ ENT again
before exiting transmit via the XMIT switch.
Otherwise XMIT will still be assigned to keypad
digit ‘0’, so it can’t be used to end transmit.

Voice Mode VOX Setup

AM OperationV O X selects push-to-talk (PTT) or voice-operated

To disable AM mode, use MENU:AM MODE.

(VOX) transmit (V O X icon on). VOX hold time isset with D L Y (pg. 14).

AM receive on the KX3 uses envelope detection.
You can also listen to AM signals in SSB modes.

MENU:VOX GN (VOX gain) should be set to
trigger at normal speech level, but not in response
to incidental noise. Start with low settings (10-20).
MENU:VOX INH (VOX inhibit, or anti-vox) can
prevent speaker audio from triggering VOX.

In AM transmit, the RF bar graph will indicate
about 1/3 to 1/2 the power set by the power control.
Transmit efficiency is lower in AM mode than SSB
as discussed on pg. 10.
15

CW Mode

CWT, SPOT and Auto-Spot

Basic CW-Mode Setup

When calling a station, you should try to matchyour frequency to theirs. To facilitate this, the KX3
provides both manual and automatic spotting for
CW, FSK-D, and PSK-D signals. See pg. 13.

§§Mode selection: Tap M O D E to select C W(CW normal). In some cases an interfering
received signal can be eliminated by switching
to C W R E V (CW reverse) using A L T . This
doesn’t affect transmit.

CW Text Decode/Display
The KX3 can decode transmitted and received CW
signals, displaying the text on VFO B (pg. 19). Thisis especially useful when you’re learning CW, or if
someone who doesn’t know CW is looking overyour shoulder while you make CW QSOs. It’s also
indispensable for CW-to-DATA operation (pg.18).

Transmitter keying method: The V O X
switch selects either VOX or PTT keying for
CW mode. Most operators use VOX, allowing
the transmitter to be keyed immediately
whenever a hand key or keyer paddle is used.
To manually enable transmit via the X M I T
switch, select PTT.

CW/DATA Message Record/Play§

Set sidetone pitch using P I T C H . The ideal
pitch for most operators falls in the range of
400-600 Hz. The receiver’s passband will becentered at the pitch you select.

There are 6 text message buffers, each holding up to
250 characters. These apply to CW and to DATA
modes FSK D and PSK D.

§

Set sidetone volume using§Adjust the break-in delay: Tap D L Y to set
the break-in or QSK delay (the time before thereceiver recovers after key-up). A setting of 0
provides “full break-in” or “full QSK.” (TheQSK icon will appear.) This allows the receiver
to recover quickly so you can hear anotherstation transmitting between your characters.

Messages can be recorded using the KX3’s
built-in keyer function (using either your keyer
paddle or the KXPD3). An external keyer cannot be
used. Messages can also be created or edited using
the KX3 Utility computer application.

MON.

Message Record: To start recording, hold R E C ,then select a message buffer by tapping any ofswitches 1 through 6 on the numeric keypad. The
remaining buffer space will be displayed as you
send. Tap M S G to terminate record.

CW Receive Filtering
As conditions change, you may need to adjust thefilter passband as described on pg. 12. Also, you’ll
find the audio peaking filter (A P F ) to be very usefulwith weak CW signals.

Message Play: To play, tap M S G , then select amessage buffer ( 1 through 6 ). To cancel, tap X M I Tor hit the keyer paddle or hand key.
Message Erase: Hold R E C , then select a message
buffer ( 1 through 6 ), then hold C L R .

Off-Air Code PracticeSending CW normally produces both a sidetone anda transmitted signal. If PTT-CW is selected (byholding V O X ), hitting the key will generate only asidetone (unless you tap X M I T ). This is useful forcode practice or keyer speed adjustment.

Auto-Repeat: To auto-repeat a message, tap M S G ,but then hold rather than tap a message switch ( 1through 6 ). MENU:MSG RPT sets the message
repeat interval (1 to 255 seconds).
Chaining: Tapping a message switch during
playback chains another message onto the message
being played. Holding a message switch during
playback chains a repeating message.

CW-Mode Menu Settings
Use the menu to set up iambic keying (CW IAMB),
keying weight (CW WGHT), and paddle
normal/reverse or hand key (CW KEY1 for the
KEY jack, and CW KEY2 for the KXPD3). Also
use CW WGHT for CW transmit in SSB mode.

16

Scanning

Advanced Operating Features

Scanning allows the KX3 to tune any portion of aband continuously. Normal scanning mutes thereceiver until a modulated signal is found. “Live”
scanning keeps the receiver unmuted, and is
stopped by the operator. This is useful on very quiet
bands.

Frequency Memories
The KX3 has 100 general-purpose frequency
memories (0 0 -9 9 ), plus four quick memories
on each band, accessed by tapping 1 - 4 on the
numeric keypad. Each memory stores VFO A and B
frequencies, modes, and other settings.

To use scanning:

Quick memories provide an easy way to get tosegments used for each operating mode. For
example, you could use quick-memory 1 as an SSB
starting point, use 2 for CW, 3 for data, etc., oneach band.
To store a general-purpose memory (0 0 -9 9 ):First hold S T O R E , then locate the desired memory
by rotating the VFO A knob. The VFO A
frequencies presently stored in each memory will beshown as you scroll through them. When you reachthe desired memory number, hold S T O R E again tofinish, or tap any other switch to cancel.

§

Set VFO A and VFO B to the desired start/end
frequencies. Also select an operating mode.

§Select a tuning rate for the scan using R A T E(10 Hz or 100 Hz), or K H Z (for fast scanning).

§Store this setup in any frequency memory.

§To start scanning:§

Recall a scanning memory using R C L .

§Hold S C A N to start scanning. To scan with thereceiver live (unmuted), continue to holdS C A N until you see A F O N (about 2 seconds).

To stop scanning: Rotate VFO A or tap any
switch. To restart, hold S C A N .

To recall a general-purpose memory: HoldR C L (recall), then select memory 0 0 -9 9 using
VFO A. Tap any switch to exit.

Channel Hopping
Scanning (or manually tuning) among a group ofmemories is referred to as channel hopping. This ismost useful on channelized bands (e.g., 60, 6, and 2
meters). The memories in the group must all be in
the same band, but can have different modes.

To store a per-band quick memory: HoldS T O R E , then tap the target quick memory ( 1 - 4 ).
To recall a per-band quick memory: HoldR C L , then tap the target quick memory ( 1 - 4 ).

To set up channel hopping:To erase a general-purpose memory: While
scrolling through memories to save or recall, holdC L R . (Not applicable to quick memories.)
To add a text label to a general-purpose
memory: First hold R C L , then select a memory(0 0 -9 9 ) using VFO A. Next, rotate VFO B toselect each text label position in turn as indicated by
the flashing cursor. Use VFO A to change label
characters (A-Z, 0-9, and various symbols). After
editing, hold S T O R E to finish the operation.

§

Set up VFO A for the first target frequency andmode. Store this setup in a general-purpose
memory (0 0 -9 9 ) as described at left.

§

Set up and store the remaining frequencies in
the next successive numbered memories.

§

Add a text label to each memory in the group,
using an asterisk (*) as the first character.

To start manual channel hopping, R C L any one of
the memories in the target group. VFO A will now
hop among the grouped memories as you turn it.

Adding an asterisk (*) at the start of a label
designates a memory that is part of a channelhopping group (described at right).

You can then start scan (or live scan) among thegrouped memories using S C A N . To disable channel
hopping, tap R A T E or change bands.

The K3 Memory program (pg. 28) can be used
to simplify setup and labeling of memories.

17

Data Modes

PSK D Mode (PSK31)

The KX3 supports data operation via a computerand special software. But it can also be used in
RTTY and PSK31 modes without a computer via
the KX3’s built-in FSK D and PSK D modes.

PSK D is the KX3’s built-in implementation of
PSK312, a narrow-band data mode which is reliable
even at very low power levels. 5 watts or less isstrongly recommended to keep distortion low.

5.0 watts or lower is recommended in alldata modes. The KX3 will reduce power, if
necessary, to maintain a safe operating temperature.

To use PSK D, set up the KX3 as described at left
for FSK D, but select the P S K D sub-mode. Before
attempting to transmit in this mode, you should
practice tuning in signals. Try 14070-14073 kHz.
CWT can be used in this mode (see pg. 13).

FSK D Mode (RTTY)
MIC gain, RX/TX EQ, and CMP are notapplicable to FSK D and PSK D modes.

DATA A and AFSK A (Audio Data Modes)
Many audio-generated data transmissions can beheard on the bands, using PSK31, RTTY, Pactor,
Olivia, MFSK, JT65 and other modes. A computer,sound card, and appropriate software are normallyused. D A T A A mode is provided for this purpose.
Unlike SSB modes, DATA A disables compression
and RX/TX EQ. Upper sideband is the default.

FSK D (RTTY1) is the easiest data mode to use:§

Tap D A T A to select data mode.

§

Tap D A T A again and rotate O F S / V F O B toselect the F S K D sub-mode. Tap the switch
again to exit the sub-mode display. A dualpassband (mark/space) filter will appear:§

Hold T E X T to turn on text decode.

For audio-based RTTY, you can also use A F S K A .
Like FSK D, AFSK A provides a dual-passband
RTTY filter and text decode. The VFO is tuned tothe mark frequency. Lower sideband is the default.

§

Hold C W T to turn on the tuning aid (pg. 13).

To use these audio data modes:

You’ll now be able to copy RTTY signals. RTTY
can often be found on 20 meters from 14080-14090
kHz. (If you see only numbers and punctuation, try
tapping D A T A twice to restore “letters” mode.)
To transmit in FSK D mode (CW-to-Data): Pluga keyer paddle into the KEY jack, or attach a
KXPD3 paddle. (See the CW KEY1 and CW
KEY2 menu entries.) When you send CW, the KX3will convert it to RTTY. (You’ll hear the CW
sidetone as well as weak RTTY tones.) You can use
CW message memories in FSK D mode, as well as
KX3 Utility’s Terminal function (pg. 28).

§

Tap D A T A twice; rotate O F S / V F O B toselect the D A T A A or A F S K A . Tap theswitch again to exit the sub-mode display.

§

In A F S K A mode, optionally hold T E X T toturn on text decode, and C W T to turn on the
CW/data tuning aid.

§Connect your computer’s audio output to the
MIC jack. (You can either wire the plug toactivate the PTT line on transmit, or use VOX.)
Connect the KX3’s PHONES jack to yourcomputer’s audio input. High-quality shieldedcables should be used. You may need an
attenuator if the drive levels are too high.

§

Refer to your data communications software
manual to determine how to set up the KX3’s
VFO for accurate frequency display.

§While transmitting audio data, adjust MIC gain
for no more than 4 to 5 bars of ALC indication.

§

RX/TX EQ and CMP are not applicable.

You cannot use a hand key for this function.
The KX3 adds a 4-second “idle time” (giving
you time to decide what to say next) after you stop
sending. To terminate the idle period quickly, send
the character . . - - in CW. This “IM” prosign canalso be inserted at the end of message buffers.

1

FSK stands for frequency-shift keying, used with RTTY
(radioteletype). The KX3 uses a 170 Hz shift. RTTY
signals are encoded using a 5-level code called baudot, at
a baud rate of 45 baud, or about 60 words per minute.

2

PSK stands for phase-shift keying. 31 refers to the baudrate, 31.25 baud. PSK31 signals are encoded using a very
efficient representation called varicode.

18

Text Decode And Display

Split and XIT

The KX3 can decode CW, PSK31 (PSK D) and
RTTY (FSK D). CW speeds from about 8 to 70
WPM can be decoded. Decoded text is displayed on
VFO B. If no signal is tuned in, random characters
may be displayed.

Sometimes you’ll hear a DX station being called bymany other stations. To ensure that he has a clear
transmit channel, the DX station may say “UP” or“DOWN” to indicate that he’s listening above or
below his transmit frequency. For example, in CW
mode he may transmit on 7025 kHz, but listen in
the vicinity of 7027 kHz. In this case he would
periodically say “UP 2” (or just “UP”) as areminder of where to call him. SSB split operation
is similar but may occur over a much wider range.

To set up text decode:§Select the desired mode (CW, FSK D, or
PSK D) using M O D E or D A T A .

§

If a special VFO B display mode is in effect,
cancel it by tapping D I S P .

§You’ll probably want to turn on C W T as atuning aid (pg. 13). This also enables auto-spot,
which can automatically tune-in signals.

§

Hold T E X T . In DATA modes, this willalternate between D E C O N and D E C O F F .
(The T mode icon appears when it is on). In
CW mode, use
O F S / V F O B to select a text
decode mode. T X O N L Y displays only CWcharacters you send using the internal keyer. To
decode text from on-air CW signals, use one of
the R X T H R n settings. Turn C W T on andadjust the threshold so that the CWT bar graphsegment flashes in time with the incoming CW.
Use higher R X T H R n settings for stronger
signals as well as faster CW speeds.

§

Use a filter bandwidth of 0 . 3 0 kHz or less.

§

For further details on data modes, see pg. 18.

To use split, first tap A B twice to set VFO B to
the same mode, frequency, and filter settings as
VFO A. Then tune VFO B up about 2 kHz. Finally,
hold S P L I T (the S P L I T icon will turn on). The T X
icon’s arrow will now point at VFO B, since VFO
B is now controlling your transmit frequency.
Before you transmit using split, you may need tofine-tune your VFO B frequency. Setting it 2 kHz
above VFO A is a good start, but many otherstations may be trying to call at exactly this same
location. The DX operator will be aware of this andwill tune up and down from this nominal frequency
when searching for callers. He’ll probably tune up
in small steps as he “picks off” each station.
This is where the R E V switch comes in: it reverses
the A and B VFOs so that you’re temporarily
receiving on your transmit frequency. During thistime, tune VFO A around a bit to see if you canidentify who is presently working the DX station,then position yourself just above this frequency.

Programmable Function Switches

R E V remains in effect as long as you hold it down.

Two often-used menu entries can be assigned toprogrammable function switches P F 1 and P F 2 .

As soon as you’ve released it, the VFOs will beswapped back, and you’ll once again be listening to
the DX station. With any luck your nexttransmission will occur right where he’s listening.

To set up a programmable function switch:§ Hold M E N U and rotate VFO B to find the target
menu entry.
§ Hold P F 1 or P F 2 to assign it to this menu
entry. You’ll see P F 1 S E T or P F 2 S E T .
§ Exit the menu.
If a parameter has only two values, accessing it witha P F 1 or P F 2 will change the value and exit menu.

Dual watch with split: With dual watch enabled,
you don’t need to use R E V , since you can listen toboth your receive and transmit frequencies (pg. 20).
XIT as an alternative to split: If you’re trying topreserve VFO B as a holding register tuned
someplace else in the band, you may want to use
XIT rather than split in the above situation. In thisexample, you’d turn on X I T and rotate the offset
control to about +2.00 kHz. You’ll then betransmitting 2 kHz above VFO A. To do theequivalent of R E V , you can briefly turn R I T on as
well. Turn off RIT to listen to the DX station.

Macros can also be assigned to P F 1 and P F 2 .
Macros are sequences of control commands that
perform operations such as entering SPLIT modeand moving VFO B up. Refer to the K3 and KX3Programmer’s Reference or KX3utility.
19

Audio Effects

Receive Audio Equalization (RX EQ)

If you have stereo headphones or stereo external
speakers, you can take advantage of the KX3’s DSP
audio effects (AFX). These create an illusion ofgreater acoustic “space,” resulting in a lessfatiguing receiver sound and in some cases better
copy of weak signals.

The KX3 provides 8 bands of receive audio
equalization via the RX EQ menu entry. RX EQ
can compensate for physical acoustics (of the room,
headphones, internal speaker, external speaker),
tailoring the audio to your personal preference.
Two receive EQ setups are provided: one for CW
mode, and the other for all voice modes. RX EQ
does not apply to DATA modes.

MENU:AFX MD is used to select the desired AFX
setting. Available selections include O F F , D E L A Y(simulated stereo), and P I T C H (which “maps”
signals from left to right according to pitch).

In the RX EQ menu entry, the VFO A display
shows 8 individual vertical bar graphs. The example
below shows various amounts of EQ for each band.

Dual Watch
Dual watch allows you to listen to both VFO A andVFO B frequencies at the same time, as if you had
two receivers.

USB
A
VOX
AGC-S

The use of stereo headphones or external
speakers is required with dual watch. You’ll hear
VFO A’s signal in the left ear, and VFO B’s in theright.

A wider roofing filter than normal will beselected automatically, if required, based on thefrequency span between VFO A and B.

§Dual watch overrides the normal audio effects
mode (AFX MD).

§

Headphones or external speakers must be used.

TX
B

The center frequencies of the 8 audio EQ bands are50, 100, 200, 400, 800, 1600, 2400, and 3200 Hz.
To select a band to change, tap 1 - 8 on the keypad.
For example, tapping 1 selects the 50-Hz band.
Next, rotate VFO A to specify boost or cut (+/- 16dB). The illustration above shows the 800 Hz EQ
band (0 . 8 0 kHz) being set to + 1 dB of boost.
You can hold C L R to reset all of the RX EQ bands
to 0 dB (no cut or boost).

Transmit Audio Equalization (TX EQ)
Most microphones, including the Elecraft
MH3, will provide good audio quality with little
or no TX EQ. High settings can cause distortion.

Dual Watch Limitations:

§

RIT

FL2

To turn on dual watch: Set MENU:DUAL RX to
A U T O . This turns on the S U B (“sub receiver”)
icon. If you turn dual watch on/off frequently, you
may wish to assign it to P F 1 or P F 2 (see pg. 19).

The distance between VFOs is limited to 15
kHz. If you exceed this with DUAL RX set to
A U T O , the S U B flashes slowly as a reminder.

XFIL

NB

Dual watch has various uses. For example, you
might be waiting for one station at VFO B’s
frequency to complete a QSO, while using VFO A
to look for other stations. You can tap A / B toalternate between the two. Dual watch is also ideal
for working DX stations who are listening at someoffset from their transmit frequency. You can listen
to the DX station on VFO B, then use VFO A tolisten for a clear spot in which to transmit.

§

ANT 2
ATU
PRE

If required, transmit audio equalization cancompensate for microphone and voice variations.
MENU:TX EQ works exactly the same as RX EQ,
and can be used during transmit. Two transmit EQ
setups are provided: one for SSB, the other for
wideband voice modes (ESSB, AM, FM). TX EQ is
not applicable to CW or DATA modes.
While adjusting TX EQ, monitor your voice using
headphones (useM O N to set the level), or listen
to your transmitted signal on another receiver. If
you hear distortion, reduce all TX EQ bands. You
may also have excessive mic gain or compression.
20

SSB/CW VFO Offset

Transverter BandsThe KX3 can automatically offset the VFO
frequency when you switch from SSB to CW mode,so other stations will hear the correct CW pitch. See
MENU:CW WGHT for details.

Nine user-definable bands are provided for use withtransverters. These can be used with the Elecraft
KX3-2M/4M internal 2-m/4-m module, Elecraft
XV-Series, or other transverters.

Digital Voice Recorder (DVR)

The KX3 does not have a low-leveltransverter output; transverters are driven fromthe main antenna jack. This requires the use oftransverters that have a common receive/transmit
antenna jack and associated T/R switching. Consult
the transverter manual for drive power limitations
and switching requirements.

You can record two voice messages of up to 15
seconds each, such as your call sign or a CQ, andplay them back one time or with auto-repeat.
Use the transmit voice monitor to hear DVR
playback. HoldM O N , then set the level while
speaking into the mic. 5 is a good starting point.

The ACC2 jack provides a keyline output for
keying transverters. The ACC2 jack also provides a
GPIO pin that can be used to select among multiple
transverters based on the band selected at the KX3.
This is further explained below.

DVR Record: Hold R E C , then tap 1 or 2 on the
numeric keypad. The current message will beerased (4 seconds). When prompted, tap X M I T andstart speaking into the mic immediately (no need topush PTT). Tap X M I T again to terminate record.
MIC gain cannot be adjusted during DVR message
play. The gain setting at time of recording is used.

Transverter Band Setup
Transverter bands are set up using the XV menu
entries, as follows:

DVR Play: Tap M S G , then tap 1 or 2 . To cancel,
tap X M I T or hit the keyer paddle or hand key. To
auto-repeat a message, tap M S G , but then holdrather than tap 1 or 2 . MENU:MSG RPT sets
the repeat interval (1 to 255 seconds).

Transmit Noise Gate
The noise gate function mutes mic audio below aselected audio threshold. This is useful in vehicles
and when operating in noisy outdoor environments.
See MENU:TX GATE for details.

§

If a KX3-2M/4M module is installed, set
MENU:2M/4M to N O R or S L E E P n n .

§Locate the XVn ON menu entry. Tap 1 – 9 tospecify which transverter band to configure. Set
the parameter to Y E S to enable band n .

§XVn RF sets the operating frequency (MHz).

§

XVn IF specifies the I.F. band. Use 5 0 MHz
for the KX3-2M option, 2 1 for the KX3-4M.

§

XVn PWR sets maximum power output inwatts for each transverter band. Maximum is
3 . 0 watts for the KX3-2M/4M option.

§

XVn OFS can compensate for frequency offset
in the transverter’s oscillator. (An offset is not
required for the KX3-2M/4M, since its
oscillator signal is derived from the KX3’s
main synthesizer. If there is a frequency error,
calibrate synthesizer using REF CAL.)§XVn ADR should be set to I N T T R N 0 for use
with the KX3-2M/4M module. XVn ADR canalso be used to specify an optional Elecraft XVseries transverter selection address; addresses
T R N 1 -T R N 7 are recognized for this purpose.
To select XV-series transverters using thismethod, set MENU:ACC2 IO to T R N C T R L ,and connect the ACC2 jack’s GPIO pin to thetransverter’s auxBus line.

Transmit Inhibit and External PTT
The GPIO pin of the ACC2 connector can be
configured as a transmit inhibit or PTT input by
setting MENU:ACC2 IO to the desired setting.

Cross-Mode Operation; CW-in-SSB
Cross-mode operation is possible in some cases. For
example, you could set up VFO A for SSB receive,and VFO B for CW transmit, then enter S P L I T .
You can also send CW when SSB mode isselected for VFO A just by hitting the key. The SSB
station will hear the signal at your sidetone pitch.
See MENU:CW WGHT for details (pg. 35).

21

Special VFO B Displays§

The KX3 can continuously display time of day or
one of several operational parameters on the VFO B
display. To access these displays, tap D I S P , thenrotate theO F S / V F O B control.
The available special displays are listed below.
§24-hour time obtained from the real-time-clockon the KXBC3 option module. If a KXBC3 is
not installed, the time since last power-on will
be displayed. Set the time using MENU:TIME.
You can also set an alarm time anytime in thenext 24 hours using MENU:ALARM. This may
be useful as a reminder of a contest or operatingschedule. The alarm will turn the KX3 on if it
occurs when power is off.

§Power supply voltage. This and the next fourparameters stay visible even in transmit mode,so you can check key-down conditions.

§Internal battery voltage. An asterisk (*) is
added to this display during battery charging.
See BAT CHG menu entry.

§§Extended Single Sideband (ESSB)
An increase in SSB voice bandwidth may improvefidelity and reduce listening fatigue. However, thisalso increases signal bandwidth, and is not
appropriate for use when bands are crowded.

Supply current. Typical receive-mode current
is 0.15-0.25 amps (150-250 mA). It will behigher with the backlight, preamp, or isolation
amp on, or when using the KX3-2M/4M.
Transmit current is typically 1 to 3 A, varying
with band, supply voltage, and load SWR.

ESSB receive
The KX3’s normal SSB receive bandwidth is about
2.8 kHz. This can be widened by using the P B T
control. In voice modes, by default function I is
low-cut and function II is high cut. Tap the control
to select function I or II, and rotate it to adjust the
passband. (Also see PBT SSB.)

Power amplifier (PA) temperature. The
KX3’s internal PA temperature is shown as
PA.I nnC (I = Internal). If a 2-/4-m module(KX3-2M/4M) is in use, its PA temperature isshown, as PA.x nnC (where x=2 or 4). If a
KXPA100 is connected via the remote-control
cable, PA MODE is ON, and PWR is 10 W or
higher, the KXPA100’s PA temperature isshown, as PA.X nnC (X = eXternal). PA
temperature will rise gradually as you transmit.

§Synthesizer (OSC) temperature. A few
degrees of OSC temperature rise is normal
during transmit. Also see MENU:REF CAL.

§

Audio Signal level (AFV). Shows the KX3’saudio output level, prior to the AF gain control(the AF gain control has no effect on thisreading). The reading will vary with preamp
and attenuator settings as well as the RF gain
control. AFV is normally used in conjunction
with the dBV function (at right).

Relative audio signal (dBV). This display canbe used to measure receiver sensitivity or
gain/loss of various stages, or compare two
signals. To use it, first select AFV (described atleft) and allow the voltage reading to stabilize.
(This may not be possible with modulated or
rapidly changing signals.) Once the signal
appears stable, select dBV. You should now seea reading of around 0 dBV (see Glossary)
relative to the last AFV reading. If you change
the setting of the preamp or attenuator, you
should see this reading change. However, it
may not change as much as you expect unless
you turn AGC off using the AGC menu entry.
(Be sure to turn AF gain down before
turning AGC off, as the signal may become
very loud.) Measurement of receive sensitivity(MDS) requires a calibrated 1-µV signal sourcesuch as an Elecraft XG3. These sources include
instructions for measuring MDS.

ESSB transmit is set up as follows:22§

Locate the TX ESSB menu entry. Tap 1 to turn
ESSB on, then use VFO A to select the desiredtransmit bandwidth. The + icon will turn on in
the mode area of the LCD.

§ESSB, AM, and FM have separate TX EQ from
regular SSB, allowing you to optimize thetransmit passband for these wider-bandwidthmodes. See the TX EQ menu entry for details.

§You may wish to assign the TX ESSB menu
entry to a programmable function switch if
you’ll be turning it on/off frequently.

Internal Batteries
The KX3’s internal battery pack can be used with eight 1.2-1.6 volt AA cells of any type. The pack typicallyprovides 4-6 hours of casual operation, ideal for field use or as backup during power outages. An internal NiMH
charger is also available (KXBC3, pg. 24).

Opening the Enclosure
To open the enclosure for battery installation, unplug the KXPD3 paddle, then follow the steps below.
1

Loosen all four thumb screws. Then slowly pull the halves apart only about 1/4” (6 mm).

2

Fold open starting at the back.

3

Continue opening. Do not disconnect the flex cable.

When closing the enclosure, be sure not to pinch the battery wires (red and black). If the flex cable
becomes loose at either end, press the connectors back into their sockets.

Recommended Battery Types
Lithium non-rechargeable batteries (e.g., EnergizerL91) are expensive, but their flat discharge curveand 3 amp-hour rating provides maximum operatingtime. In receive, the pack voltage will be about 12
V. In transmit, it will drop to 9-10 V due to thecells’ high internal series resistance. This voltage issufficient for operation at up to 5.0 watts.

Alkaline batteries can be used if there’s no otheralternative, but they have several disadvantages.
They should always be used with power output set
to 3.0 W or less to minimize transmit current drain.
They have a steep discharge curve, so the pack will
drop from 12 V to 8 V in about half the time of
Lithium or NiMH cells.

NiMH (nickel-metal hydride) batteries have a flat
discharge curve, like lithium cells, but a lower packvoltage (typically 10 V receive, 8.5-9 V transmit).
Power output of up to 5.0 W is possible, though 3.0
W is recommended to extend battery life. The
advantage of NiMH cells is that they can berecharged hundreds of times, either externally (in as
little as 1 to 2 hours), or internally (typically 8-12
hours, using the KXBC3 option module).

Alkaline batteries are prone to leakage, andmust be removed after use. Damage caused bybattery leakage is not covered by the warranty.

23

To maximize Battery Life:
§
§
§
§
§
§

VFO Friction Adjustment

Set power to 3.0 W or less when possible.
This uses a high-efficiency transmit mode.
Turn off the backlight (BKLIGHT) and theisolation amp (RX ISO) when not needed.
Use headphones.
Use SLEEP in FM mode (2M/4M).
Use the auto-off timer (AUTO OFF).
Use BAT MIN to set up an appropriate
BAT LOW warning level for your battery type.
Note: Regardless of the BAT LOW warninglevel, the KX3 will turn itself off if the power
supply or battery goes below 7.5 volts.

The spin rate of the VFO A knob can be adjusted bymoving the knob in or out slightly. The rubber
finger grip on the VFO A knob covers the knob’s
set screw, so it must be removed first.
In the following procedure, use only yourfingernails; a tool may scratch the knob.
Using your fingernails at the point identified below,
pull the finger grip forward slightly. Rotate theknob and repeat until the grip can be pulled off.

KXBC3 Internal NiMH Charger
Charge only NiMH cells with the KXBC3.
The KXBC3 module provides a convenient way tokeep internal NiMH batteries charged. You canoperate while batteries are charging.
To ensure safe charging of all NiMH cell types, theKXBC3 uses a “C/10” charge rate (about 200-250
mA, or 1/10th of typical cell capacity in mA-hours).
A 13.8 volt minimum, 500 mA or higher power
supply is required to complete a full charge.
To enable the KXBC3 after installation: Set the
BAT CHG menu entry from N O T I N S T to C H GO F F . Exit the menu. Turn power off and back on.

Use the supplied 5/64" (2 mm) Allen wrench toloosen the set screw.

To start charging: Set BAT CHG to the desired
charge time. If batteries are fully depleted, use 8-16
hours. Exit the menu.

Between the knob and front panel is a felt washer
which, when compressed, reduces the spin rate.
Move the knob in or out in small increments until
the desired rate is obtained. (Re-tighten the set
screw each time so you can spin the knob.) Thenand replace the finger grip.

To cancel charging: Set BAT CHG to O F F . If the
KX3 is turned off during charging, it “hibernates,”
showing remaining battery charge time on thedisplay. The KX3 will turn itself off when charging
is complete.

Real-Time Clock
The KXBC3’s real-time clock (RTC), powered by
the battery pack, shows 24-hour time. Use the
TIME menu entry to set the clock, tapping 1/2/3 toselect HH/MM/SS. Use ALARM to set the alarmtime. To see time displayed on VFO B, tap D I S P .
Preserving clock registers during battery
swap: The current time will be preserved during abattery swap if you connect an external supply or if
you complete the swap within about two minutes. If
the time is lost, use MENU:TIME to reset it.
24

Options and Accessories

Firmware Upgrades

This section describes all available KX3 options
and accessories. Option modules are easily userinstallable, in any order, without soldering.

New features and improvements are available to all
KX3 owners via firmware upgrades. Upgrades may
also be required when you install option modules.

MH3 Hand mic: The MH3 was designed
specifically for the KX3. It includes a high-quality
mic element, rugged right-angle plug, PTT switch,
and VFO UP/DN function buttons.

Please visit the Elecraft KX3 software page(www.elecraft.com/KX3/KX3_software.htm) toobtain our free firmware download application,
KX3 Utility. This program runs on PCs, Macs, andLinux platforms. In addition to firmware
downloading, KX3 Utility provides automated TX
gain calibration, a custom sign-on banner,configuration save/restore, CW/DATA message
editing, and a CW/DATA terminal function.

KXPD3 Keyer paddle: The KXPD3 is anadjustable precision paddle that attaches directly tothe front of the KX3. It can be easily removed forstorage or transport. The paddles are designed forboth left- and right-handed use, and can beelectrically reversed or used as a hand-key.

Some applications or peripheral devices may
interfere with KX3 downloads; check the Help
information in KX3 Utility if you have difficulty.

KXBC3 Internal NiMH battery charger andreal-time clock: If you install NiMH cells in the
KX3’s internal battery pack, you can charge themusing the KXBC3 module (see Internal Batteries,
pg. 23). The KXBC3 also includes a real-time clockwith an alarm function. The time can be displayedin the KX3’s VFO B area by tapping D I S P . The
alarm can be used to turn the KX3 on at a specified
time, or to remind the operator of an on-air event.

Checking your Firmware Revision
Use the FW REVS menu entry to determine yourfirmware revision. The serial number of yourtransceiver, if needed, can be obtained using the
SER NUM menu entry.

KX3 Firmware Self-Test

KXFL3 Dual-bandwidth roofing filter module:
A roofing filter is a narrow-band analog filter that
better rejects strong signals that could cause
receiver blocking (desense) or intermodulation
distortion. When the KXFL3 is installed, the KX3
automatically selects the appropriate roofing filter
as the bandwidth is adjusted (pg. 12).

If the KX3 detects an error in its firmware (anincorrect checksum of all bytes in the program), it
will flash the TX LED and show M C U L D on the
LCD.
If this occurs, connect the KX3 to your computer,then run KX3 Utility, which will reload thefirmware. While firmware is loading, the Delta-F
LED (∆ f ) will flash. When the download iscomplete, the KX3 should reset and run normally.

KXAT3 Wide-range internal automatic antenna
tuner (ATU): With a KXAT3 installed, you can
use single-band or random-length antennas on
multiple bands. Using an ATU can improvetransmit power transfer as well as receive
sensitivity. (See pg. 6 for antenna suggestions.)

Forcing a Firmware Download
If you accidentally load an old or incompatible
firmware version and find the KX3 unresponsive,
do the following: (1) Unplug the KX3 from thepower supply. If internal batteries are installed, also
remove one battery. (2) Plug a power supply in (orreinstall the removed battery). (3) hold the KX3’s
B A N D - and A T U T U N E together for about 10
seconds, after which you’ll see the TX LED flash(you’ll also see M C U L D on the LCD). (4)Connect the KX3 to a computer and run KX3
Utility, which will load new firmware.

KX3-2M (2-m) or KX3-4M (4-m) module:
Provides all-mode, low-power operation on 2 or 4
meters. Great for emergency field communciations,coordination, etc.
KXPA100 100-W amplifier: The KXPA100 is arugged 100-W, 160-6 m amp that can be used withany QRP transceiver. An optional internal 100-W
ATU is available for the amp (KXAT100).
PX3 Panadapter: A full-color, fast, precision
spectrum display fully integrated with the KX3.
25

SDR Applicationsgroups for your program that can help if you havedifficulty understanding its installation or operation.

The KX3 provides a special receiver output jack,
RX I/Q, for use with the Elecraft PX3 Panadapter.
The RX I/Q output can also be used for softwaredefined radio (SDR) applications3 running on acomputer or other device.

A PC program suitable for most purposes is“HDSDR”. It is available as of this writing at
http://www.hdsdr.de
Follow the directions provided by the HDSDR
program for setup and operation. Another popular
SDR program is “NaP3”.

The primary benefit of such applications is that, likethe PX3, they can provide a real-time display of aband of frequencies above and below the signal towhich the KX3 is tuned. You can use this display toquickly find signals of interest, examine modulationand noise characteristics, etc. (This capability canalso be found in dedicated instruments calledpanadapters or spectrum analyzers.)

Tips for setting up SDR Programs with the KX3:
§

Since the KX3’s RX I/Q signal is analog, it must be
converted to a digital signal by means of a twochannel (stereo) analog-to-digital converter (ADC).
Most PCs have this in the form of a built-in stereo
sound-card. It is important that the input to the
PC be in stereo. Most “mic” inputs are mono, andcannot be used. Most “line inputs” are stereo, andcan be used.

When you first run the SDR program, thefrequency displayed may be incorrect, but the
spectrum display will still be accurate in termsof offsets. Setting the center frequency display
to 1.000 or 10.000 MHz, for example, will
make it easy to see how many kHz above or
below the current KX3 frequency anothersignal is.

§

If your PC lacks a suitable input, there are thirdparty soundcards available for USB, PCI, PCIe,
Firewire and other expansion buses.

Initially connect only the IQ signal cablebetween the KX3 and the PC soundcard. Leave
the USB/serial cable for radio control
disconnected until you have the spectrum
display working properly.

§

There are many SDR applications available as
freeware on various platforms (PC, Mac, iPad, etc.).
The quality of the spectrum display they provide
depends heavily on the quality of the soundcard’s
ADC inputs. An excellent reference on potentiallysuitable sound cards may be found on the web bysearching for “LP-PAN sound card tests”.

Select the correct soundcard input for the
program. If your PC has an internal soundcard
but you are using an add-on card, you must
configure the program to use the correct
soundcard.

§

A cable with a 2.5 mm (3/32”) plug on one end anda plug that matches your sound card input on theother end (typically 3.5 mm [1/8”] stereo) is
required.

Set the correct sampling rate. Use of 48 kHz
sampling will result in a display of almost 48
kHz: 24 kHz above and 24 kHz below thefrequency to which the KX3 is tuned. 96 kHz
sampling will yield approximately +/- 48 kHzof spectrum, and 192 kHz sampling will yield adisplay of about +/- 96 kHz.

§

Once you have a cable and soundcard, you’ll needto download suitable software and load it on yourPC. Follow the directions supplied by the program,
usually in the form of a help file. There may be user

Enable the RX IQ output from the KX3 bysetting MENU: RX I/Q to O N . (This increases
the KX3’s receive-mode current drain by about
10-15 mA.)§

The RX I/Q outputs from a receiver are not“flat” over an infinite frequency range; thesignal-conversion process results in some slope(decrease in gain) as you move farther from thecenter frequency. In the case of the KX3, thesignal will be reduced by about 2.5 dB at +/- 24
kHz, 4 dB at +/- 48 kHz, and 7 dB at +/- 96
kHz. The spectrum amplitude on the display,

3

The RX I/Q jack’s analog signal is in I and Q format. I
and Q refer to the two parts of a phase-quadrature signal,
which simply means the two signals are 90 degrees apartin phase. The PX3, as well as PC software applications,
can use this information to mathematically reconstruct
the signals for display and demodulation purposes.

26

including the apparent noise floor of thereceiver, will “roll off” by these amounts.
§

If you have an accurate signal level source(such as an Elecraft XG-series signal source ora signal generator), you can calibrate the signal
amplitude following directions provided by the
SDR program.

§

After you are comfortable with setting up andusing the spectrum display, you can connect theUSB/serial cable between the PC and the KX3.

§

Typically, some spectral noise will appear in
the display in the form of “spikes” ormodulation sidebands. These can arise fromseveral sources, including nearby power
supplies, ground noise, or the computer and its
peripherals. You can often use isolationtransformers, improve grounding, and shieldedcables to reduce the amplitude of these signals.
Note: Try setting up without isolationtransformers, initially. They can sometimes
add signal pickup that makes the spectrum
display much noisier.

§

Some low-level spikes may appear in the
spectral display that originate at the KX3.
These are usually low enough in amplitude to
be masked by band noise when a suitableantenna is connected.

§

The HDSDR program can also display theactual frequency range in use if it is set up tocommunicate with the KX3. To do this, set up
the program to use KX3, K3, or Kenwood
protocol using the procedure and support files
described on the HDSDR website. Connect the
KX3’s ACC1 jack to a USB or RS232 port on
the computer (see pg. 5). After configuration,
the program should then correctly display theactual signal frequencies as you tune the KX3.
You may also be able to tune the KX3 from theprogram, depending on the program’s features.

27

Remote Control of the KX3function cannot be used for power-on control. Use
only the MIC PTT line.)

Computer Control and Logging

To turn the KX3 off, the controller must send the
KX3 a “PS0;” command via the ACC1 jack (RS232
or USB, depending on the cable used). If thecontroller also turns off the KX3’s power supply, it
should first allow 100 ms for the KX3 to shut down.

With appropriate software, any computer with an
RS232 or USB port can be used to control the KX3.
Required connections are covered on pg. 5.
Third-party logging and contesting software isavailable for various computers and operating
systems. Select KX3 as the target radio whenavailable. If not, select K3 or K2.

Automatic Antenna Control
Some antenna control units (e.g., those used with
SteppIR™ antennas) can track the KX3’s band andfrequency by watching for “IF;” (rig information)
packets from the transceiver. Some computer
logging/contesting applications set up the KX3 to
output these messages periodically, allowing theantenna control unit to “eavesdrop.”

For a list of compatible software applications,
including configuration requirements, please visit
http://www.elecraft.com/k2_remote.htm

Using the KX3 as a Remote Front PanelIf you’re not using such software, or if you’re notusing a computer at all, you can still set up the KX3
to output “IF;” packets periodically to an antenna
controller. To do this, set MENU:AUTOINF to
A N T C T R L . The packets are sent once per second
while the VFO frequency is being changed, as wellas on any band change.

You can use the KX3 as a front panel for a remotely
located KX3 or K3. (At present this feature isexperimental, providing limited control
capabilities.) The two transceivers can be tied
together via the internet or wiFi using adapters at
each end that handle data and audio. An alternative
is to tie the transceivers together directly via theserial port (ACC1), using a “null-modem” cable (acable with the tip and ring connections swappedfrom one end to the other).

If you’re using logging/contesting software,check with the manufacturer before setting
AUTOINF to A N T C T R L . Some applications may
not be tolerant of unsolicited “IF;” packets.

To enable the remote-control function at the “local”
KX3, which acts as a front panel only, set
MENU:AUTO INF (auto-info) to R I G C T R L .

CW/DATA Terminal Applications

Remote-Control Commands

The KX3 directly supports CW/PSK31/RTTYASCII text transmit and receive via its ACC1 port
(RS232 or USB). Our KX3 Utility application
includes a Terminal function that lets you use thesemodes with your computer’s keyboard and monitor.
At the KX3, select FSK-D data submode for RTTY,
and PSK-D for PSK31. Then follow the Help
instructions within KX3 Utility.

The KX3 has a rich set of remote-control
commands. These commands use ordinary ASCII
characters, so they can be easily tested using aterminal emulator or the Command Tester screen in
KX3 Utility. For example, the command “FA;”returns the current VFO A frequency. Using thesame command, you can set the frequency, e.g.
“FA00007040000;” sets the VFO to 7.040 MHz.

K3 Memory Program

Many specialized commands are provided inaddition to the core set of commands supported by
the K3 and K2. Please refer to the K3/KX3Programmer’s Reference for further details.

The KX3’s frequency memories (pg. 17) can beeasily viewed and changed using our K3 Memory
PC application. This program shows the contents of
all 100 regular memories and the per-band quickmemories in a spreadsheet format.

Remote Power On/Off
To turn the KX3 on, a remote-control system canplace 8 to 12 volts DC on the mic jack’s PTT line
for 100 ms or longer. (The ACC2 jack’s PTT IN pin

You can also set VFO A directly to a memory fromwithin the K3 Memory program.

28

Configuration

Menu Settings
The menu entries described in this section can beused to tailor KX3 operation to your own needs.
You may also want to review the full list of menu
entries, starting on pg. 35.

You’ll need to set up Option Module Enables (seebelow) anytime you add one or more option
modules. This is done at the factory for factoryinstalled options.
Some Menu Settings (beginning at right) should be
set up before you use the KX3 on the air.

After changing menu settings, use KX3
Utility to save your present configuration. The
configuration can then be restored later if required.

Option Module Enables

Audio Effects

Whenever an option is installed, use the associatedmenu entry to set it up (see Menu Functions, pg.
35). When installing internal options, open the
KX3 enclosure using the procedure on pg. 23.

If you sometimes use stereo headphones or two
external powered speakers, try setting the audio
effects mode (AFX MD) to D E L A Y . (This has noeffect on the internal speaker.) D E L A Y creates asimulated stereo effect that can reduce listening
fatigue. If you encounter a pile-up of CW signals,
try the P I T C H setting, which “maps” signals fromleft to right in the audio space based on their pitch.

§

§

§

§

§
§
§

KXAT3 Antenna Tuner (ATU): Set ATU MD
to A U T O . Exit the menu and turn the KX3 off,
then back on. See pg. 6 for recommended
antennas and pg. 14 for ATU controls.
KXFL3 Roofing Filter Module: Set RX XFIL
to N O R . Exit the menu and turn the KX3 offfor 5 seconds, then back on. You must thenperform the Receive Sideband calibration
procedure (pg. 32).
KXPD3 Keyer Paddle: Set CW KEY2 to
L eF T paddle = D O T (normal) or = D A S H(reverse). If you set it to H A N D , either paddle
can be used as a hand key. Note that the KEY
jack on the left side panel is configured using
the CW KEY1 menu entry. The device plugged
into KEY is independent of the KXPD3.
KXBC3 Internal NiMH Battery Charger:
Set BAT CHG to C H G O F F . Exit the menu
and turn the KX3 off for 5 seconds, then backon. See Internal Batteries (pg. 23) for battery
recommendations and charging instructions.
KX3-2M/4M Module: See 2M/4M and XVnmenu entries and associated manual.
KXPA100 External 100-W amplifier: See
PA MODE menu entry and KXPA100 manual.
PX3 Panadapter: Set RX I/Q to O N . Also see
PX3 manual.

AM and FM Mode Disable
If you don’t plan to use AM and/or FM modes, you
can disable them individually using the AM MODE
and FM MODE menu entries.

Auto Power-Off
The KX3 can turn itself off after a specified period
of inactivity (i.e., no use of the controls). This ismost useful when the unit is running from a small
battery. Use the AUTOOFF menu entry to selectthe time period in minutes. The default is
INFINITE.
If battery charging is in progress, the KX3
won’t turn itself completely off; it will “hibernate”
until charging is complete (pg. 24).

Low-Battery Warning
You can set BAT MIN to warn you when aninternal or external battery is approaching end of
charge. B A T L O W is displayed periodically when
this level is reached. The default voltage (1 0 . 0 V)
is appropriate for many 12-V batteries. For
suggested low-battery warning levels for otherbattery types, see the BAT MIN menu entry.

After changing option enables, use KX3
Utility to save your present configuration. The
configuration can then be restored later if later
required.

The KX3 will turn itself off when the supply
voltage drops below about 7.5 volts, regardless of
the BAT MIN setting.

29Band Map

Setting the Time

If there are some bands you don’t plan to use, you
can remove them from the band-switch rotation
using BND MAP. This can save time whenswitching bands. Within the BND MAP menu
entry, you can switch bands using B A N D + andB A N D - . Set each band to I N or O U T as desired.

MENU:TIME sets the 24-hour real-time-clock(RTC) if a KXBC3 module is installed. If noKXBC3 is installed, the displayed time will start at
0 0 : 0 0 : 0 0 when the KX3 is turned on.
While in the menu entry, tap 1 / 2 / 3 to selectHH/MM/SS (hours/minutes/seconds), respectively.
Then use VFO A to adjust the value. KX3 Utility
can also be used to accurately set the time.

CW Iambic Mode
CW users can specify Iambic mode A or B using
the CW IAMB menu entry. The default is mode A ,which is a little more forgiving for first-time
operators. Mode B may be preferred by operators
who learned to do “squeeze-keying” with anotherkeyer having this or a similar mode. Both modes
provide dot- and dash-memories—enabling fastcode speeds—but with slightly different timing.

Tap D I S P and rotate VFO B to display the presenttime.

VFO Setup
Several menu entries are provided to control VFO
behavior:§

VFO CRS sets up the K H Z tuning increment
for each mode (coarse tuning) on a per-mode
basis.

§

VFO CTS specifies the number of counts perknob turn (VFO A and B): 1 2 8 or 2 5 6 . The
lower setting makes fine-tuning easier,especially for mobile use. The higher setting
allows quicker tuning.

§

VFO OFS, if set to Y E S , allows the OFS/VFO
B knob to do coarse tuning of VFO A. (Thisonly applies if the knob is not being used for
RIT, XIT, or to select VFO B display modes.
See pg. 35.)

Microphone Settings
If you plan to use voice modes, set up MIC BIAS
and MIC BTN to match your microphone (pg. 35).

Preamp Gain (Per-Band)The default (and recommended) preamp gain is 2 0
d B . However, you can select 1 0 d B if 20 dB is toomuch gain on a given band. (Operating with thepreamp turned off may be a better choice in suchcases.) The 10-dB preamp adds about 15 mA toreceive-mode current drain, while the 20-dB
preamp adds only about 5 mA.

TUNE Power Level

A 3 0 d B selection is also available that turns
on both preamps. However, this setting increases
susceptibility to strong signals. It is the default
setting on 6 meters, where the combination of thetwo can improve sensitivity by 1 to 2 dB.

If you’re using an external antenna tuner oramplifier with the KX3, you may need to limit thepower level used during T U N E . The TUN PWR
menu entry can be used to set the desired power
level. For example, with an Elecraft T1 ATU, thebest tuner power level is about 3.0 watts.

Switch press Tones
Switch press tones are enabled by default. Using theSW TONE menu entry, you can turn tones O F F ,O N , or select Morse code control tones at various
speeds (C O D E n n ). The full list of Morse code
control characters, as well as a text-only panel
description for blind operators, can be found on our
KX3 web page.

If you have the KXAT3 internal ATU installed,power is automatically set to 3.0 watts during
antenna tuning. There’s no need to configure
TUN PWR for this purpose.

VOX (Voice Operated Transmit) Setup
If you plan to use VOX in voice modes, you’ll needto set up the VOX GN and VOX INH (anti-VOX)
menu entries.

Switch tones use the CW sidetone volume level,
which can be adjusted in CW mode (pg. 12).

30

aid, with the C W T icon turned on. This enables
the auto-spot function to be used below.

Calibration

Method 2 (manual tuning): This method
requires manually matching the pitch of thereceived signal to the CW sidetone pitch using
S P O T . To prepare for this, you may need toincrease sidetone volume. See pg. 12.

Most calibration steps are performed at thefactory for both kit and assembled KX3s.
There is one exception: If you install a KXFL3
roofing filter after initial purchase, you’ll need toperform the Receive Sideband calibration step
(pg 32).

§

Locate the I/II icons (right end of the filter
passband graphic). If function II is selected, tap
P B T I / I I to select function I (bandwidth).

§Rotate theP B T I / I I control to set the
bandwidth to 0.30 kHz (B W 0 . 3 0 ).

§

Tap P B T I / I I to switch to function II (shift).

§

Rotate theP B T I / I I control until the filter
passband is centered in the filter graphic.

§

Hold M E N U , then rotate
O F S / V F O B tolocate the REF CAL menu entry.

Reference Frequency§Hold K H Z for about 3 seconds to unlock theparameter (shown on VFO A).

Using the calibration procedure below, you canachieve accuracy of better than +/- 1 ppm. This
procedure requires a stable signal generator, or an
on-air signal at a known frequency, such as WWV
at 5, 10, or 15 MHz. The carrier of a commercial
AM broadcast station can also be used.

§

If you see only 7 digits, tap R A T E .

§

In case you decide to restore the factory setting,write down the full 8-digit parameter value:_________________ .

§

Method 1 (automatic tuning, CWT on): Tap
S P O T to auto-spot the signal. The REF CAL
parameter value should automatically move up
or down a small amount. When it finishes
moving, the bar directly beneath the C W T icon
should be turned on as shown below. The
reference will then be closely calibrated.

Viewing tech-mode menu entries: To view themenu entries used during calibration, hold M E N U ,then rotate
O F S / V F O B to locate the TECH
MD menu entry. Use VFO A to change theparameter to O N .
To unlock the parameter for a tech-mode menu
entry: Hold K H Z until you see the lock symbol( ) turn off (about 3 seconds).

If better frequency stability is desired, refer tothe Extended VFO Temperature Compensation
procedure, available on our KX3 web page.
During the procedure, you’ll have a choice of
two methods for adjusting the reference frequency:(1) automatic tuning, or (2) manual tuning.
Method (2) may be slightly more accurate but
requires “zero-beating” of two signals, which some
operators may find difficult to do.
§Select CW mode by tapping M O D E .

§Hold M E N U . Rotate
O F S / V F O B to find
DUAL RX. Set it to O F F , then exit the menu.

§

If you’re using a signal generator, set
to 0.0 watts to avoid damaging it.

§Use direct frequency entry (pg. 10) to set VFO
A to the exact frequency of your signal
generator or on-air signal source. This will also
switch the KX3 to the required band.

CWT
S1 3 5 7 9

SWR

Set AF gain for a comfortable listening level.
You should be able to hear a carrier.

§

Method 1 (automatic tuning): Hold C W T .
The upper half of the S-meter becomes a tuning

RF

50

100

Method 2 (manual tuning, CWT off): Tap
S P O T and manually adjust the REF CAL
parameter using VFO A until the received
signal pitch matches the sidetone pitch. Adjust
for zero-beat.

PWR

§

2 3

31

§

If you have difficulty with this procedure, or if
you’re not sure that it worked correctly, set theparameter value to its original value (recorded
above) using VFO A.

§

If you have adjusted the REF CAL value moreaccurately, write down the new value (8 digits)
here for future reference: ______________ .

§

Exit the menu by holding M E N U .

§Save your configuration using KX3 Utility.

Receive Sideband

Transmit Bias

Receive sideband calibration nulls (rejects) the
opposite-sideband image. This image is a weak
audible side-effect of very strong signals.

This automated procedure sets the transmit bias
current of the 10-watt amplifier stage to ensure low
distortion. No test equipment is required.

This calibration step is done at the factoryfor KX3s shipped with the KXFL3 option attime of purchase, whether factory assembled orkit. It must be performed by the owner only if a
KXFL3 is purchased and installed later. Pleaserefer to the instruction sheet supplied with the
KXFL3 option.

§

Make sure nothing is connected to the KX3’s
BNC antenna jack.

§Hold M E N U , then rotate
O F S / V F O B tolocate the TX BIAS menu entry. Hold K H Z forabout 3 seconds to unlock the two parameters.
Note: These parameters cannot be manually
adjusted.

§

Select CW mode by tapping M O D E .

§Tap X M I T to start CW bias calibration. This
may take 3-10 seconds. If an error message
appears at the end (E R R n n n ), see
Troubleshooting.

§

Select SSB mode (LSB or USB) by tapping
MODE .

§

Tap X M I T to start SSB bias calibration.

§

Exit the menu by holding M E N U .

§Save your configuration using KX3 Utility.

32

Transmit Gain
This procedure compensates for per-band transmit
gain variations at two different power levels, andmust be done on every band. As described below,
the procedure can be done manually, or you can use
the a fully-automated procedure provided by the
KX3 Utility program. A 6-watt (minimum) dummyload is required in either case.
A 12-14 volt external power supply orbattery must be used during this procedure.

Automated Transmit Gain Calibration§

If a computer is available, you can use theautomated transmit gain calibration procedure.
Connect the KX3 to the computer, run KX3
Utility, and select the Calibration tab.

§

Click on Calibrate Transmitter Gain andfollow the on-screen instructions.

§

Save your configuration using KX3 Utility.

Manual Transmit Gain Calibration§Use direct frequency entry (pg. 10) to set the
KX3’s operating frequency to 1.9 MHz (160
meters).

§

If you have the KXAT3 ATU option installed,
put it into bypass mode (MENU:ATU MD).

§

Set the TUN PWR menu entry to NOR.

§Connect a dummy load to the BNC jack.

§

Set

§

Hold T U N E ; wait until VFO B shows 4 . 0 W.

§

Tap X M I T to exit TUNE.

§

Repeat the above procedure on 80-6 meters.
Use approximately the following frequencies:
3.7 MHz (80 m), 5.4 MHz (60 m), 7.1 MHz (40m), 10.1 MHz (30 m), 14.1 MHz (20 m), 18.1
MHz (17 m), 21.2 MHz (15 m), 24.9 MHz (12m), 28.8 MHz (10 m), 52 MHz (6 m).

§

Repeat transmit calibration at 6 . 0 W on all
bands.

§

Save your configuration using KX3 Utility.

PWR

to exactly 4.0 watts (pg. 14).

33

Transmit Carrier

Transmit Sideband

In SSB and some data modes, a transmitter’s
primary signal may be accompanied by a weakunmodulated signal called a carrier about 1 kHz
away. The carrier should be suppressed (or nulled)
to minimize interference to nearby stations. The
TXCRNUL menu entry is used for this purpose.

In SSB and some data modes, a transmitter’s
primary signal may be accompanied by a weak
opposite sideband signal about 2 kHz away. Thissignal should be suppressed (or nulled) to minimize
interference to nearby stations. The TXSBNUL
menu entry is used for this purpose.

This procedure requires a spectrum analyzer
and is normally done only at the factory.
Complete instructions are available on request.

This procedure requires a spectrum analyzer
and is normally done only at the factory.
Complete instructions are available on request.

34

Menu Functions
Hold M E N U to enter the KX3’s menu. Tap or hold this switch to exit. Menu entries that you’d like quick
access to can be assigned to programmable function switches (pg. 19). Note: N O R appears in some parameter
displays. This means “Normal,” i.e. the default or recommended value.

Menu Help Information
Holding M E N U for about 3 seconds while in the menu shows information about the present menu entry on
VFO B. For most entries, the default parameter value is shown in parentheses at the start of the help text. Tap
the switch to terminate the help text display.

Tech-Mode menu entries
The
symbol in the table below indicates a tech mode menu entry. These are typically used for calibration, or
should be changed with caution. Their parameter values are locked by default, as indicated by the lock symbolon the display. To see tech-mode menu entries, set MENU:TECH MD to O N . To change any tech-mode
parameter, you must first unlock it by holding K H Z for about 3 seconds. This turns off the lock symbol.
Entry
2 TONE

DefaultOFF

2M/4M

Not Inst

ACC2 IO

OFF

Description
Enables built-in 2-tone generator for SSB transmit tests. The internal 2-tone
generator only works if LSB or USB mode is selected. After setting 2-tone O N ,exit the menu and tap X M I T .
If a KX3-2M or KX3-4M module is installed, set to N O R or to one of the
S L E E P modes (see below). See XVn menu entries (or KX3-2M/4M installation
manual) for additional setup instructions.
SLEEP Settings: SLEEP .25 (0.25 seconds) through SLEEP 1.0 (1.0 seconds)
specify the sleep time between receive-signal checks when the receiver is in FM
mode, and squelched. With these settings, receive-mode current drain decreases
by up to 50%, extending operating time when using a small battery.
Temperature Sensing: By default, KX3-2M/4M temperature sensing takes placein both RX and TX modes. To turn sensing off in transmit for diagnostic
purposes, tap 1 to change the setting to TX TMP- instead of TX TMP+.
Determines the function of the GPIO signal (ACC2 jack’s “tip” connection):O F F (output, 0 V), O N (output, 3 V), L O = P T T (input; apply 0 V or ground toactivate PTT), H I = P T T (input; apply 3 to 5 V to activate PTT), L O = I n h (input;
0 V inhibits transmit), H I = I n h (input; 3 to 5 V inhibits transmit), T R N C T R L(output; XV-series transverter control using Elecraft auxBus prototcol). If the
GPIO signal is inhibiting transmit, the T X icon will flash as a reminder.

AF LIM

NOR 030

NOTE: External interface circuitry may be required. The GPIO pin is a 3-V
logic input/output with a 500-ohm series current-limiting resistor. It is tolerant of
0-5.5 VDC when used as an input. If a voltage outside this range is to be used,
insert a larger series resistor. (Example: when an RS232 RTS signal is used toactivate PTT, use a 2.2 to 10 K series resistor.) When the GPIO pin is used as an
output, its 3-V logic high may not be sufficient for use with some equipment. In
this case a 3-V to 5-V level translation circuit can be used.
Adjustable AF output limiter for use when AGC is turned off. This can protect
your ears if a large signal appears. Signals or noise above the threshold will soundhighly distorted due to the limiting action, reminding you to back down the AF or
RF gain. Typical settings for those who often turn AGC off are 17 to 23; someexperimentation will be required.
35

AFX MDDelay

AGC MDON

AGC SPDSLOAGC*THR

007

ALARM

OFF

AM MODEON

ATU MD
ATU.X MD

Not Inst

Sets up stereo audio effects (requires stereo headphones or dual external
speakers). Set to OFF for no effects. D E L A Y is quasi-stereo, which provides avery rich audio sound. P I T C H does left/right pitch mapping, which can be very
effective in CW mode.
Some operators prefer to turn AGC off and control gain manually using the RF
gain control; see pg. 12. (When AGC is off, the AGC icons on the LCD change to
A G C - , with the “minus” sign meaning “off”.) If an uncomfortably-strong signal
appears in your headphones or speaker, see AF LIM (AGC-off audio limiter).
This setting is stored per-mode. The default for CW mode is F A S T , and for othermodes, S L O . The setting is indicated by the A G C S and F display icons.
This menu entry provides access to several AGC parameters, each of which starts
with A G C * . For most purposes the defaults will suffice. Tap the 1 through 6
switches to access the following parameters (defaults in parentheses):
1 A G C * T H R (005): Threshold at which AGC action begins. A higher number
moves the threshold up, providing greater audio dynamic range.
2 A G C * A T K (215): Rate of AGC attack. A lower number than the default
provides a softer attack but may also result in overshoot.
3 A G C * H L D (000): Hold time in seconds for voice modes. Prevents AGC
decay for a specified time after attack, reducing AGC interaction with signals.
4 A G C * D C Y (Fast, 140; Slow, 040): Specifies the decay rate for slow or fast
AGC (see AGC SPD menu entry). A larger number means a faster decay.
5 A G C * S L P (015): The higher the slope number, the "flatter" the AGC
response is. With a high setting of slope, signals above the AGC threshold will beheld close in audio amplitude even if they vary in strength at the RF input.
6 A G C * P L S (NOR): Noise pulse rejection. Prevents the AGC (and S-meter)from charging up on one-shot noise events. Set it to OFF to disable this feature.
Set alarm/Auto-Power-On time. Tap 1 to turn alarm on/off; tap 2 / 3 to set
H H .M M . If a KXBC3 option module is installed and an internal battery is
installed, time will be maintained when power to the transceiver is turned off.
Otherwise the time registers will reset to 0 0 : 0 0 : 0 0 on power-up.
At the alarm time, the KX3 will emit three short beeps. If power had been turnedoff, AF output will then be restored to the last-used level.
Set to O F F if AM operation is not planned. You can still copy AM signals using
SSB modes even if AM is turned off.
KXAT3 (or KXAT100) ATU mode. If a KXPA100 is connected via the remotecontrol cable, and PA MODE is ON, the ATU MD menu entry changes to ATU.X
MD (X = eXternal). In this case the menu entry directly controls the mode of the
KXPA100’s 100-W ATU (KXAT100), not the KX3’s low-power ATU (KXAT3).
The parameter is normally set to B Y P or A U T O . Modes L 1 - L 8 , C 1 - C 8 , and C t
are used to test the KXAT3’s relays and L-network (not applicable to the
KXAT100). Tapping C L R clears stored LC data for the present band (applies towhichever ATU is in use, KXAT3 or KXAT100).
AM Broadcast Band Optimization: When a KXAT3 is installed, it normallyprovides additional filtering to reject “image” responses when listening to signals
in the AM broadcast band (0.5-1.6 MHz). However, this may reduce recevier
sensitivity below 1.3 MHz. If signals in the lower portion of the broadcast band
are too weak, try tapping ‘1’ in this menu entry to select BCB=160 mode rather
than BCB=NOR (default). BCB=160 causes the KXAT3 to use the normal 160meter LC settings when tuned anywhere in the broadcast band.
36

AUTO INF

NOR

AUTO OFFINFINITE

BAT CHG

Not Inst

BAT MIN

10.0

BKLIGHTON

BND MAP{band} In

COR LVLNOR 0.1

CW IAMBA

CW KEY1

TIP=DOTCW KEY2

LFT=DOTCW WGHT

1.25

If set to A N T C T R L , the KX3 will send band data (“automatic info”) to its
ACC1 jack for use with devices such as SteppIR™ antennas. The data is sent on
every band change, and once per second if the VFO is being moved. See pg. 28.
If set to R I G C T R L , the KX3 will function as a front panel for remote control ofa second KX3 (or a K3) via an internet or wiFi connection. See pg. 28.
Sets auto-power-off time in minutes (the timer is retriggered when any control isused, and during transmit). If set to I N F I N I T E , power is never turned off. A
setting of 5 or 1 0 minutes is recommended when running from batteries.
If the KXBC3 option is installed (NiMH charger and real-time clock), set to
C H G O F F normally. To charge batteries, used one of the timed-charge settings.
See KXBC3 manual for detailed information on battery charging. See pg. 24 forbattery installation instructions.
Low-battery warning threshold. The default (1 0 . 0 volts) is sufficient for use withsome 12 V batteries such as gel cells. For eight internal NiMH batteries, a settingof 8 . 5 V is recommended. For internal alkaline or nonrechargeable lithium
batteries, use 9 . 0 V. If the internal battery or external supply/battery voltage
drops below this level, the operator will be alerted with B A T L O W messages
every few minutes. The KX3 will turn itself off if the supply voltage drops below
7.0 V. For tips on extending battery life, see pg. 24.
LCD backlight on/off. The display is transflective, so it can be seen in sunlightwith the backlight turned off. Turning it off will extend battery life.
Allows you to remove one or more bands from the B A N D rotation. Use B A N D
up/down to select bands, then set them to I n or O u t using VFO A. (Works withtransverter bands, too.) You can still get to mapped-out bands using memory
recall, direct frequency entry, or computer-control commands.
Sets the carrier-operated-relay (COR) threshold. The COR is used to detect, andprotect the KX3’s receiver from, a transmitter being used nearby. 0 . 1 watts is thedefault and recommended level. See Troubleshooting for other suggestions.
Iambic keying mode (A or B ). The default is mode A , which is a little more
forgiving for first-time operators. Mode B may be preferred by operators wholearned to do “squeeze-keying” with another keyer having this or a similar mode.
Both modes provide dot- and dash-memories—enabling fast code speeds—butwith slightly different “element-insert” timing.
Specifies whether the left keyer paddle (tip contact on the KEY jack) is D O T or
D A S H . A third selection, H A N D , allows either tip or ring to function as a hand
key, or as an input for an external keying device (keyer, computer, etc.).
Specifies whether the left lever of the optional KXPD3 keyer paddle is D O T or
D A S H . A third selection, H A N D , allows either lever to function as a hand key,or as an input for an external keying device (keyer, computer, etc.).
Adjusts element/space timing ratio (weight) for the internal keyer. Also:
Tap 1 to select S S B - C W (default) or S S B + C W (allows CW in SSB modes).
With SSB +CW, tapping KEYER/MIC knob in SSB mode alternates between
keyer speed and mic gain. CW TX in SSB mode is not available if SPLIT is on.
Tap 4 to select V O X N O R (default) or A U T O O F F . The A U T O O F F setting
turns CW VOX off on power-up, avoiding accidental keying by attached PCs, etc.
Tap 5 to select automatic VFO offset on SSB/CW mode change (V F O O F S ) or
no offset (V F O N O R , default). Automatic offset is often used on 6 meters, wheremixed-mode QSOs are necessary during fading. Note: Pitch matching will be
more accurate if USB is paired with CW REV, and LSB with CW normal.
37

DUAL RXOFF

FM DEV

5.0

FM MODE
FW REVSON
N/A

LCD TST
LED BRT

OFF
4

MACRO nFunction

MIC BIASONMIC BTNPTTUP.DN

MSG RPT

6

PA MODEOFF

Set to A U T O to enable Dual Watch (pg. 20). The S U B icon will turn on. If the
VFOs are not within the required range, the S U B icon will flash slowly. Note:
Dual watch only applies when using stereo headphones or dual external speakers.
FM voice deviation in kHz. Tap 1 to change the function to PL DEV (PL tone
deviation; default 0.36 kHz). To turn on PL tones, use P I T C H (pg. 15).
If set to O F F , FM will be removed from the mode selections.
Rotate VFO A to see firmware revision: µ C (microcontroller), d S P , and P A(KXPA100). Tap 1 to see RF PC board revision.
Rotate VFO A to turn on all LCD segments for test purposes.
In the case where the LCD backlight is turned OFF, this menu entry adjusts
brightness of the discrete LEDs (TX, delta-F, OFS, and VFO B LED). Does not
set brightness of the LCD backlight itself (for that adjustment, use BKLIGHT).
Used to assign macros (sequence of remote-control commands) to either of the
KX3’s programmable function switches (PF1 and PF2). For example, a single
macro can do the equivalent of “SPLIT, up 2 kHz, turn on Dual Watch”, etc.
Macros must first be created using KX3 Utility and sent to the KX3. Refer to
KX3 Utility’s Help information for instructions and examples.
Set to O N for the Elecraft MH3. You may need to try both MIC BIAS settings to
see which works best. Monitor signal with another receiver when testing audio.
If your mic has both a PTT switch and UP/DN buttons, set the parameter to
PTT UP.DN. This applies to the Elecraft MH3. If the mic has PTT but no UP/DN
buttons, use P T T . Otherwise, use O F F . This applies to most headset-mics,
including the Heil models available from Elecraft. Third-party mics may not havea KX3-compatible PTT (push-to-talk) switch. You can still key the transmitter
either by tapping the X M I T switch or by using VOX (pg. 15).
Message repeat interval in seconds (0 to 2 5 5 ). To repeat a message, hold M 1 –M 4 rather than tap. A 6 - 10 sec. interval is about right for casual CQing. Shorter
intervals may be needed during contests, and longer for periodic CW beacons.
Sets the operating mode for Elecraft KXPA100 amplifier and its internal ATU.
Set to O N only if the KX3 is connected to the KXPA100 via the KX3 control
cable, which plugs into the ACC1 and ACC2 jacks at the KX3. This allows the
KX3 to control the amplifier’s output power, ATU tuning, antenna switch, etc. as
described in the KXPA100 owner’s manual. ATU MD becomes ATU.X MD.
Set to O F F otherwise. This allows the KX3 to be used with the KXPA100
without the custom control cable, but an amp keying connection is still required
from ACC2 on the KX3 to KEY IN on the amplifier.
If PA MODE is set to P out CAL, a KXPA100 is connected via the remotecontrol cable, and PWR is set to CAL 75W, going into TUNE mode will calibrate
the KX3’s drive level for 75 W output at the KXPA100, on the present band. Thisoverrides the KXPA100’s factory aligned, per-band drive-power calibration, andshould not be necessary under normal circumstances. Also see MENU:TX GAIN.
PA ALC: Tap 1 to turn PA ALC on/off (the default is on, or P A A L C + ). When
PA ALC is on, and KXPA100 power is set to 70 W or less (at the KX3), theoperator can use the KX3’s TUNE switch function to more accurately set theamplifier’s output level. Refer to the KXPA100 manual for details.
Transient Fault Display: Transient KX3-to-KXPA100 communication errors
are normally corrected without alerting the operator. For diagnostic purposes,
they can be displayed as “FAULT nnn” where nnn is a 3-digit number originatingfrom the KXPA100. To enable this, tap 6 until you see X F A U L T + .
38

PBT SSB

Lo-Hi Cut

Sets up the PBT I and II receive filter functions for SSB mode. L o C u t and H i
C u t (functions I and II, respectively) are the defaults for SSB. If PBT SSB is set
to N O R , then SSB mode will have the same PBT funcitons as CW and DATA
modes (WIDTH and SHIFT).
Roofing Filter Configuration for SSB Mode: Roofing filter FL2 (3 kHz) can beinserted when the upper edge of the receive passband reaches either 2.4 kHz(default value) or 2.9 kHz. When the passband edge is higher than this, FL1 isused (wide filter). (If no KXFL1 is installed, FL1 is always used.)If you frequently encounter QRM in SSB modes, use the 2.9 kHz selection; thiswill insert FL2 when the normalized passband width is used (NORM switch). If
QRM is less of an issue or you frequently use ESSB, use the 2.4 kHz selection(original value); this will insert FL1 at the NORM setting. The PBT knob canoverride either selection (see below). To select the desired FL2 insertion point:
Tap ‘1’ to select either 2.4 or 2.9 kHz using the criteria above.

PREAMP

20 dB

REF CAL

114.nnn.nn

Note on SSB demodulation methods used for FL1 vs. FL2: When FL1 is inselected (wide filter), the KX3 uses conventional SSB demodulation, providing
the best overall audio fidelity. When FL2 is selected (3 kHz filter), the KX3 uses
“Weaver” SSB demodulation, which introduces a narrow 1.5 kHz notch into thereceive passband as part of the DSP algorithm. This notch typically has no impact
on speech intelligibility, but it can sound slightly different to an operator who ismost concerned about fidelity.
Sets preamp gain to 1 0 , 2 0 , or 3 0 d B on a per-band basis. (30 dB is typicallyused only on 6 meters, where it improves sensitivity by 1-2 dB. This setting
should only be used if necessary, since it increases susceptibility to overload.)
There are actually two preamps: the 20 dB low noise amp (LNA) and the 10 dB
setting of the isolation amp (see RX ISO, below). Use the 20-dB preamp whenpossible, since it has a better noise figure and lower current drain. If you select 10
or 30 dB, the isolation amp is turned on, adding about 15 mA to current drain.
Used to calibrate the KX3’s synthesizer; normally this is done at the factory. VFO
A is used to set the reference frequency (typically 114.2-114.4 MHz). Refer to pg.
31 for calibration details.
Note: If the menu name is REF*CAL, then an extended VFO temperaturecompensation procedure has been performed. This may be helpful when JT65,
WSPR, or other modes are used with the KX3, especially on the higher bands.
Instructions can be found on our website.
Tapping A T T N disables synthesizer temperature compensation (“TC OFF”),
changing REF CAL to REF#CAL, and OSC xxC (temp. display) to OSC#xxC.

RPT OFS

600

RS232

4800 bRX EQ-------(+0 dB,
each
band)

RX I/Q

OFF

Sets the transmit offset (in kHz) for repeater operation, from 0 to 5 0 0 0 kHz.
Stored per-band and per-memory. Use A L T to select +/- offset or simplex.
RS232 (or USB) communications rate in bits per second (bps). During firmware
download (via the KX3FW PC program), the baud rate is set automatically to
38400 baud, but it is then restored to the value selected in this menu entry.
Receiver audio graphic equalizer. VFO A is used as an 8-band bar graph, showing
boost or cut ( - 1 6 dB to + 1 6 dB in 1 dB increments) for each AF band. The 8
bands are 0.05, 0.1, 0.2, 0.4, 0.8, 1.6, 2.4 and 3.2 kHz. Tap 1 - 8 to select an AF
band. VFO A selects boost/cut. Hold C L R to reset all bands to +0 dB.
CW and voice mode RX EQ are separate. Not applicable to DATA modes.
Set to O N to use the KX3’s RX I/Q jack with the Elecraft PX3 Panadapter, orwith SDR (software-defined radio) applications (pg. 26).
39

RX ISOOFF

RX NR p

CW:
B=5
D=240
M=250
Voice:
B=20
D=240
M=250

RXSBNUL

GAIN nnn

RX SHFTNORRX XFIL

Not Inst

SER NUM
SMTR MD

N/ANOR

SW TESTOFFSW TONEON

Set to O N if you’re using the KX3 nearby other receivers operating on the same
band, and a strong carrier from the KX3 is heard when its VFO is tuned to thesame frequency as the other receiver’s. The isolation amplifier is between theantenna jack and the mixer, preventing leakage from the KX3’s local oscillator.
Note 1: Most operators will not need to use this menu entry, which provides finecontrol of receive noise-reduction parameters. The N R switch function provides
convenient control of the most important parameter (wet/dry mix); see pg. 13.
Note 2: Even if you do set up NR parameters using this menu entry, you’ll stillneed to use the N R switch to turn NR on/off.
Note 3: NR is not available in DATA modes or when AGC is off (see AGC MD).
Note 4: Holding C L R while in this menu entry will restore all NR defaults.
The letter <p> in the menu name will be either B (beta), D (decay), or M (wet/drymix). Tap 1 , 2 , or 3 , respectively, to select these parameters. Beta and Decay
affect the depth of noise reduction and the time required for the DSP’s algorithm
to settle. The defaults are recommended, and are stored separately for CW andvoice modes. Mix controls how much of the signal is processed (wet) vs. howmuch is unprocessed (dry). This parameter should be used to set the overall
receive noise reduction effect. The N R switch function directly controls the mix.
Used to null (reject) the opposite-sideband image signal of each of the KX3’s
analog filter paths. If the menu name is RXSBNL*, then an extended per-band
calibration procedure has been completed. Normally this is done at the factory.
This procedure requires a 160-6 meter signal source (such as an Elecraft XG3);
instructions are available on our website.
Also see Receive Sideband calibration, pg. 32.
Normally the KX3’s receive I.F. is 0.0 kHz (N O R setting). If a nearby transmitter(or automobile DC power noise) causes audible artifacts in the KX3’s receiver,the I.F. can be shifted up to 8 . 0 kHz to reduce or eliminate such artifacts. With
this setting, dual watch and roofing filters cannot be used. This setting is perband, and should only be used on affected bands.
Set to N O R if a KXFL3 filter module is installed. The RXSBNUL calibration
procedure must be performed when this module is installed (pg. 32).
Your KX3’s serial number, e.g. 0 5 0 0 0 . Cannot be changed.
S-meter mode: When set to N O R , turning the preamp or attenuator on/off willaffect the S-meter reading. If set to A B S , the S-meter reading will stay fairly
constant with different preamp and attenuator settings.
To turn on switch test, rotate VFO A until the parameter becomes S C N A D C .
Then hold any switch to see its scan row and column ADC reading. You can also
rotate any of the four potentiometers to see their associated ADC readings(main/sub AF gain and main/sub RF gain). If the SUB RF pot is mapped to
main/sub squelch, you must switch to FM mode to see its readings.
If set to O N , switch presses generate audible tones. If set to C O D E n n , Morse
code characters are generated on any control activation at n n words per minute.
(The full list of Morse code control characters, as well as a text-only panel
description for blind operators, can be found on our KX3 web page.)
Switch tone volume is the same as CW sidetone volume, adjusted withMON.
Pitch of switch tones and Morse characters: In general, a low-to-high tone pair(or high-pitched Morse) is generated when a switch function is turned on, andhigh-to-low (or low-pitched Morse) when it is turned off.
Some switches do not generate tones because they might interfere with received
or transmitted audio.
40

TECH MDOFF

Set to O N to view Tech Mode menu entries (those marked with

TIME

N/A

TUN PWR

NOR

Real-time-clock view/set. Tap 1 / 2 / 3 to set HH / MM / SS. To see the time andother displays during normal operation, tap D I S P (see pg. 11). Time is only
maintained if a KXBC3 option module and an internal battery are installed.
If set to N O R , T U N E power level follows the POWER knob. Otherwise, theparameter sets a fixed power level (0-10 W) for T U N E , overriding the present
POWER knob setting.

TX BIASTXCRNUL

ppp qqq
1 nnnnTX DLYHF NORTRN NOR

TX EQ+0 dB,
each band

TX ESSB

OFF 3.0

TX GAIN

ALC nnin this list).

Note: TUN PWR does not pertain to A T U T U N E , which uses 2 or 3 W(KXAT3) or 5 W (KXAT100).
Transmit bias constants. See Transmit Bias, pg. 32.
Used at the factory to null the transmit carrier on each band. See Transmit
Carrier, pg. 34.
Varies the delay in milliseconds between key-down and RF output. This is usefulwith external power amplifiers having slow T/R relays (use NOR with the
KXPA100 if there is no following higher-power amplifier). There are two TX
DLY settings: one for HF-6 m (HF) and the other for transverter bands (TRN).
NOR (5 ms) is recommended in most cases. A delay of up to 20 ms can be set,
but use the smallest delay possible since longer delays can add some timing
variation in CW mode at higher code speeds.
Transmit audio graphic equalizer (voice modes only). Functions the same as RX
EQ, above. TX EQ can be adjusted during transmit. SSB TX EQ is separate fromTX EQ for other voice modes. Not applicable to CW or DATA modes.
Do not use high settings of TX EQ without carefully monitoring yoursignal. Most microphones, including the Elecraft MH3, will provide goodaudio quality with little or no TX EQ. High settings can cause distortion.
Extended SSB transmit bandwidth (3 . 0 to 4 . 0 kHz) or O F F . Tap 1 to turn on/off
and rotate VFO A to select the bandwidth. (Also see pg. 22.)
Shows whether transmit ALC (automatic level control) is enabled, along with thetransmit gain constant for the present band and power setting (nn). Two gain
constants are used: one for PWR settings of 5.0 watts or less, and the other for
PWR settings of 5.1 watts or higher. The gain constants are calibrated whenever
the T U N E function is activated at exactly 4 . 0 or 6 . 0 W. See Transmit Gaincalibration procedure, pg. 33.
If a KXPA100 is connected via the remote-control cable, PA MODE is ON, andPWR is 10 W or higher, the TX GAIN parameter shows the KX3 drive level for
75 W output at the KXPA100. If the drive value is preceded by a the letter ‘A’, it
was obtained from the KXPA100 (factory calibration value). If the drive value ispreceded by the letter ‘t’, it was obtained by doing P out CAL at 75 W at theKX3 itself (see MENU:PA MODE). Holding CLR will erase the KX3’s CAL
value on the present band, restoring the ‘A’ value (from the KXPA100).
Transmit ALC can be turned off for 2-tone testing or other purposes by tapping
D L Y while in this menu entry. (This is NOT necessary for any operational
purpose. In DATA modes, ALC is already optimized for low distortion.) When
ALC is turned off, a (-) sign is added to the parameter, e.g. - A L C n n . Also, anasterisk is added to the P W R control value when it is being adjusted (e.g. 5 . 0
W * ). In this case, the displayed power level will not change; the control functions
as a fine power adjustment, and its effect should be observed with an external
instrument.
41

TX GATE

OFF 0

The TX noise gate can be used to suppress transmitted audio below a certain
level, e.g. that of an amplifier fan. Tap 1 within the TX GATE menu entry to turnthe noise gate on/off. Use VFO A to set the desired threshold. Since there’s novisual indication that transmit audio is below the threshold, you should adjust it
using the transmit voice monitor (MON), ideally while using headphones. Set thethreshold high enough to cut off transmit audio due to local noise, but not so highthat it causes your voice to drop out too frequently.

TXSBNULVFO CRSGAIN nnn
Per-mode

VFO CTS256

VFO NROFF

VFO OFSON

VOX GN030

VOX INH000

WATTMTR

0.84

XVn ONNO

XVn RF144

XVn IF28

XVn PWR

H 0.1

XVn OFS

0.00

Set at factory to null transmit opposite sideband. See Transmit Sideband, pg. 34.
Coarse tuning rate (hold K H Z , tune VFO A or B). Applies to the RIT/XIT tuning
knob if MENU:VFO OFS is set to O N , and both R I T and X I T are turned off.
VFO counts per turn. Use 1 2 8 for easier fine-tuning of VFO; use 2 5 6 for fastertuning. Note: The K H Z tuning rate always uses 128 counts per turn.
VFO tuning noise reduction. If VFO tuning noise is heard on a given band, set to
O N . The setting is stored per-band. Typically it would be used only on 6 metersor other high-frequency bands. (Also see RX SHFT.)
If O N , the RIT/XIT offset control can be used to tune VFO A in large steps when
R I T / X I T are off and the OFS function of the OFS/VFO B knob is selected. Step
sizes vary by mode (see VFO CRS), and are the same as the K H Z tuning rates.
Adjusts sensitivity of VOX to match your mic and voice. Set to trigger at normal
speech level, but not in response to noise. Start with low settings (10-20).
Adjusts immunity of the VOX circuit to false triggering by speaker audio. (Alsoknown as anti-vox.) A setting of about 30 is a good starting point. If receive audio
from a speaker trips the vox, increase the setting.
Wattmeter calibration parameter. The default setting is recommended. If an
external, known-accurate wattmeter reads lower than the KX3’s wattmeter,
decrease the parameter value (and vice-versa). Note: The ATU (KXAT3), evenwhen bypassed, may cause a small amount of loss (typically less than 0.5 dB).
Internal wattmeter accuracy may vary by up to 1 dB, varying with band.
Tap 1 – 9 to select the applicable transverter band (1 - 9 ). Set parameter to Y E S
to turn the transverter band on.
Lower edge for transverter band <n> (1 -9 ); 0 -2 4 9 9 9 MHz. (Tap 1 – 9 to selectapplicable transverter band.) Use 1 4 4 for the KX3-2M internal 2-m module, and
7 0 for the KX3-4M 4-meter module.
Specify KX3 band to use as the I.F. for transverter band <n> (1 -9 ) . (Tap 1 – 9 toselect the transverter band.) I.F. selections include 7 , 1 4 , 2 1 , 2 8 , and 5 0 MHz.
Use 5 0 MHz for the KX3-2M 2-m module, and 21 for the 4-meter module.
Sets upper limit on power level in watts for XVTR band <n>. Tap 1 – 9 to selectband.
The KX3 does not have a low-level transverter port, so external transverters musthave their own T/R switching and be able to handle the specified power level.
Offset (– 9 . 9 9 to +9 . 9 9 kHz) for transverter band n (1 -9 ). (Tap 1 – 9 to selecttransverter band.) Compensates for oscillator/multiplier chain errors in externaltransverters. Not applicable to the internal KX3-2M/4M module, which derives its
signal from the KX3’s synthesizer.

42

XVn ADR

TRNn

Assigns optional band-decode addresses to transverter bands. Addresses T R N 1 -7
can be used to select Elecraft XV-series transverters if the ACC2 IO menu entry
is set to T R N C T R L and the transverters are connected to the ACC2 jack(tip=auxBus, ring=key out). TRN0 is used with the KX3-2M/4M module(internal). Tap 1 – 9 to select the transverter band; rotate VFO A to select theaddress.
To configure an Elecraft KX3-2M 2-meter module as XVTR band 1, set XV1
ON to Y E S , XV1 RF to 1 4 4 MHz, XV1 IF to 5 0 MHz, and XV1 ADR to I N T
T R N 0 . For the KX3-4M module, use 70 MHz for RF and 21 MHz for the IF. The
XV1 OFS menu entriy is not applicable in either case. Set and XV1 PWR to thedesired maximum power output on 2 or 4 meters, in watts (max 3.0; reduce powerif 2- or 4-meter antenna SWR is poor or when using internal batteries).

43

Troubleshooting
The most common symptoms and their causes are listed below, in three categories (general, transmit, andreceive). Most problems are related to control settings. If the problem persists, please contact Elecraft support(see pg. 55) or post a question on our email reflector.

General§

MCU LD shown on LCD and TX LED flashing: Do a forced firmware load (pg. 25).

§***** shown on LCD permanently: This indicates that the KX3 did not power-down correctly.
Disconnect power for a few seconds, then try a forced firmware load (pg. 25).

§

Display backlight turns on, but then turns off on release of switches: Disconnect all external equipmentfrom the KX3. Verify power supply or battery voltage is between 9 and 15 V. Open enclosure and makesure cable between the two main PC boards is fully plugged in at both ends.

§

E R R n n n (error) message appears in the VFO B area: Refer to Error Messages (pg. 47). If a large

number of error messages are seen at power-on, re-seat the flex cable between the RF and control boards.
§

P A F L T (power amplifier fault) message appears in the VFO B area: See KXPA100 owner’s manual.

§

B A T L O W is flashed periodically: Check the battery voltage (tap D I S P and rotate VFO B until the supply

voltage display appears). If the batteries are at their normal voltage, you may have MENU:BAT MIN set to
the wrong low-battery warning level. See this menu entry for recommendations.
§Can’t turn power on: Check the power cable. If running from internal batteries, make sure they’re
installed, seated properly, oriented in the right direction, and charged.

§Can’t turn power off: If the display remains on, or the unit is otherwise unresponsive, disconnect thepower supply. (If internal batteries are in use, also remove one battery.) Allow 5-10 seconds, then reconnect
power and try turning the unit on.

§General problem with transmit and/or receive: Many problems can be caused by low power supply
voltage or by a noisy or intermittent supply. Check your power supply’s on/off switch, voltage, fuses (ifapplicable), and DC cabling. The KX3 provides both voltage and current monitoring (pg. 11). Also see
Transmit and Receive troubleshooting sections, below.

§

General problem with firmware behavior: (1) Check all menu settings (see menu listings in the previous
section). Hold M E N U for about 3 seconds to see help information about each menu entry. (2) Try loading
the latest microcontroller and DSP firmware. Review the release notes for changes that may be related toyour symptoms. (3) If the above suggestions don’t help, try reinitializing the firmware (pg. 46). Be sure tosave your configuration first, using KX3 Utility.

§Bands missing from B A N D switch rotation: See MENU:BND MAP.

§

N / A message (Not Applicable): The function you’re trying to use does not apply in the present context.

§Mode icon flashes: This is a reminder that you’re about to set the KX3 up for cross-mode SPLIT operation(VFOs in different modes). Tap any key to clear. To view and change VFO B’s mode, tap A / B .

§

VFO A frequency doesn’t change: You may have the VFO locked. Tap R A T E to unlock.

§

VFO A frequency changes by itself: (1) If using a mic other than the MH3, set MIC BTN to OFF. (2) If
necessary, adjust the VFO A knob height so that the knob contacts the felt pad (see pg. 24).

Transmit§

B N D E N D : Attempt to transmit out of the allowed ham band.

44

§

TX LED on all the time: This could indicate that PTT is being held on by external equipment. Try
disconnecting everything connected to the left side panel except the power supply. VOX gain (VOX GN
menu entry) may be set too high. Also check the ACC2 IO menu setting.

§

H I C U R or H I S W R warning: Check supply voltage. If voltage is low and/or a low-impedance antennaload is present, current can go up for a given requested power level. Reduce power if necessary. (The KX3
may do this automatically. If this doesn’t reduce the current or reflected power to safe levels, the KX3 will
drop out of transmit mode.)§

H I T E M P warning: PA heat sink temperature has exceeded the safe operating limit. Use D I S P to check

power supply voltage, current drain, and PA temperature. Allow heat sink to cool. Reduce power ifnecessary. (The KX3 may automatically reduce power, drop out of transmit mode, or turn itself off.)§

KX3 enclosure is hot to the touch on the back edge: During hand-held or lap-top operation at high poweror high duty cycle, the enclosure may feel uncomfortably warm. Reduce power or use shorter transmissions.
Note: At 3.0 watts or lower, the KX3 uses a high-efficiency (lower-current) transmit mode, reducing therate of heating and extending battery life.

§

An asterisk (*) appears in the P W R setting display (e.g. 5 . 0 W * ): Transmit ALC has been turned off. To
turn it back on, go to MENU:TX GAIN , unlock the parameter by holding K H Z for 3 seconds, then tap
D L Y . This will turn off the (- ) sign in front of A L C .

§Can’t transmit in any mode: The ACC2 IO menu entry may be set to H I = I N H (transmit inhibit when the
GPIO pin is pulled high or is floating high).

§Can’t transmit in CW mode: (1) Make sure the key or keyer paddle is plugged into the correct jack.
(2) To transmit immediately upon hitting the key, you must have VOX-CW enabled (hold V O X ) . If VOX isoff (PTT-CW), you must tap X M I T before sending; otherwise only a sidetone is generated . (3) You may bein S P L I T mode, with VFO B set for a voice or data mode. Tap A / B to check VFO B’s mode.

§Can’t use the mic in voice modes: You may be in S P L I T mode, with VFO B set for CW or data mode
rather than a voice mode. Tap A / B to check VFO B’s mode.

§Low power output: (1) Make sure transmit is not inhibited (see ACC2 IO menu entry); (2) try redoing theautomated Transmit Gain calibration procedure (pg. 33). Note: Max power varies by band (pg. 54).

§

Inadequate transmit carrier or opposite-sideband suppression: The voice- and audio-data carrier andopposite sideband will typically be down 60 dB or more at 10 watts output. If either is significantly higher
than this level, the Transmit Carrier or Transmit Sideband calibration steps (pg. 34 and 34) must be
performed. These procedures require a spectrum analyzer and are normally done only at the factory.

Receive§

H I R F I warning, preamp turns off, or R X icon turns on: The KX3 protects itself from high received

signal levels. First, the preamp is turned off, if it was on. (You may be able to avoid this by using the 10-dB
preamp rather than the 20-dB preamp on the current band. See MENU:PREAMP.) The second step takenby the KX3, if necessary, is to turn on a 15-dB attenuator stage in the I.F. section, ahead of the receiver’s Ato-D converter. The receive overload icon (R X ), near the A N T icon, will turn on. Once signals return to asafe level for 5 seconds, this attenuator will be turned back off. Also see COR (next item).
§Carrier-operated relay activated (a relay is heard, and the R X icon turns on): The carrier-operatedrelay (COR) may be activated due to the signal from a nearby transmitter. This is usually due to close
proximity between your antenna and the other station’s antenna. The COR is actually the relay for thepresent low-pass filter. When the relay opens, signals will drop by 40 to 60 dB, protecting the KX3. The
relay will close again shortly after the signal drops. If the COR is being repeatedly activated, try moving theantennas farther apart. You can also increase the COR threshold, at your discretion; see MENU:COR LVL.

§H I C U R warning: Usually indicates speaker volume is too high; gain is reduced by the KX3 in this case.

§No received signal: Check (1) antenna connectors; (2) squelch (FM mode); (3) RF gain too low (set RFgain control fully clockwise, to – 0 d B ); (4) bandwidth too narrow (PBT I/II control); (5) MENU:REF CAL
parameter not adjusted properly; (6) KXFL3 menu entry set to N O R but module not installed.
45§

Received signal level too low: (1) check headphone and speaker plugs and cables; (2) make sure that
MENU:RX EQ has not been set for large cuts; (3) verify that MENU:REF CAL is properly adjusted; (4)make sure RF gain is set to maximum; (5) preamp set to 10 dB rather than 20 dB (MENU:PREAMP).

§

Spurious signals (“birdies”): All receivers exhibit some birdies. Most will be inaudible with an antennaconnected. In the KX3, there may be significant birdies or harmonics of birdies at the following frequencies
due to internal signal sources: 16000 and 18432 +/- 5 kHz (MCU and DSP clock frequencies), 300-900 kHz(DC-DC converter oscillators, CMOS RF switches). In the unlikely event that a birdie interferes with
operation, try CW reverse, manual notch, or (in voice modes) auto-notch.

§

Opposite-sideband images heard: Opposite-sideband suppression is 50-60 dB. If images appear too highin amplitude, carefully redo the Receive Sideband calibration procedure (pg. 32). If sideband image
rejection is poor only for FL2 and/or FL3, but not FL1, the KXFL3 roofing filter module may be at fault.

§

VFO tuning noise heard: Set VFO NR (VFO noise reduction) to O N on the affected band, and/or set
RX SHFT to 8.0. Even with these settings there may be very weak tuning noise heard, especially when noantenna is connected. Dual RX and roofing filters are disabled on any band where RX SHFT is set to 8.0.

§Mobile installation noise: If the 12-V DC accessory jack in a vehicle causes interference to the KX3’s
receiver, try setting RX SHFT to 8.0 on the affected band(s).

§Low-level signals are heard that don’t change as the VFO is rotated: In a zero-I.F. receiver, it’s possible
for extremely strong signals to create audible artifacts, due to AM detection at the mixer, that are notaffected by tuning the VFO. If this occurs, first try turning off the preamp (and/or turning on the attenuator).
Another alternative is to set the RX SHFT menu entry to 8 . 0 (kHz) on the affected band(s), although withthis setting, dual watch cannot be used. If the source of such signals is a nearby transmitter (such as at Field
Day), you may be able to reorient or move one of the antennas, or use an external band-pass filter.

§

KX3 VFO signal is heard in a nearby receiver: If a nearby receiver is picking up the KX3’s VFO signal,
turn on the isolation amp (RX ISO menu entry). Note: This increases current drain by about 15 mA if theisolation amp was not already being used as a 10-dB preamp. Turn RX ISO off when not needed.

§Internal speaker distortion at high volume: The KX3’s small internal speaker is not intended for use inhigh-noise environments, such as in a vehicle or outdoors in high winds. If audible artifacts occur at higher
volume levels, switch to headphones or an external speaker. (Stereo also allows the use of audio effects.) If
you hear distortion products even at low levels, verify that the speaker plug is inserted exactly as shown in
Fig. 17 of the KX3 assembly manual. Also try loading new firmware (rev 1.41 or later improves audio).

§AM broadcast signals in the 300-700 kHz range appear to be off-frequency: Broadcast signals thatappear not to tune in at even multiples of 1 kHz may be images of signals higher up in the band. You caneliminate most images by installing the KXAT3 ATU option, which includes broadcast band filtering.

Parameter Initialization (EEINIT)
It is possible, though rare, for EEPROM parameters to become altered in such a way as to prevent the firmware
from running correctly. If you suspect this, you can reinitialize parameters to defaults, then restore a previouslysaved configuration (or re-do configuration steps manually; no test equipment is required). To initialize:§

IMPORTANT: Run the KX3 Utility program and use the Save Configuration function to save yourpresent firmware configuration. (Otherwise, you’ll need to re-do calibration steps after EEINIT.)§

Turn the KX3 off (using the KX3’s on/off switch combination, not your power supply).

§While holding in the P B T I / I I knob with your right hand (which is also labeled NORM below the knob),turn power on with your left hand by holding B A N D - and A T U T U N E together for about 2 seconds, thenrelease. Release the P B T I / I I knob after another few more seconds. You should see E E I N I T on the LCD.

§When E E I N I T completes, you may see E R R n n n due to initialization. Tap D I S P to clear messages.

§

Restore all parameters using the Restore Configuration function of the KX3 Utility program. Then turnpower off and on again. See if the original problem has been resolved. If not, contact Elecraft.
46

Error Messages (ERR nnn)
Error messages may be displayed on VFO B at power-up or during normal operation. In many cases error
messages are due to a problem with a single option module or incorrect firmware configuration.
Some error conditions suggest doing an EEINIT if other remedies fail. DO NOT DO AN EEINIT
unless: (1) you have tried re-seating the internal flex cable between the control panel and RF board, thenpowering the unit back on, and (2) you have previously saved your KX3’s configuration file using KX3 Utility.
Elecraft can provide a copy of your factory configuration file if needed.
If you see an error message on VFO B (E R R n n n ): Write down the error message, as well as any associatederror data shown on the VFO A display (e.g. d = 0 0 5 ). Then tap any switch to clear the error code. Multiple
errors may occur; in this case, write down each of the messages and VFO A data, if any, before you clear them.
See Error Message table below for details on specific E R R messages and associated data values, if any.
Error Msg
ERR 2MERR ACPERR ATC,ERR ATD,ERR ATIERR ATR

ERR BC3ERR DS1ERR DS2ERR DSE,
DSX

Problem
KX3-2M/4M module error.
d = n n n identifies specificproblem. 001, 002 = not found.
PTT activation via the ACC2
jack detected at power-up

KXAT3 module not accessible:
ATC = I/O expander C
ATD = I/O expander D
ATI = I/O address mismatch
KXAT3 relay failure (on VFO
A, d = n n n identifies the failing
relay, e.g. 0 0 1 for relay K1)
KXBC3 module error (battery
charger/real-time-clock).
d = n n n is the specific error
code (report to Elecraft).
No DSP SPI command echo
DSP SPI echo not inverted
DSP command timeout.
d = n n n is the last DSP
command sent.

ERR DSP

DSP, CODEC, or ADC powerup self-test failed

ERR EE1

On-chip EEPROM read/write
test failed
External EEPROM read/write
test failed

ERR EE2

Troubleshooting steps
Verify that the module is correctly installed. Refer to
KX3-2M/4M installation manual.
Automatically changes the setting of the ACC2 IO menu
entry to OFF (default). If PTT keying via ACC2 is needed,disconnect the device plugged into ACC2, turn powerback on, and set ACC2 IO back to PTT setting. If thiseliminates the ERR message, the external device may beapplying ground to the ACC2 tip contact at all times.
If the module is not actually installed, set MENU:ATU
MD to N O T I N S T . If the module is installed, remove it
and re-install it, making sure both connectors are correctly
lined up with their mating connectors on the RF board.
Turn power off for 10 seconds, then back on. Remove andre-install the KXAT3 option module, making sure both of
its connectors are correctly lined up with their mating
connectors on the RF board. If this doesn’t correct the
problem, replace the module.
Turn power off for 10 seconds, then back on. If thisdoesn’t correct the problem, re-seat the KXBC3 moduleand repeat. If the problem persists, replace the KXBC3.
Turn power off for 10 seconds, then back on. If thisdoesn’t correct the problem, reload MCU and DSP
firmware. If the problem persists, save your configuration
using KX3 Utility, then perform an EEINIT (pg. 46). If
this corrects the problem, restore your configuration using
KX3 Utility. If not, write down all error codes andassociated data values (displayed on VFO A) and contact
Elecraft.
The main microcontroller (MCU) may be defective.
Follow the steps shown for ERR DS1.
EEPROM may be defective. This message may also
appear if power is turned off/on too rapidly, or if the
supply voltage “bounces” during turn-on. If the power
supply is not at fault, follow steps shown for ERR DS1.
47

ERR FW2

Firmware error or EEPROM
configuration error.
d = n n n identifies the type oferror (corrective actions shownat right).

ERR IOA,ERR IOB

RF board I/O expander A or B
unresponsive.

ERR KEY,ERR PTT

Attempt to key the transmitteror activate PTT during poweron sequence. (Note: If ERR
PTT occurs, VOX transmit isdisabled in all modes. Reenable using the V O X switch.)ERR OSCERR RFB

Synthesizer IC unresponsive
RF board may be disconnectedfrom Control Panel board
RF board relay failure (on VFO
A, d = n n n identifies relay #.)Transmit power MOSFET Q6
or Q7 bias out of range
Transmit gain constant out ofrange

ERR RFKERR TX6,ERR TX7ERR TXGERR TXC,ERR TXSERR TXNERR TXOERR TXPERR TOS,ERR TPAERR VOX

Transmit attempt without firstcalibrating TX BIAS in CW(TXC) or SSB (TXS) mode
Transmit attempt without firstnulling the carrier on present
band
Transmit attempt without firstnulling the opposite sideband
on present bandTX gain not calibrated
Synthesizer or power amplifier
temperature sensor out of range
VOX activation detected at
power-on

For d d d = 001, 003, 005, and 007-up (internal errors):
follow steps shown for ERR DS1. 002: VFO data error;
switch to each ham band in turn, from 160-6 m, using
FREQ ENT rather than the band switch. 004: A PC
application has overflowed the KX3’s RS232 port buffer;
reset the application and power the KX3 off/on. 006: Redo the Extended VFO Temp. Compensation procedure.
Turn power off; open enclosure. Make sure the cablebetween the Control Panel board and RF Board is fully
seated at both ends and not damaged. Close the enclosure.
Turn power on. Reload MCU and DSP firmware. If error
codes persist, turn power off, remove all option modules,
and turn power back on. Turn off all associated option
module enables, then turn power off and back on. If thiscorrects the problem, re-install option modules one at atime to see which one may be causing the problem. If
errors persist, the Control Panel or RF Board may have tobe replaced; contact Customer Support.
Usually caused by an incorrect setting of MENU:MIC
BTN for the current microphone, or an external device
shorting the KEY or PTT line to ground, or a shorted
KXPD3 keyer paddle. Turn power off, then disconnect the
KXPD3 (if applicable) and everything plugged into theleft side panel, except for the power supply. Turn powerback on. Plug devices back in one at a time to see which
one caused the error.
Follow steps for ERR IOA.
Follow steps for ERR IOA.
Follow steps for ERR IOA.
Follow steps for ERR IOA.
If this only occurs on one or two bands, there could be a
problem with a band-pass or low-pass filter. Also try redoing Transmit Gain calibration (pg. 33).
Perform Transmit Bias calibration (pg. 33). This is afully-automated procedure that requires no test equipment.
Transmit Carrier calibration must be redone (pg. 34).
This procedure requires a spectrum analyzer and isnormally done only at the factory.
Transmit Sideband calibration must be redone (pg. 34).
This procedure requires a spectrum analyzer and isnormally done only at the factory.
Follow steps for ERR TXC.
Follow steps for ERR IOA.
Usually caused by audio at the mic at power-on, with
VOX enabled for voice modes. Turn power off, thendisconnect the mic. Turn power back on. Turn voice-mode
VOX off or reduce VOX gain.
48

Theory Of Operation
This section includes:§a functional description of the KX3’s RF, control panel, and option PC boards§block diagram of the KX3 (pg. 51)§glossary of selected technical terms (beginning on pg. 52)

Additional information including an FAQ (answers to frequently asked questions) can be found on the Elecraft
web site.

RF Board
The RF PCB (Printed Circuit Board) contains all of the KX3’s RF circuitry as well as low-level baseband (AF)stages in the receive path. The Control Panel (CP) board (following page) generates all digital control signals
for band switching, T/R, signal path routing, etc.
The relay-switched low pass filters are used during both transmit and receive. A few of the filters are dedicatedto one band but most cover two bands. The signal on the antenna side of the filters pass through aforward/reflected power and SWR bridge to the HF-6 meter antenna jack (BNC), or to the optional KXAT3
automatic antenna tuner. Latching relays are used to minimize power consumption.
Transmit/receive (T/R) switching splits the common signal path from the antenna and low pass filters to either
the transmitter power amp or receiver input. It also allows sharing the band pass filters between receive andtransmit. All T/R switching is done with high-power PIN diodes and CMOS switches to facilitate high speedtransitions between receive and transmit.
The synthesized, digitally controlled local oscillator (LO) provides quadrature signals to the transmit andreceive mixers, as well as a reference signal to the optional KX3-2M/4M module. The LO has very good phasenoise performance and can cover a very wide frequency range. Since the KX3 uses a “zero IF” architecture, theKX3’s LO frequency is always very close to the operating frequency.
The RF band-pass filters are used for both transmit and receive. Filters are selected with low-loss CMOS RF
switches. The band pass filters significantly attenuate receive signals at harmonics of the RX frequency,
particularly the odd harmonics.
Following the band pass filters and T/R switching are two RF preamplifiers and an attenuator. These provide
various tradeoffs between RF gain and noise figure (or MDS), as well as local oscillator (LO) isolation. The
latter would be useful in situations where another receiver in close proximity could be tuned to the same
frequency. A problem inherent in most direct conversion (zero IF) receivers is that some LO energy leaks to theantenna and is radiated. This can be a problem when another receiver & antenna is in very close proximity andis tuned to the same frequency. The isolation preamp in the KX3 (RX ISO menu entry) virtually eliminates thissignal leakage.
The RX mixer converts the RF signal to quadrature baseband (AF I and Q signals), which are low-pass filteredand amplified before being passed to the CP board for analog to digital conversion (ADC). I and Q baseband
signals (In-phase and Quadrature) from the mixer are also buffered and sent to the RX I/Q output. This allows
attaching the KX3 to a PX3 Panadapter, or to a PC or other device running SDR software (pg. 26).
The main AF amplifier section also interfaces to the optional KXFL3 filter module that provides narrower
analog filter bandwidths for improved dynamic range performance with nearby strong interfering signals.
The TX AF Amp and TX mixer block converts baseband (AF I and Q) modulating signals to an RF signal
which is then routed to the T/R switching and band pass filters. This signal provides excitation to the 10W
power amplifier. The 10W amplifier (PA) uses a pair of RF power MOSFETs. Temperature monitoring of the49

MOSFETS allows automatic reduction of power if they become too hot during long transmit periods at highpower levels and high ambient temperature.
The optional KXAT3 automatic antenna tuner (ATU) option connects between the BNC antenna jack and the
RF board’s SWR/power bridge and low pass filters. It uses a latching relay-switched “L network” with eight
inductors and eight capacitors capable of matching a wide range of antenna impedances. The KXAT3 also
serves as a preselector for operating frequencies below 160 meters, significantly improving reception in the AM
broadcast band and below.
Another option, the KXFL3 roofing filter module, provides two additional balanced analog filters in the
baseband AF I/Q amplifier path. These are much narrower than the default bandwidth. The result is a significant
performance improvement in rejecting extremely strong interfering signals that are just a few kHz away fromthe received signal.

Control Panel (CP) Board
The CP (Control Panel) circuit board contains all of the KX3’s control circuitry as well as high-level baseband(AF) stages for the transmit and receive paths. It contains two on-board microcontrollers: one to manage theradio (MCU), and another to process all transmit and receive signals digitally (DSP).
The DSP is a 32-bit, floating-point device. All modulation, demodulation, AGC, filtering, equalizing, and othersignal processing functions are handled by this IC.
The incoming baseband (audio) signal from the RF board is provided in low-level phase quadrature, or In-phaseand Quadrature (I/Q). These signals are digitized by a very low power, high-performance analog-to-digitalconverter (ADC), then passed to the DSP for processing.
The baseband transmit signal is likewise provided in I/Q format to the RF board. A dedicated, highperformance digital-to-analog converter (DAC) is used to generate a very clean transmitted signal.
DSP program storage is by means of a 2 megabyte FLASH memory device. This IC also provides storage of
operator messages for the DVR function of the KX3 (pg. 21).
Stereo (two-channel) audio from the DSP is converted to analog signals for use with headphones or dual
external speakers (PHONES jack). The use of stereo allows special processing to help reduce operator fatigue(Audio Effects, pg. 20), and also optimizes dual watch capability (pg. 20), where the signals from VFOs A and
B are routed to the left and right channels. If the internal speaker is used, the audio is monophonic, and isboosted by a separate speaker amplifier IC. Microphone audio (or low level audio from a computer or or othersource) uses another ADC that runs at all times to enable voice-operated transmit (VOX) operation.
The microcontroller unit (MCU) handles all user interface functions for the KX3, including twenty switches
and five shaft encoders. It also handles timing, sequencing, and overall management of the entire radio. The
MCU uses EEPROM (electrically erasable, non-volatile memory) to store operator preferences, message keyer(CW/RTTY/PSK) messages, and control settings. A serial port (ACC1) provides an interface between the
MCU and an attached personal computer (PC), with both RS232 and USB cabling options.
The MCU uses two industry-standard serial protocols to control circuits on the RF board. I2C (pronounced Isquared-C) controls the synthesizer. SPI handles bandswitching, changeover between receive and transmit, etc.
The driver for the liquid-crystal display (LCD) is also controlled via the I2C port.
The KXBC3 battery charger is an optional module that plugs into the CP board. It manages charging of NiMH
AA cells (if applicable). The emphasis on the design is safety, so relatively low charging currents are employed.
The KXBC3 also incorporates a real-time clock (RTC) function, useful for logging and time keeping. The RTC
also allows the KX3 to function like a clock radio, turning itself on at a predetermined time (see the ALARM
menu entry).

50

KX3 Block Diagram51

Glossary of Selected Terms
The following terms are often used in the discussion of amateur radio transceivers and related equipment. All
are directly applicable to the KX3, which is used here to illustrate some of the concepts. A much larger glossaryof terms can be found in the ARRL Handbook and on numerous web sites.
________________
A-to-D or ADC (analog-to-digital converter): An integrated circuit that converts analog electrical signals suchas audio or RF into digital form. The digital signals can then be processed by a digital signal processor, or DSP(see below).
AF, RF, and IF: AF stands for audio frequencies—usually, sounds that you can hear. RF, or radio frequencies,
are the actual frequencies of the radio signals (or TV, or cell phone, etc.). IF, or intermediate frequencies, aregenerally somewhere between RF and AF. In a receiver, it is usually advantageous to convert RF signals to alower IF at which is it more practical to obtain gain or selectivity. These IF signals are then further converted to
AF and amplified further so they can be used to drive headphones or speakers.
Attenuator: A circuit that reduces signals to a safe level for use by subsequent stages in a receiver. The KX3
includes two switchable attenuators, one under control of the user (pg. 13), the other switched in automaticallyas needed (pg. 45, under COR).
ATU (automatic antenna tuner): A device inserted between a transmitter (or transceiver) and an antenna that
establishes an optimal match between the two, thus allowing full power transfer. (See KXAT3, pg. 25.)
D-to-A or DAC (digital-to-analog converter): An integrated circuit that converts digital signals into analog
form, such as audio or RF. Also see DSP, below.
dB (decibel): A measure of signal increase or decrease, or of one signal relative to another signal. In humanterms, one dB represents a “just noticeable difference” between two signals (or a just-noticeable increase or
decrease). Mathematically, dB is derived from the ratio of two signals. Receivers must handle signals over ahuge range—in excess of 100 dB. dBm is a more specific term that means “dB relative to 1 milliwatt.” 1
milliwatt is considered to be a “0 dBm” signal in this case.
DC-to-DC converter: A device that converts one DC voltage into another. For example, the KX3 includes avery efficient DC-to-DC converter that converts 12 V (nominal) at the DC input jack to 3.3 V for use by its lowvoltage circuitry. The advantage of a DC-DC converter is that when it steps voltage down, it steps current up (orvice-versa). In this case, the 300 mA the KX3 consumes at 3.3 V might require only 100 mA at the 12-V powersource.
DSP (digital signal processor): A highly specialized numeric computer, implemented on a single integrated
circuit, that processes signals digitally. Inputs to the DSP must generally be converted from analog to digitalform (see A-to-D, above), while outputs from the DSP must be converted from digital to analog (see D-to-A).
Use of DSP techniques can result in greater versatility and smaller size compared to the equivalent analog
circuitry. The KX3 uses a very advanced, power-efficient DSP.
ESD (electrostatic discharge): An event during which high voltages or currents appear within a radio or otherelectronic device, potentially causing damage. Antennas, control cables, or the operator’s body are all potential
ESD sources. Damage can be avoided through proper handling and grounding techniques.
HF (high-frequency): Signals in the range of 3 to 30 MHz. In amateur radio, HF is also shorthand for 160-10
meters (1.8 to 29.7 MHz), or the “HF bands.” 160 meters actually falls in the MF range (0.3 to 3 MHz). The 6meter band (50-54 MHz) is often included in “HF” transceivers, though it is actually in the VHF (very highfrequency) range of 30-300 MHz.
IMD (intermodulation distortion): Unwanted signal products that are created in the various stages of areceiver or transmitter. If all stages were entirely “clean,” there would be no IMD. In reality, every stage
contributes some distortion, with the amount of distortion being proportional to signal level. Radio designers go
52

to great lengths to minimize distortion, trading off circuit cost and complexity against the benefit of reduced
interference.
Keyer: A device that partially automates the sending of Morse code, allowing for faster code speeds. The KX3
has a built-in keyer function, as well as an optional attached keyer paddle (KXPD3, pg. 25).
Linear power supply: A power supply that provides a well-regulated DC output voltage using analog regulator
circuitry. An analog regulator uses continuous voltage feedback, and can be designed to generate virtually nonoise at radio frequencies, at the expense of power-conversion efficiency. Linear power supplies also typicallyincorporate a transformer and large filter components (capacitors and inductors), resulting in larger and heavier
packages than switching power supplies (see below).
MCU (microcontroller unit): A computer or controller usually integrated onto a single integrated circuit. A
modern amateur transceiver usually has one main MCU that controls most radio functions. It may have othersmaller MCUs or co-processors that perform specific functions. The KXBC3 option module has its own MCU(pg. 25). The DSP in the KX3 is another specialized co-processor (see DSP, above).
MDS (minimum discernable signal): A measure of a radio’s sensitivity, expressed in dB (decibels) relative to
1 milliwatt (0 dBm). For example, the user of a KX3 with the 20-dB preamp turned on, can typically copy a CW
signal at about -137 dBm, or 137 dB below 1 milliwatt. MDS is dependent on the receiver bandwidth, with 500
Hz normally used for standardized measurements.
Panadapter: A special-purpose spectral display that shows signals over a small or large portion of a given
band. The panadapter samples the transceiver’s I.F. output voltages, then mathematically derives the spectral
display using a fast-Fourier transform (conversion from time domain to frequency domain). In the case of the
Elecraft PX3, a 2 kHz to 200 kHz range can be displayed, with both a spectral plot and a “waterfall,” whichshows the history of signals over several seconds’ time.
Preamp: A pre-amplifier that increases RF signals to a higher level for use by subsequent stages in a receiver.
A preamp is generally designed to contribute little noise of its own, so that it improves the noise figure of theradio (also see MDS). The KX3 includes two different preamps for use in different situations (pg. 13).
Roofing filter: A filter built with analog components that rejects some out-of-band signals which could cause
overload or distortion. The roofing filter appears ahead of the A-to-D converter and DSP in a receiver’s signal
chain, protecting them to some degree. The KX3 has an optional dual roofing filter (see KXFL3, pg. 25.)
SDR (software-defined radio): A radio that performs signal modulation, demodulation, filtering, and otherfunctions in software. The software might execute internally in a dedicated DSP IC, as in the Elecraft K3 or
KX3, or externally in a general-purpose computer (pg. 26).
Switching power supply: A power supply that provides a regulated DC output voltage by rapidly injecting
current pulses into its load. The duration of the pulses varies with the required load current at any given instant.
The switching rates used in this type of regulator can be in the hundreds of kHz or even MHz, and their period
can vary widely. This is why such power supplies often generate RFI (radio-frequency interference) or hash if
not well-shielded and filtered. Switching supplies are typically much smaller than linear supplies (see above) fora given output current, and are used in most PCs and other electronic equipment because of the reduced
manufacturing cost. However, much of the RFI heard in amateur receivers originates from switching supplies innearby gear or even from neighboring houses. The supply that powers the radio itself is especially critical, and alinear supply will often provide better results.
VFO (variable frequency oscillator): A signal source used to select a radio’s operating frequency. The KX3’s
large knob controls VFO A, while a smaller knob controls VFO B (see Using VFOs A and B, pg. 11).

53

Specifications
GENERAL
Frequency Range

310 kHz - 32 MHz and 44-54 MHz; 120-168 MHz with KX3-2M; 65-72 MHz with
KX3-4M. Transmit exclusions vary by country. See receiver sensitivity note below.

Frequency Stability+/- 1 ppm typical over 0-50 C. An extended temperature compenstation procedure canbe applied for improved stability (refer to our KX3 web page).

Antenna

50 ohms; HF: BNC jack; 2 and 4 m: SMA (supplied with KX3-2M/4M option)

Modes

USB, LSB, AM, FM, CW, DATA; built-in PSK/RTTY/CW text decode/display

VFOs

Dual VFOs (weighted VFO A knob); 150+ memories; scanning/channel hopping

Accessory I/O (ACC2 Jack)KEYLINE: 30 V, 100 mA max, open drain; GPIO: 0-3 V (see ACC2 IO menu entry)

Supply Voltage
and Current

8 V min, 15 V max. 1 to 2 A typical in transmit; 150 mA minimum receive, typical(backlight off, preamp off, no signal)Size and Weight

Size: 3.5 x 7.4 x 1.6” (8.8 x 18.8 x 4.1 cm); weight: 1.5 lbs. (0.68 kg) less options

RECEIVER*
Sensitivity (MDS),

500-Hz bandwidth-138 dBm (typ.), 20 dB preamp; -140 dBm typ. on 6 m with 30-dB preamp; -144 dBm(typ.) on 2 m/4 m. Notes: (1) Sensitivity rolls off below 1.8 MHz due to protective
high-pass filtering; preamp-on MDS @ 0.55 MHz, 94 dBm (typ.). (2) Image rejection
in 0.5-1.5 MHz range can be improved by installing KXAT3 option (see MENU:ATU
MD). (3) With KX3-2M/4M modules, sensitivity falls off outside the ham bands.

Image and I.F. Rejection

55-70 dB typ. (varies with filter settings, mode, and band)

Audio Output

Internal speaker, 0.5 W typ.; headphones/ext. speaker jack, 0.1 W/channel (stereo)

Receive Features

8 band RX EQ, tunable I.F. passband width/shift, optional roofing filters (KXFL3)

TRANSMITTER*
Output Power

10 W PEP, 160-15 m; 8 W PEP, 12-6 m; KX3-2M/4M: 3 W, 144/70 MHz.
Supply voltage of 11 V or higher (on key-down) required for settings above 5 W.
5 W or less recommended for high-duty-cycle modes (FM, AM, DATA). Power willautomatically be reduced if PA temperature or current limits are exceeded.

Internal ATU (KXAT3)

8 L/8 C network; matching range typ. 20:1 or higher. Rated power: 15 W.
Insertion loss (bypass mode): < 0.5 dB, 160-10 m; < 1 dB, 6 m.

Voice Transmit Features

Split-band, adjustable speech compression; 8-band TX EQ; VOX; 2 DVR messages

CW Transmit Features

Full and semi CW break-in with adjustable delay; diode T/R Switching; 6 messages

Carrier Suppression> 50 dB typ.

Harmonic / Spurious Outputs> 50 dB below carrier @ 10 W (> 60 dB on 6 meters)

CW Sidetone/Transmit offset

400-700 Hz, adjustable (receive filter center frequency tracks sidetone pitch)* Specifications apply only within ham bands except as noted. All measurements taken with 13.8 VDC supply.
54

Customer Service and Support
Technical Assistance
You can send e-mail to KX3support@elecraft.com and we will respond quickly – typically the same day
Monday through Friday. If you need replacement parts, send an e-mail to parts@elecraft.com. Telephone
assistance is available from 9 A.M. to 5 P.M. Pacific time (weekdays only) at 831-763-4211. Please use e-mailrather than calling when possible since this gives us a written record of the details of your problem and allows us
to handle a larger number of requests each day.

Repair / Alignment Service
If necessary, you may return your Elecraft product to us for repair or alignment. (Note: We offer unlimited email
and phone support, so please try that route first as we can usually help you find the problem quickly.)
IMPORTANT: (1) REMOVE BATTERIES before shipping. (2) You must contact Elecraft before mailingyour product to obtain authorization for the return, what address to ship it to and current information on repair
fees and turn around times. (Frequently we can determine the cause of your problem and save you the trouble ofshipping it back to us.) Our repair location is different from our factory location in Aptos. We will give you theaddress to ship your kit to at the time of repair authorization. Packages shipped to Aptos without authorization
will incur an additional shipping charge for reshipment from Aptos to our repair depot.

Elecraft 1-Year Limited WarrantyThis warranty is effective as of the date of first consumer purchase (or if shipped from the factory, the date theproduct is shipped to the customer). It covers both our kits and fully assembled products. For kits, before requesting
warranty service, you should fully complete the assembly, carefully following all instructions in the manual.
Who is covered: This warranty covers the original owner of the Elecraft product as disclosed to Elecraft at the timeof order. Elecraft products transferred by the purchaser to a third party, either by sale, gift, or other method, who is
not disclosed to Elecraft at the time of original order, are not covered by this warranty. If the Elecraft product is beingbought indirectly for a third party, the third party’s name and address must be provided at time of order to ensure
warranty coverage.
What is covered: During the first year after date of purchase, Elecraft will replace defective or missing parts free ofcharge (post-paid). We will also correct any malfunction to kits or assembled units caused by defective parts andmaterials. Purchaser pays inbound shipping to us for warranty repair; we pay shipping to return the repaired
equipment to you by UPS ground service or equivalent to the continental USA and Canada. For Alaska, Hawaii, andother destinations outside the U.S. and Canada, actual return shipping cost is paid by the owner.
What is not covered: This warranty does not cover correction of kit assembly errors. It also does not cover
misalignment; repair of damage caused by misuse, negligence, battery leakage or corrosion, or builder modifications;or any performance malfunctions involving non-Elecraft accessory equipment. The use of acid-core solder, watersoluble flux solder, or any corrosive or conductive flux or solvent will void this warranty in its entirety. Also notcovered is reimbursement for loss of use, inconvenience, customer assembly or alignment time, or cost ofunauthorized service.
Limitation of incidental or consequential damages: This warranty does not extend to non-Elecraft equipment orcomponents used in conjunction with our products. Any such repair or replacement is the responsibility of thecustomer. Elecraft will not be liable for any special, indirect, incidental or consequential damages, including but notlimited to any loss of business or profits.

55

Index
ACC1 and ACC2 Jacks, 5Advanced Operating Features, 17
AF Gain Control, 12
AF Limiter, 35
AFSK A Mode, 18
AFV, 22
AFX (Audio Effects), 20, 29
AM Mode, 10, 15, 29
Analog To Digital Converter (ADC, A-to-D), 52
Antenna, 33
Antenna Jacks, 6
Antenna Recommendations, 6Anti-VOX, 15
Attenuator, 13, 52
Audio Effects (AFX), 20, 29
Audio Peaking Filter (APF), 13
Auto Info (AI Mode), 37
Auto Power-Off, 29
Automatic Antenna Tuner (ATU), 6, 14, 36, 52
Auto-Notch, 13
Auto-Spot, 13, 16
Band Mapping, 30, 37
Band Selection, 10
Bar Graph, 8Batteries, 4, 23, 24, 29, 37
Birdies, 46
Block Diagram, 51
Break-In Keying (QSK), 14, 16
Calibration Procedures, 31
Carrier Operated Relay (COR), 45
Channel Hopping, 17
Charging Batteries, 24
Clock/Calendar, 41
Code Practice, 16
Configuration, 29, 46
Control Groups, 4
Cross-Mode Operation, 21
Crystal Filter Center Frequency, 54
Current Drain, 11
Customer Support, 55
CW Keying Weight, 16, 21, 37

CW Mode, 16
CW Reverse, 8
CW, Break-In (QSK), 14, 16
CW, Off-Air Keying, 35
CW, Sending in SSB mode, 37
CWT, Tuning Aid, 13, 16
CW-to-DATA, 16
DATA A Mode, 18
DATA Mode, 18
Data Modes, 18
DATA Reverse, 8Date, 30
dB, decibel, 52
dBV, 22
DC-to-DC converter, 52
Digital Signal Processor (DSP), 52
Digital To Analog Converter (DAC, D-to-A), 52
Digital Voice Recorder, 21
Direct Frequency Entry, 10
DTMF (dual-tone, multi-frequency), 15
Dual Watch, 20
EEINIT, 46
Electrostatic Discharge (ESD), 4, 6, 52
Error Messages (ERR nnn), 44, 47
Filter Graphic, 8
Firmware Upgrades, 25
FM, 38FM Deviation, 38
FM Mode, 10, 15, 29
Frequency Memories, 17
Frequency Range, 54
Front Panel, 4
FSK D Mode, 18
Headphones, 5
HI CUR Warning, 45
HI RFI Warning, 45
HI SWR Warning, 45
High Frequency (HF), 52
I/II, 8
Iambic Keying, 30, 37
Intermodulation Distortion (IMD), 52
56

KDVR3, 21
Keyboard, 28Keyer, 14, 53
Keyer Paddle, 4, 16, 37
Keying Weight, 16
KX3 Utility PC Application, 25, 28, 46
KX3-2M, 25
KXAT3, 25, 29, 36
KXBC3, 24, 25, 29
KXFL3, 25, 29
KXPA100, 14, 29
KXPD3, 25, 29
LCD Test, 38
Low Battery Warning, 29, 44
Low-Pass Filter, 48
Memories, 17Memory Label, 17
Menu Functions, 35
Menu Settings, 9, 29
Message Record/Play, 16
MH3, 25
Microcontroller Unit (MCU), 53
Microphone, 5
Microphone Gain Control, 14, 15
Microphone Settings, 30
Minimum Discernable Signal (MDS), 53
Mode Selection, 10, 38
Monitor and Sidetone Level Control, 12Noise Blanker, 13
Noise Reduction, 13
Notch Filtering, 8, 13
Option Module Enables, 29
Options, 25
OSC, 22
PA temperature, 22
Parameter Initialization, 46
Parameter Save/Restore, 47
Passband Tuning Control (PBT I/II), 12
PF1, PF2, 19
Pot Test (SW TEST), 40
Power On/Off, 9Power Output Control, 14Power Supply, 4

Preamp, 8, 13, 30, 53
Programmable Function Switches, 19
PSK D Mode, 18
PSK31, 18
PTT (Push To Talk), 15
QSK, 14, 16
Quadrature Outputs (RX I/Q), 5
Quasi-Stereo (AFX), 20, 36
Quick Memories, 17
Quick-Start Guide, 7
Real Time Clock, 30
Receive Settings, 12Reference Oscillator, 31, 39
Remote Control, 28
Repeater Offset, 15, 39
Repeater Operation, 15
REV switch, 19
RF Board, 49
RF Gain Control, 12
RIT, 42
RIT/XIT Offset, 11, 42
Roofing Filter, 12, 53
RS232, 28, 39
RTC, 30
RTTY, 18
RX EQ, 20, 39, 41, 46
Scanning, 17
SDR Applications, 26
Self-Test, 25
Serial Number, 40
Sidetone, 14, 16
S-Meter, 8
Software Defined Radio (SDR), 53
Speaker, 5, 20
Specifications, 54
Speech Compression (CMP), 14
SPKRS=1 Warning, 45
SPLIT and Cross-Mode Operation, 45
Split and XIT, 19
Squelch Control, 12, 15
SSB +CW, 37
SSB Mode, 15
SSB/CW VFO Offset, 21
57

Standing Wave Ratio (SWR), 6
Switch Test, 40
Switch Tones, 30, 40
Synthesizer, 51
TCXO, 54
Tech Mode Menu Entries, 41
Terminal Emulator, 28
Text Decode and Display, 16, 19
Theory Of Operation, 49
Time, 30
Transmit Gain Calibration, 33, 41
Transmit Inhibit, 21
Transmit Noise Gate (Voice Modes), 21, 42
Transmit Settings, 14
Transverter, 21
Transverter Control, 42
Transverter Operation, 21

Troubleshooting, 44
Tune Power, 30, 41
Tuning Rate, VFO, 30, 42
TX EQ, 20, 41
TX LED, 25, 45
Universal Serial Bus (USB), 5
Variable Frequency Oscillator (VFO), 53
VFO B Parameter Displays, 11, 22
VFO Counts per Turn, 42
VFO lock, 11
VFO Setup, 30
VFO Tuning Controls, 11, 30, 42
Voice Modes, 15
VOX, Voice Modes, 14, 15, 30
Warranty, 55
Wattmeter, 42
XIT, 19, 42

58