ELECRAFTÒ KX2
POCKET-SIZED, 80-10 M SSB/CW/D ATA TRANSCEIVEROWNER ’S MANUAL
Rev. A8, June 6, 2019

© 2019, Elecraft, Inc.

All Rights Reserved

Contents
AM Mode 22

Advanced Operating Features 23

Introduction 4

Special VFO B Displays 23
Frequency Memories 24
Scanning 24
Audio Effects 25
Dual Watch 25
Programmable Function Switch (PFn) 25
Receive Audio Equalization (RX EQ) 26
Transmit Audio Equalization (TX EQ) 26
SSB/CW VFO Offset 26
Data Modes 27
Text Decode And Display 29
Split Operation 30
Digital Voice Recorder (DVR) 30
Transmit Noise Gate 31
Cross-Mode Operation 31
Custom Power-On Banner 31
Logging (CW/Data Modes) 32
Transverter Bands 32

Key to Symbols and Text Styles 4

Installation 5
Operating Position 5Power Supply 5Internal Battery 6
Utility Mounting Points (Bottom Cover) 7
CW Key/Keyer Paddle 8
Headphones and Speakers 8
Internal Microphone 8External Microphone 8
Computer/Amp Keying (ACC) 9
Auxiliary Outputs (AUX) 9
Program/Test (PGM) 9
Antennas 10

Control Panel Reference 12
Display (LCD) 13

Basic Operation 14

Options and Accessories 33

Getting Started 14
Band Selection 15
Mode Selection 15
VFO A and B 16
Incremental Tuning (RIT and XIT) 16
Special VFO B Displays 16
Receive Settings 17
Transmit Settings 19
SSB Mode 20
CW Mode 21

Firmware Upgrades 34
Remote Control of the KX2 35
Configuration 36
Option Module Enables 36
Menu Settings 36

Calibration 38
Reference Frequency 38
2

Receive Opposite Sideband 39
Transmit Bias 39
Transmit Gain 39
Transmit Carrier 40
Transmit Opposite Sideband 40

Menu Functions 41
Troubleshooting 54
Parameter Initialization (EEINIT) 58
Error Messages (ERR nnn) 59
Scrolling Alert Messages 62

Theory Of Operation 63
Glossary of Selected Terms 66

Specifications 68
Customer Service and Support 70
Index 723

Introduction
The Elecraft KX2 is a pocket-sized, 80-10 m, SSB/CW/data transceiver designed specifically for portable,
mobile, and hand-held operation. Weighing just 13 oz. (0.35 kg), it’s the perfect “grab and go” HF radio.
Despite its small size, the KX2 is a full-featured HF transciever, with up to 10 W output. Its powerful digital
signal processor (DSP) provides dual watch, built-in PSK and RTTY modes, digital voice recorder, stereo
audio, noise reduction, and various filtering functions. The KX2 can be configured as a complete station,with internal antenna tuner (ATU), whip antenna (AX1), attached keyer paddle (KXPD2), and internal
battery (KXBT2). Current drain is about 150 mA, far lower than other DSP-based portable transceivers.
Since the KX2 is a software-defined-radio (SDR), you’ll be able to add new features via free firmware
upgrades. For mobile and home use, you can boost the KX2’s output to 100 watts with the optional
KXPA100 amplifier. The KXIO2 option adds a real-time clock, as well as two outputs that can be used forantenna switching or other applications.
When your next adventure begins—whether at home or in the field—your KX2 will be ready.
73,
Wayne, N6KR
Eric, WA6HHQ

Key to Symbols and Text Styles

LSB.

Important – read carefully

XMIT

Tap function of a knob or switch

Operating tip

TUNE

Hold function (hold switch 0.5 s)

Icon or text shown on the display

MIC

Enter keypad function

BKLIGHT

Locked (VFO or menu parameter)
4

Rotary control (knob) function
Menu entryPower Supply

Installation

For fixed-station use, a low-noise 12-14 VDC power
supply or battery is recommended. For lightweightportable operation, an internal battery can be used.

CAUTION§§§§Be careful when plugging in cables. Avoid
sideways pressure that might damage the jacks.
Avoid direct exposure to rain or snow (the KX2
is not waterproof).
Avoid operating at very high temperatures.
Prior to opening the enclosure, touch a grounded,
unpainted metal surface to avoid static discharge.

See next page for internal battery installation.
Batteries or power supplies can be plugged in frominside, outside, or both. The internal and external DC
jacks are identical, and are diode-isolated from eachother. The higher voltage will power the transceiver.
Power output varies with supply voltage.

Operating Position
As shown below, the tilt leg on the back of the KX2 canbe used to optimize the viewing angle. Loosen the rear
thumbscrew to adjust the tilt leg. The KX2 can also be
operated hand-held, either vertically or horizontally.

(+)

An external power supply or battery can be connectedto the 9-15 V jack on the left side panel (see above).
The center pin is (+). The plug can be a Switchcraftmodel S760 or similar (2.1 mm aperture, 5.5 mm dia.).
The white striped wire on the supplied cable is (+).
Trim the cable to the desired length.
5Internal Battery
The KXBT2, shown here installed,
is an 11 V, 2.6 Ah li-ion battery
with protective circuitry.

Note: Speaker wires arerouted between the small
band-pass filter board

and the chassis.

Battery installation:
•
•

•
•
•
•

Loosen the two thumb nuts at
the ends of the bottom cover.
Rotate the cover open,
keeping speaker wires
captivated in the location
shown at right.
Place the battery as shown andplug it into the internal jack.
Make sure battery wires aretucked inside, beside the plug.
Install the bottom cover.
Tighten the two thumb nuts
firmly to keep the bottom
cover in place.

Battery removal:•••

Open the bottom cover as
described above.
Pull the battery plug out
slowly, using the provided
nylon pull-loop. Do not pullon the battery pack wires.
Replace the bottom cover andtighten the thumb nuts firmly.
6

Using the Battery Safely

Amp Hour Metering

Misusing a lithium-ion battery may cause it toget hot, rupture, or ignite and cause serious injury;or result in loss of performance and shortened life.

The KX2 includes an amp hour meter function thatallows you to better estimate remaining battery life.
See pg. 16 for the associated special display function,
as well as the AMP HRS menu entry.

The KXBT2 battery pack weighs only 4.8 oz, and canprovide up to 8 hours of typical transceive operation
and up to 10 W power output. To ensure safe
operation, please take a moment to read theinformation sheet supplied with the battery.

Preserving Clock Time During Charging
The KXIO2 option module includes a real-time clock(RTC), useful for logging (see LOGGING menu
entry). RTC circuitry is powered by the battery or
power supply connected to the KX2 (internal orexternal).

The pack is fitted with a 2.1 mm DC barrel plug. The
KX2 has two DC barrel jacks: one inside, and one on
the left side panel. These jacks are isolated from eachother, but either can power the KX2. You can plug in
an internal battery and an external supply, and theradio will operate from whichever is higher in voltage.

When no power supply or battery is connected, the
RTC’s time registers are preserved for up to 2 hours by
a supercapacitor on the KXIO2. In most cases thisallows sufficient time to remove the battery from the
KX2, charge it, and reinstall it without losing the time
setting.

Battery Charging
The battery must be charged using only thematching KXBC2 smart-charger.

Utility Mounting Points (Bottom Cover)

To charge the battery, you must first remove it as
described on the previous page. It cannot be charged
while inside the KX2. The power jack on the left sidepanel is isolated from the internal power jack, andcannot supply power to the battery.

The KX2’s bottom cover has two threaded fasteners(4-40 PEM nuts) for light-duty applications. For
example, they could be used to attach the transceiver toa clipboard for field logging, or for storage of acounterpoise wire (see pg. 10, right column).

Plug the battery into the jack on the charger, then plugthe charger into a 120 VAC outlet. The charger’s LED
will be red during charging, and GREEN when charge
is complete. A full charge cycle typically takes 1 to 2
hours depending on the state of charge.

CAUTION: These fasteners are not intended
for use with a mobile mount. Also, do not allow
screws or other hardware to protrude more than0.1” into the interior of the KX2.
7

CW Key/Keyer Paddle

Internal Microphone

The KX2 has two CW keying inputs:

For emergency or hand-held use, the KX2 includes abuilt-in mic, located to the left of the AF/MON control.
(There’s a small hole in the panel at this location.) The
built-in mic is automatically turned on when no
external mic is plugged in. Tap X M I T to transmit.

Attached Keyer Paddle: An Elecraft KXPD2 (orKXPD3) keyer paddle can be attached at the front of
the KX2 via two thumb screws. Use the CW KEY2
menu entry to reverse the dot/dash sides.

To prevent acoustic feedback, the transmit voice
monitor function (MON) is disabled when using theinternal mic with the internal speaker.

KEY Jack: This jack can be used with any hand key,
keyer paddle, or other keying device, as configured by
the CW KEY1 menu entry.

External Microphone

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

The 3.5 mm MIC jack is compatible with the ElecraftMH3 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 .

Headphones and Speakers
The 3.5 mm PHONES jack accommodates
headphones or one or two externally amplified
speakers. Mono or stereo plugs can be used. Stereo
audio allows the use of dual watch and audio effects(pg. 25).

MIC Jack Pinout

Built-In Speaker: The speaker, located on the bottom
cover, sounds best when the tilt foot is used.

Ring2: Logic ground

Sleeve: Shield groundRing1: PTT/UP/DN

Headphones or external speakers will provide
greater bass response than the internal speaker.

Tip:

Mobile installations: For mobile use, amplified
mobile speakers or an aux input on your car’s stereo
can be connected to the PHONES jack. Anotheralternative is to use a device that retransmits the KX2’saudio output in the FM broadcast band.

Mic audio

The KX2 will work with many other mics, including“mini” mics intended to plug directly into a computer.
Refer to the MIC BIAS and MIC BTN menu entries to
set up the KX2 for use with your mic or headset.
8Computer/Amp Keying (ACC)

Amplifier Keying
The ACC jack provides a key out signal (Ring 2
contact, shown at left). Key out goes low duringtransmit, and can be used for transmit/receive
switching of linear amplifiers and transverters. For
keyline voltage and current limits, see Specifications.

The 3.5 mm accessory jack (ACC) facilitates firmware
updates and remote control of the KX2 via a computer,and/or connection to an Elecraft KXPA100 amp. In
either case, a standard stereo plug can be used (seesleeve, ring 1, and tip connections below). The
supplied KXUSB cable can be used for this purpose.

If the key out signal is not required, a regular stereo
plug can used (3-circuit). This will short the key out
signal to the sleeve (ground), but will not cause any
damage or consume additional current.

ACC Jack Pinout

An Elecraft KX2 Accessory Cable (KX2ACBL) canbe used to break out the computer control and key out
signals separately. These can then be connected to bothan Elecraft KXPA100 ampflier via its supplied cable.

Sleeve: Ground
Ring 2: *Key Out
Ring 1: TX Data
Tip:

Auxiliary Outputs (AUX)

RX Data

If the KX2 is fitted with a KXIO2 (pg. 33), then a 2.5
mm AUX jack will be available. This jack provides
two general-purpose outputs that can be programmed
on a per-band basis to control equipment such as anantenna switch or transverter. On the connector, thesleeve is ground, tip is AUX 1, and ring is AUX 2.

* For external ampflier keying, the ACC jack’s key out
signal (on Ring 2) may also be needed, as described atright. In this case a 4-circuit (TRRS) plug is required.
Computer Applications
KX2 Utility is required for firmware configuration andupdates (pg. 34). The utility program also provides a
CW/data terminal function. Our Elecraft Frequency
Memory Editor can be used to set up frequency
memories.

Program/Test (PGM)
This jack is reserved for Elecraft factory test use.

Many logging, contesting, and control programs areavailable from third parties. If the KX2 is not
specifically supported, try using Elecraft KX3 or K3.
9

Antennas

At right, a KX2 is shown in hand-held orientation
with a telescoping whip antenna. An Elecraft AX1
or similar lightweight whip is recommended.
(Such antennas are electrically short, making
contacts more challenging. Best results will
be obtained on 20 meters and higher.)
When using a whip antenna, you’ll also need acounterpoise wire, shown here attached via
a mini-banana plug (Elecraft model
KX2GNDPLUG). A length of about
13 feet is a good compromise for 20-10
meters. This is sometimes called a“trailing ground” by those who operatepedestrian mobile (/PM). If you stepon the counterpoise wire, or get it
snagged, the mini-banana plug
will pull out safely, avoiding
damage to the KX2.

General information on antennas can be found on thenext page. Here, we show two examples of antennas
for portable operation that can be set up quickly.
The illustration at left shows a simple wire antennaconnected to a KX2 via a BNC-to-binding post adapter(Elecraft BNC-BP or equivelant). The wire tied to thered post (antenna hot lead) is attached to a tree or othertall support. The wire tied to the black post (radio
chassis ground) is the equally important counterpoise,
which is typically laid on the ground.
A length of about 25 feet for each wire, matched to the
KX2’s output using an antenna tuner (see ATU, pg. 11)
will typically provide good performance on 40-10 m.
(Without an ATU, resonant lengths are required foreach band.) This antenna is ideal for outings where allgear must fit into a small bag (e.g, our model CS-40).
Wire to tree orother support

BNC-to-binding
post adapter

Mini-banana plug
Counterpoise
Wire

10

Counterpoise
WireGeneral Antenna Information

Feedline: When using low power, antennas can often
be directly connected to the KX2 without any coax orother feedline. This is shown in both of the simple
portable antennas on the previous page. However,balanced antennas such as dipoles and inverted Vs willfunction better when their feed point is physically well
above ground.

An antenna must be connected to the BNC jack via
either coax or an adapter. If an antenna tuner is not
used (either an external tuner or an internal KXAT2),
then a resonant antenna having a 50 ohm(approximate) load impedance on each band ofoperation is required. Examples can be found in the
ARRL Antenna Handbook and other sources. A coaxfed inverted “V” or dipole can be very effective.

Resonant antennas (those which are cut to length for agiven frequency) are typically fed with 50 ohm coax.
RG-174 is a good choice when light weight is required.
Random-length antennas can be fed with twin-lead,then connected to a balun (balanced-to-unbalanced
converter), such as the Elecraft BL1 or BL2. The balun
can then be connected directly to the transceiver (if aninternal ATU is used) or to an external ATU.

SWR: One measure of how close an antenna is toresonance is its SWR (standing wave ratio). The KX2
displays SWR when you use the T U N E switch (pg.
19). An SWR of 1:1 (1 . 0 - 1 on the KX2’s display) is
considered a “perfect” match. To ensure safe operation,
the KX2 reduces power output if SWR is too high.

Ground and Counterpoise Systems: A ground or
counterpoise is needed with many antennas. The ARRL
Antenna Book provides examples. This is definitely
needed when you use a whip, vertical, or random wire.

Using An Automatic Antenna Tuner (ATU): An
ATU will allow the KX2 to “see” a good match inmany cases (i.e., a low SWR) even with non-resonant
antennas. This allows the transmitter to deliver fullpower, and can improve receiver sensitivity. An ATU
may allow one antenna to be used on multiple bands.

The ground or counterpoise can be connected to theKX2 via the bottom cover thumb nuts or to the outershield of the BNC jack. There’s also a hole in the left
side panel, identified by a ground symbol, that is sized
for a mini-banana plug. This is ideal for a quickdisconnect trailing ground wire used during pedestrian
mobile operation. See example on previous page.

You can use an external or internal ATU. The KXAT2(ATU option, pg. 33), stores matching data for each
band; retuning takes less than 1 second. Data sets areprovided for home/field use (MENU:ATU DATA).
Antenna Wire: Insulated, stranded wire works wellfor portable antennas. We recommend #26 “Silky”
from The Wireman (catalog #534). To avoid kinks,
wire can be wound in a figure-8 pattern. For tossing
wire into tree branches, attach a 1 to 2 oz. weight (suchas stainless-steel hex nut) to the end of the wire.

For improved performance, use at least one 1/4wavelength radial for each band when possible.
Adding more radials on a given band will further
reduce losses, especially when transmitting.

11

Control Panel Reference(For details, refer to page numbers shown in parentheses)

Power ON/OFF: Hold both the R A T E and A / B switches for 2 seconds (see “ON” label below the VFO A knob).
Tap / Hold Functions, e.g. P R E / N R : Tap to use the function labeled on or above a control; hold ½-sec for the function labeled below it.
Numeric Keypad: Twelve of the switches and knobs form a keypad (0-9/decimal/enter) for use with F R E Q , etc.

InternalMic

Receive
A F / M O N AF gain (17);tone/monitor level (17)N B Noise blanker (18)Transmit
KYR-SPT/MIC

VFO A / Band / Mode

VFO B / Misc.

D A T A Data mode (27)

M O D E CW/SSB (15)Keyer (19); Spot (21); Mic gain (19) T E X T Text decode (29)R C L / S C N F. recall

tuning (16);VFO B (16)P W R Power level (19)O F S / B Coarse VFO

M S G Msg play (19, 30)(24), Scanning (24)

C L R Clear RIT (16)R E C Msg record (19, 30)

B A N D Band (15)R I T Receive offset (16)P F n Prog. switch functions (25)

R A T E VFO tuning (16);

S T O R E F. store (24)

S P L I T Split RX/TX (30)X M I T TX/PTT (19)T U N E CW carrier (19)ON/OFF (with A / B )F R E Q Freq. entry (15)A / B A/B swap (16)
A > B A>B copy (16)

D I S P Special disp. (23)M E N U Menu (14)P R E Preamp / attenuator (17)A T U ATU tune (19)N R Noise reduction (18)F I L / A P F - A N Filtering(17); APF (18); auto-notch (18)12

Display (LCD)(For Details, refer to page numbers shown in parentheses)

RX: S-meter and CW tuning aid (18);
TX: SWR/RF output or compression/ALC (19)VFO Icons:
Shows that a VFO is locked.
T X icon points to the transmit VFO, A or B (30).
VFO A

X F I L (F L 1 only in KX2)

VFO BFilter Passband Graphic (17):N T C H Auto-notch (18); I / I I (not used)

Mode Icons

Other icons:
CWT

VOX
QSK
NB
NR
ANT

CW/data tuning aid on (MENU:CWT, 18)
Message play/rec ( M S G / R E C , 19, 30), or
logging enabled (MENU:LOGGING)
VOX enabled (MENU:VOX MD, 20, 21)
Full break-in CW (MENU:VOX DLY,21)
Noise blanker on (N B , 18)
Noise reduction on (N R , 18)
KXPA100 antenna (19)

Automatic RX attenuation in effect (17)A T T Attenuator on ( P R E , 17)
P R E Preamp on ( P R E , 17)
A T U ATU enabled ( A T U , 19)
RIT
RIT on ( R I T , 16)
XIT
XIT on (MENU:XIT, 16)
S U B Dual-watch enabled (MENU:DUAL RX, 25)
S P L T Split mode in effect (S P L I T , 30)
RX

13

AF Gain and other Knob Functions

Basic Operation

Each small knob has two primary functions. For
example, A F / M O N normally controls receiver AF
gain. The setting is displayed in the VFO B area duringknob rotation. Tapping this knob briefly switches tothe MON function (sidetone or voice monitor level).
Holding the knob—pushing it for over 0.5 seconds—
switches to its secondary function,
N B (pg. 18).

This section describes basic KX2 features. Onceyou’ve mastered these, you’ll be ready to explore
Advanced Operating Features (pg. 23) including
built-in text decode, memories, and dual watch.

Getting Started

Knobs may also be used in conjunction with nearby
switches. For example, if you tap D I S P , rotating
O F S / B selects special VFO B displays (pg. 23).

Before using the KX2, you’ll need to connect a power
supply and an antenna. See Installation (pg. 5).

Turning the KX2 On/Off

Using the Configuration Menu

To turn the KX2 on or off, press and hold the R A T E
and A / B switches simultaneously for about two
seconds, then release. The switches are identified by an“ON” label below the large knob (VFO A). This dualswitch power on/off method reduces the likelihood ofaccidental power-on in a backpack or carrying case.

To access the menu, hold M E N U until the
BKLIGHT (LCD brightness) menu entry appears in the
VFO B area. The setting appears in the VFO A area.
To change a setting, rotate VFO A (large knob). In thecase of BKLIGHT, this selects backlight O N or O F F .

Always turn the KX2 off as described above
before turning off or disconnecting the powersource. This will ensure that settings are saved.

To scroll through menu entries, use the small knob
above the menu switch, O F S / B . To exit the menu,
tap D I S P .

Switch T A P and H O L D Functions

While in the menu, holding M E N U for ~3 seconds
displays information about the current menu entry.

All KX2 switches have two functions:§Tap to activate the function labeled on a switch,e.g. R A T E§

Hold for about 0.5 second to activate the function
labeled below a switch, e.g. F R E Q

Configuration and Calibration Functions
Once you’ve mastered the menu, you should review
your KX2’s Configuration settings (pg. 36). The
menu is also used for factory Calibration (pg.38).

14

Band Selection

Direct Frequency Entry

The KX2 transmits and receives in the 80-10 m
amateur bands. It also provides general coverage
receive from 0.5 to 32 MHz, which includes the AM
broadcast band and 160 m.. (Sensitivity and image
rejection are reduced below 3 MHz; see
Specifications, pg. 68.)

A subset of the controls functions as a numeric keypad
for use with F R E Q . See white secondary switch andknob labels 0 - 9 , decimal point, and enter ( ).
First, hold F R E Q . Then enter one or two MHz digits,
optionally followed by a decimal point and up to three
kHz digits. Next tap. ( B A N D ) to accept, or any
other switch to cancel. Examples:

Characteristics of each amateur band are briefly
summarized below. For further information, see the
ARRL band plan (www.arrl.org/band-plan-1).

14.255 MHz: F R E Q
7.000 MHz: F R E Q

To change bands: Tap B A N D , rotate the VFO A knob
to select the desired band, then tap any switch to exit.
You can also change bands using direct frequency
entry (described at right) and memory recall (pg. 24).
Band
(m)

Range
(MHz)

Best
DX

Other
Characteristics

160

Night

80

1.8-2.0(RX only)
3.5-4.060~5.3-5.4

Night

40

7.0-7.3

Night

30
20

10.1-10.15
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

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:
PSK ~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 QRP DX band; CW beacons(28.2-28.3) show if band is open

Night

Day

1 4 . 2 5 5
7

.

. .

.

Mode Selection
Tap M O D E to select SSB, CW, or AM mode. Tap
D A T A to select data mode (pg. 15). To select alternate
modes (USB/LSB, CW normal/reverse, or DATA
normal/ reverse) use the ALT MD menu entry.
SSB (pg. 20) is either LSB (lower sideband) or USB(upper sideband). LSB is normally used on 160, 80,
and 40 m, while the other bands normally use USB.
CW mode (pg. 21) uses much less bandwidth than
SSB, providing a high signal-to-noise ratio ideal for
low-power (QRP) operation.
AM mode (pg. 22) has a characteristic “warm” tone. It
can be used for listening to broadcast stations.
DATA modes (pg. 27) are often used with a computerconnected to the KX2 to send/receive text. However,there are also three built-in data modes that use the
KX2’s display for received text, and a keyer paddle fortransmit, converting the CW you send into data.
15

VFO A and B

Incremental Tuning (RIT and XIT)The KX2 provides two VFOs (see glossary, pg. 66).
Each VFO has its own frequency, mode, and filter
settings. Use of VFO B ( O F S / B ) is optional.

RIT, or receive incremental tuning, adjusts the receive
frequency without affecting your transmit frequency.
RIT is sometimes called a clarifier since it can be used
to tune in voice signals clearly. It is also useful in CW
and DATA modes when a station calls off-frequency.

VFO A normally controls both the receive andtransmit frequency. If you use VFO A to tune in asignal clearly, you’ll also be on-frequency for transmit.

XIT, or transmit incremental tuning, adjusts thetransmit frequency without affecting the receive
frequency. (An alternative is to use SPLIT, pg. 30.)

VFO B can serve as a holding register for a frequency
of interest (see A / B swap below). It is also used with
S P L I T (pg. 30) and Dual Watch (pg. 25). To tune
VFO B, first make sure the B LED above the knob islit. If not, tap the O F S / B knob.

∆ F (Delta-F) LED : This LED turns on whenever
RIT, XIT, or SPLIT is in use as a reminder that yourreceive and transmit frequencies may be different.

Tuning rates: Tapping R A T E normally alternates
between 10 Hz and coarse-tuning steps (MENU:VFO
CRS). The default coarse step size for CW is 0.1 kHz,and for SSB, 0.5 kHz. In DATA modes, or when theaudio peaking filter is in use in CW mode (APF, pg.
18), R A T E alternates between 1 Hz and 10 Hz steps.

To use RIT: First, tap R I T . This turns on the R I T
icon and the O F S LED. Adust using O F S / B .

is used to tune VFO A in coarse steps.
For this purpose, the O F S LED must be lit (if not, tap
the knob), and RIT (see at right) must be turned off.

To zero the RIT/XIT offset: Hold C L R .

To use XIT: XIT is controlled using MENU:XIT.
Setting the menu entry to O N turns on the X I T icon
and the O F S LED. Adjust using O F S / B .

OFS/BYou can still use theO F S / B control to tune
VFO B, even if RIT or XIT is turned on. Just tap theknob to turn the B LED back on. The RIT/XIT icons
on the LCD will retain their current states.

To lock VFO A: Hold F R E Q for about 3 seconds. Tap
R A T E to unlock. To lock VFO B, first swap it withVFO A, lock A, then swap again.

Special VFO B Displays

To copy VFO A’s frequency to VFO B: Hold
A > B . Tap twice to copy mode and filter settings aswell.

To see special information on VFO B, tap D I S P , thenrotate O F S / B . Available displays include time,
supply voltage, supply current, amp hours used, logged
text review, etc. (see pg. 23).

VFO A and B swap: Tap A / B to exchange VFO
frequencies, modes, and all other settings.
16

Receive Settings

Filter Passband Control

The Receive controls group, which includes theA F / M O N knob and the two switches below it, isused to set up the KX2’s receiver. On the display,
directly above these controls, is the filter passband
graphic. This shows the receiver’s audio passband.

Tapping F I L places the KX2 in F I L A D J mode. In
this mode, theA F / M O N andK Y R / M I C knobs
can be used to adjust the filter passband as described
below. Settings are stored per-mode.
The passband graphic shows an approximation of thewidth and centering of the current filter. The example
below shows a medium-width filter that is centered(not shifted):

AF Gain / Monitor Level Control
The A F / M O N knob normally controls receiver AF
gain. Tapping the knob switches its function to MON(monitor volume level). In CW mode, this turns on thesidetone (also see Spot, pg. 21). In SSB mode, you’llhear your microphone audio (pg. 17).

In general, a narrow passband reduces interference(QRM) and noise (QRN), while a wider passband can
reduce listening fatigue and improve fidelity.

Switch activation tones, if used, have the same
volume level as the CW sidetone (as set in CW modeusing M O N ). Switch tones can be set to off, on, orMorse code characters (MENU:SW TONE).

Using F I L A D J mode:••

Preamp and Attenuator
On successive taps, P R E cycles through preamp on(attenuator off), both off, and attenuator on (preampoff). P R E and A T T N icons are updated accordingly.
Typically the preamp is used on the higher bands orwith low-gain antennas. If interference is heavy, turnthe preamp off, and if necessary, turn the attenuator on.

•••

You can improve sensivitity by using the internal
ATU to resonate the antenna. Tap A T U .

Rotate A F / M O N knob to adjust the filter width.
Tap
A F / M O N to normalize the filter to thestandard per-mode setting. This turns on the two“wings” shown at the left and right ends of thegraphic as shown above.
RotateK Y R / M I C to shift the passband left or
right.
Tap
K Y R / M I C to center the filter withoutchanging the bandwidth.
To exit F I L A D J mode, tap any other switch, key
the transmitter, or rotate VFO A.

Filters in the KX2 are implemented entirely within
the digital signal processor (DSP).

The KX2 will automatically reduce receive gain in
the presence of very strong signals. The overload icon
(R X ) will turn on. Also see MENU:COR LVL.
17

Noise Reduction

CW/DATA Tuning Aid (CWT)

Noise reduction (NR) removes random backgroundnoise (hiss or static). It has a characteristic “hollow”
sound. Higher settings may attenuate weak 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. 21). Signals can always be tuned inby ear, but the KX2 also provides a visual tuning aid(CWT). With CWT on (MENU:CWT), the upper halfof the S-meter changes as shown below.

Holding N R turns on noise reduction and displays its
setting, which can then 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/PSK63

RTTY

CWT

Noise Blanking

CWT

S1 3 5 7 9Noise blanking can eliminate repetitive noise such asthat from power lines, appliances, and vehicle ignition
systems. Use the lowest effective setting.

SWR

2 3

S1 3 5 7 9

RF

50

100

SWR

2 3

RF

50

100

A CW signal appears as a single bar. Tune the signal
until the bar is centered beneath “CWT” as shown.
This single-bar display also applies to PSK-D (pg. 28).

Holding N B (a function of the A F / M O N knob) turns
on the noise blanker. The setting can then be adjusted
using this knob. Tap any switch to exit the setting
display. Hold N B again to turn the blanker off.

In RTTY or radioteletype modes, mark and space tones
appear as bars on either side of the CWT pointer (seeFSK D and AFSK A data modes, pg. 28). With nosignal, you’ll see a “ghosting” effect (above). As youtune in a signal, solid bars will appear on both sides.

Audio Peaking Filter (APF) and Notch Filter
In CW mode, holding A P F - A N turns on a very narrowfilter to improve copy of weak CW signals right at thereceiver’s noise floor. The filter graphic changes asshown below, and VFO tuning is set to 1 Hz.

To optimize CW/data text decode, you may need tofine-tune the VFO position. This is especially true in
PSK-D mode. Use 1 Hz steps ( R A T E ).
Spot and Auto-Spot: Tapping K Y R - S P T / M I C
generates an audible spot tone in CW, PSK-D, and
FSK-D modes. Tune the VFO until the signal pitch
matches the spot tone. If CWT (see above) is turned on
in CW and PSK-D modes, tapping this knob will tunein the signal automatically, if possible (auto-spot).

In SSB and AM modes, A P F - A N turns on auto-notch(AN). Auto-notch can suppress one or more audible
carriers (continuous tones) automatically, while having
little impact on speech signals.
18

Transmit Settings

Transmit Controls and ATU Tuning

The Transmit controls group (to the left of the VFO Aknob) is used to set up the KX2’s transmitter. The
nearby TX LED turns on during transmit.

Tap
A F / M O N to set the transmit monitor volume(speech in voice modes, sidetone in CW mode).
X M I T switches from receive to transmit. However, in
CW modes, MENU:VOX MD is usually set to ON, so
you can simply hit the key or keyer paddle to transmit.
(VOX is always on in PSK-D/FSK-D modes.) In SSB
mode, tapping X M I T is an alternative to using mic PTTor VOX. (See pg. 20 for SSB VOX setup.)This section provides an overview of transmit
controls. Detailed per-mode instructions follow.

Keyer Speed-Spot/Mic Gain and Power Output
In CW mode,
K Y R - S P T / M I C sets the keyer speed(in WPM). Tapping the knob spots a signal (pg. 21). In
SSB mode, this knob sets mic gain. A typical seting is15-25 for use with the Elecraft MH3 microphone.

T U N E is used to transmit a CW signal at the power
level selected by the
P W R control. This is usefulwith external wattmeters and antenna tuners. The
TUN PWR menu entry can be used to override the
PWR control setting and transmit at a lower level.

Holding this knob for ~0.5 seconds selects
PWR(power output control). Power level is shown on the
R F bar graph during transmit. Maximum power output
is typically 10 W on 80-17 m, and 8 W+ on 15-10 m.
A power supply voltage of 12 V or higher isrecommended for SSB use at full power.

A T U starts automatic antenna matching if a KXAT2
internal ATU is installed (pg. 19), or if a KXPA100
amp with KXAT100 ATU is connected (pg. 33).
MENU:ATU MD must be set to A U T O . Matchingtakes an average of 4 seconds, initially. Settings arerecalled on band change, or when you transmit after
moving the VFO a significant distance. The ATU icon
flashes briefly when settings are recalled. In CW mode,
recall is delayed until a pause in keying. Also see
MENU:ATU DATA for selection of ATU data sets.

If a KXPA100 amplifier is connected, power can be
set up to 100 W (see KXPA100 owner’s manual).
The right side of the KX2 may become quite
warm during transmit. If the amplifier temperature is
too high, power will be automatically reduced.

With difficult loads, try tapping A T U a second
time within 5 seconds to search for a lower SWR.

Maximum power output varies with supply
voltage and other factors. If output is lower than
expected, use the special VFO B displays (pg. 23) tocheck supply voltage, current drain, and PA
temperature. The selected parameter will be shown on
VFO B during T U N E . (SWR is shown on VFO A.)

P F n (programmable functions): See pg. 25.
M S G and R E C are used to play and record CW, data,
or digital voice messages (pgs. 22 and 30).

19

VOX Setup

SSB Mode

Several menu entries are used to configure SSB VOX(voice-operated transmit):

Use the steps below to do initial SSB setup:
§

Set

§

Tap M O D E to select SSB (either L S B or U S B ).
To change SSB modes, use MENU:ALT MD.

§

Tap A F / M O N to set the voice monitor level.
Start with 3. High settings may sound distorted.

If MENU:VOX MD is OFF (PTT, or push-to-talkmode), the transmitter must be enabled by tapping
X M I T or by holding the mic’s PTT button. With VOXon, the V O X icon turns on, and transmit starts by
speaking. If VOX is on, the remaining menu entries
below should also be set up.

§

Set MENU:TX CMP (speech compression) to 0
initially. Exit the menu.

VOX cannot be used with the built-in
microphone. Use the X M I T switch to transmit.

§

Tap X M I T or hold in the mic’s PTT switch. Note:
Hand-held mics like the Elecraft MH3 should
nearly touch your mouth when you are speaking.

MENU:VOX GN (VOX gain) should be set to trigger
at normal speech level, but not in response toincidental noise. Start with low settings (10-20).

§

While speaking into the mic, adjust mic gain
( M I C ). This will turn on the transmit C M P and
A L C bar graphs. While speaking, adjust mic gain
for about 5 ALC bars (see below). Mic gain for
the Elecraft MH3 is typically set to 15-25, and30-40 for the internal mic.

MENU:VOX DLY sets the VOX (voice-operated
transmit) delay time in seconds. A setting of about 0.5
seconds will keep the radio in transmit mode during
typical continuous speech.

P W R to 0.0 W.

MENU:VOX INH (VOX inhibit, or anti-vox) can
prevent speaker audio from triggering VOX.

Transmit Metering§

To use speech compression, set MENU:TX CMP
to 10-20 initially. Compression increases average“talk power” with only slightly decreased fidelity.

§

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

In SSB mode, tapping
M I C switches the transmit
bar graph from S W R / R F to C M P / A L C .
The C M P / A L C scale is selected automatically when
you adjust mic gain or speech compression. The
S W R / R F scale is restored after a few seconds.

20

CW Mode

Off-Air Code Practice

Basic CW-Mode Setup

Sending CW normally produces both a sidetone and atransmitted signal. If PTT-CW is selected (by setting
MENU:VOX MD to O F F ), hitting the key without
first tapping X M I T will generate only a sidetone. Thisis useful for code practice or keyer speed adjustment.

§
§

§
§
§

Tap M O D E to select C W (normal CW mode).
Some operators prefer to use CW reverse (C W
R E V ). See MENU:ALT MD for details.
MENU:VOX MD can be set to ON (VOX) or OFF(PTT) for CW mode. Most operators use VOX,
allowing the transmitter to be keyed immediately
whenever a hand key or keyer paddle is used. PTT
requires manual transmit start/stop using X M I T .
Set sidetone pitch using MENU:PITCH. 500-700
Hz is typically used with headphones.
Set sidetone volume using M O N .
MENU:VOX DLY sets the break-in or QSK delay(the time before the receiver recovers after keyup). A setting of 0.00 provides full break-in, also
known as “full QSK.” (The QSK icon will appear.)
MENU:CW WGHT provides two variations on
QSK; CW operators may wish to try both.

CW-Mode Menu Settings
You can use the menu to change the settings for iambic
keying (CW IAMB), keying weight (CW WGHT), andpaddle normal/reverse or hand key (CW KEY1 for the
KEY jack, and CW KEY2 for an attached KXPD2 or
KXPD3 keyer paddle).

CWT, SPOT and Auto-Spot
When calling a station, you should try to match yourfrequency to theirs. To facilitate this, the KX2 provides
both a visual tuning aid (CWT), as well as manual andautomatic spotting in CW and some data modes. See
pg. 18.

CW Receive Filtering

CW Text Decode/Display

As conditions change, you can adjust the filter
passband using F I L as described on pg. 17. A narrowpassband can improve copy in the presence of noise orinterference, while a wider passband can be lessfatiguing to listen to. You’ll also find the audio
peaking filter (A P F , pg. 18) to be very useful withweak CW signals.

The KX2 can decode transmitted and received CW
signals, displaying the text on VFO B (pg. 29). This isespecially useful when you’re learning CW, or if
someone who doesn’t know CW is looking over yourshoulder while you make CW QSOs. It’s also
indispensable for CW-to-DATA operation (pg. 27).
The KX2 can also capture transmitted CW for logging
purposes. See MENU:LOGGING.
21

CW/DATA Message Record/PlayAM ModeThere are 3 text messages, each having up to 250
characters. These apply to CW as well as DATA
modes FSK D and PSK D.

To select AM, tap the M O D E switch.

Messages can only be recorded using the KX2’s
built-in keyer function (using either an external keyer
paddle, KXPD2, or KXPD3). An external keyer cannot
be used. Messages can also be viewed or edited using
the KX2 Utility computer application.

AM Receive: AM mode can provide a “warmer”
sound that SSB mode when used to copy shortwave
broadcast stations. Also, VFO tuning is less critical.
MENU:VFO CRS provides coarse-tuning selectionsof 1, 5, 9 and 10 kHz for AM mode.

Message Record: To start recording, hold R E C , thenselect a message by tapping any of switches 1 through3 of the numeric keypad (the P R E , F I L , and A T U
switches, respectively). The remaining text space will
be displayed as you send. Tap MSG to finish
recording.

A good place to look for AM amateur signals is around3.870 MHz at night.

To disable AM mode, use MENU:AM MODE.

AM Transmit: Setup for AM transmit is the same as
for SSB (pg 20). However, speech compression shouldin general be turned off for AM mode (MENU:TX
CMP). The RF bar graph will indicate about 1/3 to 1/2
the power set by the power control.

Message Play: To play, tap M S G , then select amessage (1 through 3). To cancel, tap X M I T or hit the
keyer paddle or hand key.

AM is far less power-efficient than SSB, so at QRPlevels, SSB is preferred for most communication
purposes.

Message Erase: Hold R E C , select a message (1through 3), then hold C L R .
Auto-Repeat: To auto-repeat a message, tap M S G ,but then hold rather than tap a message switch (1through 3). MENU:MSG RPT sets the message
repeat interval (1 to 255 seconds). To cancel autorepeat, tap X M I T or hit the keyer paddle or hand key.
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.
22

Advanced Operating Features§

Audio Signal level (AFV). Shows the KX2’saudio output level, prior to the AF gain control(the AF gain control has no effect on this reading).
The reading will vary with preamp and attenuatorsettings. AFV is used along with dBV (below).

§

Relative audio signal (dBV). Used to measure
receiver sensitivity or or to compare signals. First
select AFV (described above) and allow thevoltage reading to stabilize. (This may not be
possible with rapidly changing signals.) Once thesignal appears stable, select dBV. You should now
see a reading of around 0 dBV (see Glossary)
relative to the last AFV reading. If you change thesetting of the preamp or attenuator, you should see
this reading change. However, it may not change
as much as you expect unless you also turn AGC
off using the AGC menu entry. (Be sure to turnAF gain down before turning AGC off, as thesignal may become very loud.)§Amp hours: Shows total amp hours used since
the value was last reset (for details, see
MENU:AMP HRS). Used to test batteries or
estimate remaining battery charge.

Special VFO B Displays
The KX2 can display time of day and other parameterson the VFO B display. To access these displays, tap
D I S P , then rotate theO F S / B control.
The following special displays are available:§

24-hour time, obtained from the real-time-clockon the KXIO2 option module. If a KXIO2 is notinstalled, the time since last power-on will be
displayed. Set the time using MENU:TIME.

§

Power supply voltage. If you have both aninternal battery and an external power source
connected to the KX2, the display will show thehigher of the two voltages. This display, as well as
the next two, stay visible even when using T U N E ,so you can check key-down conditions.

§

Supply current. Typical receive-mode current is0.15-0.20 A. It can be reduced by turning off the
LCD backlight and preamp, and by using
headphones. Transmit current is typically 1 to 3 A.

§

Power Amplifier (PA) temperature. The KX2’s
internal PA temperature is shown as P A . I n n C(Internal). If a KXPA100 is connected via theremote-control cable, MENU:PA MODE is O N ,and P W R is set to > 10 W, the KXPA100’s PA
temperature is shown, as P A . X n n C (eXternal).
PA temperatures rise gradually as you transmit.

Hold C L R while in the AMP HRS menu
entry to zero the amp hours value.
§

Log Data: Use VFO A to scroll through recorded
outgoing CW/DATA text. Also shows time stamps
and band/mode. See MENU:LOGGING.
Hold C L R to erase all log data.

23

Frequency Memories

Scanning

The KX2 has 100 general-purpose frequency memories(00-99), plus four quick memories on each band. Eachmemory stores VFOs, modes, and other settings. Quickmemories provide an easy way to get to segments 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. Memories can be set up manuallyor with the Elecraft Frequency Memory Editor (pg. 35).

Scanning tunes a band segment continuously until amodulated signal is found. To use scanning:§§

To store a general-purpose memory (00-99): First
hold S T O R E , then locate the desired memory byrotating the VFO A knob. The VFO A frequencies
presently stored in each memory will be shown. Whenyou reach the desired memory number, hold S T O R E
again to exit, or tap any other switch to cancel.

§

Set VFO A and B to the desired scan start/end
frequencies, and VFO A to the desired mode.
S T O R E in memory 00-99 as described at left.
To start scanning, first recall a general-purpose
frequency memory as described at left. Then holdR C L / S C N until S C A N appears on VFO B (~3 s).
To stop scanning, rotate VFO A or tap any switch.
To restart, hold R C L / S C N for about 3 seconds.

Channel Hopping
Scanning (or manually tuning) among a group ofmemories is referred to as channel hopping. This isespecially useful on 60 m. Memories in a group mustall be in the same band, but can have different modes.

To recall a general-purpose memory: HoldR C L / S C N , then select a memory using VFO A. Tap
any switch to exit.

To set up channel hopping:

To store a per-band quick memory: Hold S T O R E ,then tap the target quick memory (1 - 4).

§

To recall a per-band quick memory: HoldR C L / S C N , then tap the target quick memory (1 - 4).

§

To erase a general-purpose memory: While scrollingthrough memories to store or recall, hold C L R .

§To add a text label to a general-purpose memory:First hold R C L / S C N , then select a memory (00-99)
using VFO A. Next, rotate VFO B to select each text
label position in turn as indicated by the flashingcursor. Use VFO A to select label characters (A-Z, 0-9,
and symbols). Hold S T O R E to exit.

§

§
24

Set up VFO A for the first target frequency andmode. S T O R E this setup in a memory (00-99).
Set up and S T O R E 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, recall one of thememories in the target group. VFO A will now hop
among the grouped memories. Holding R C L / S C N
for ~3 seconds starts scanning within the group.
To disable channel hopping, tap R A T E .

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 access it via P F n (described below).

Audio Effects
Stereo headphones or dual external speakers can beused with the KX2’s DSP audio effects (AFX). At
present the KX2 provides one audio effects mode,
D E L A Y , which creates an illusion of acoustic “space,”
resulting in a less-fatiguing sound and in some cases
better copy of weak signals. MENU:AFX MD is used
to select the desired AFX setting.

Dual Watch Limitations:§

Dual Watch
Dual watch allows you to listen on both the VFO A
and VFO B frequencies, as if you had two receivers.
You’ll hear the signal at VFO A in the left channel,
and the signal at VFO B on the right.

§§

Stereo headphones or dual external speakers
are required to use dual watch.

VFO B can be up to 7 kHz above VFO A, or up to
23 kHz below VFO A. If you exceed thisseparation with DUAL RX turned on, the S U B
icon flashes slowly as a reminder. This doesn’t
prevent you from exceeding the separation, but it
does disable dual watch until the VFOs are back inrange.
Dual watch overrides the normal audio effects
mode (AFX MD).
Headphones or external speakers must be used.

Programmable Function Switch (PFn)You can access up to four often-used menu entries
quickly by assigning them to programmable functions
PF1-PF4. This is done using the P F n switch.

Dual watch has various uses. For example, you might
be waiting for a station on VFO B’s frequency tocomplete a QSO, while using VFO A to look for otherstations. You can tap A / B to alternate between thetwo frequencies.

To set up a programmable function:§

Dual watch is also ideal for working DX stations thatare listening at an offset from their transmit frequency.
You can listen to the DX station on VFO B, while
using VFO A to find the station they’re presently
working. Once that station has been found, you may
want to move up or down slightly to find a clear spot in
which to call.

§§

Hold M E N U , then rotate VFO B to find the target
menu entry.
Hold P F n , then tap 1 through 4 to assign PF1PF4 to this menu entry. You’ll see P F n S E T .
Exit the menu.

If a parameter has only two values, accessing itwith P F n will change the value and exit the menu.

25

Receive Audio Equalization (RX EQ)Transmit Audio Equalization (TX EQ)

The KX2 provides 8 bands of receive audio
equalization via the RX EQ menu entry. RX EQ cancompensate for physical acoustics (of the room,
headphones, internal speaker, external speaker),
tailoring the audio to your personal preference.

Most microphones, including the Elecraft MH3
and the KX2’s built-in mic, will provide good audio
quality with default (flat) TX EQ. Also, excessively
high TX EQ settings can cause distortion.
If required, transmit audio equalization can compensate
for microphone and voice variations. MENU:TX EQ
works exactly the same as RX EQ (described at left)
and can be adjusted during transmit. TX EQ is notapplicable to CW or DATA modes.

Two receive EQ setups are provided: one for CW
mode, and the other for SSB mode. RX EQ does not
apply to DATA modes.
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.

While adjusting TX EQ, monitor your voice using
headphones (use MON to set the level), or listen to
your transmitted signal on another receiver. If you hear
distortion, reset all TX EQ bands using C L R . You may
also have excessive mic gain or compression.

USB
A
VOX
AGC-S

ANT 2
ATU
PRE

NB

XFIL

RIT

TX

SSB/CW VFO Offset

B

FL2

The KX2 can automatically offset the VFO frequency
when you switch from SSB to CW mode, so otherstations will hear the correct CW pitch. See
MENU:CW WGHT for details.

The center frequencies of the 8 audio EQ bands are 50,
100, 200, 400, 800, 1600, 2400, and 3200 Hz. To selecta band to change, tap 0 - 7 on the keypad. For example,
tapping 0 selects the 50-Hz band.
Next, rotate VFO A to specify boost or cut (+/- 16 dB).
The illustration above shows the 800 Hz EQ band
(0.80 kHz) being set to +1 dB of boost. You can holdC L R to reset all of the RX EQ bands to 0 dB (no cut or
boost).

26

You’ll now be able to copy RTTY signals. If you see
only numbers and punctuation, try tapping DATA
twice to restore “letters” mode.

Data Modes
The KX2 supports data operation via a computer andspecial software. But it can also be used in RTTY andPSK31/PSK63 modes without a computer, thanks tothe built-in FSK D and PSK D modes.

RTTY stations can most often be found on 20 m, from
14080-14090 kHz. Other popular “watering holes”
include 80 m (3570-3600), 40 m (~7040 and ~7080),
17 m (~18100), and 15 m (~21080). During contests,
stations spread out over a much wider range.

5.0 watts or lower is recommended in all data
modes. The KX2 will reduce power, if necessary, tomaintain a safe operating temperature.

To transmit in FSK D mode (CW-to-Data): Plug akeyer paddle into the KEY jack, or attach a KXPD2 (orKXPD3) paddle at the front of the KX2. (See the CW
KEY1 and CW KEY2 menu entries.) When you send
CW, the KX2 will convert it to RTTY. (You’ll hear the
CW sidetone as well as weak RTTY tones.)

Mic gain, RX/TX EQ, and TX CMP are notapplicable to FSK D and PSK D modes.

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

Tap D A T A to select data modes.

§

Tap D A T A again and rotate O F S / B to selectthe FSK D sub-mode. Tap the switch again to exit
the sub-mode display. A dual-passband(mark/space) filter will appear:§

Hold T E X T to turn on text decode.

§

The sideband can be reversed (MENU:ALT MD).

§

Optionally turn on the tuning aid (CWT, pg. 21).

You can use CW message memories in FSK D mode,
as well as with KX2 Utility’s Terminal function (pg.
35). FSK-D mode transmit text can also be captured
for logging purposes (see MENU:LOGGING).
You cannot use a hand key for FSK D transmit.
The KX2 adds a 4-second “idle time” (giving you
time to decide what to say next) each time you stop
sending. At the end of this period, the receiver is reenabled. To terminate the idle period quickly, send
the character . . - - in CW. This “IM” prosign canalso be inserted at the end of a message. It will not betransmitted on the air, but you’ll hear it in your CW
sidetone.

1

are encoded using a 5-level code called baudot, at a baudrate of 45 baud, or about 60 words per minute.

FSK stands for frequency-shift keying, used with RTTY
(radioteletype). The KX2 uses a 170 Hz shift. RTTY signals

27

PSK D Mode (PSK31/PSK63)

Audio Data Modes (DATA A and AFSK A)PSK D is the KX2’s built-in version of PSK31 (orPSK63)2, which is highly reliable at low power levels.

A computer, sound card, and appropriate software canbe used with the KX2 for data communications. Manydifferent modes can be used in this way, including
PSK31/63, RTTY, JT65, Pactor, Olivia, MFSK, SSTV,
etc. The KX2 provides DATA A mode for thispurpose. DATA A automatically disables compression
and RX/TX EQ. Upper sideband is the default.

To use PSK D mode:§Tap D A T A to select data modes.

§

Tap D A T A again and rotate O F S / B to selectthe PSK D sub-mode. Use VFO A to select 31 or
63 baud. Tap D A T A again to exit. A narrowreceive passband will be selected.

§

Hold T E X T to turn on text decode. (Also see
MENU:LOGGING for PSK-D text capture.)§

The sideband can be reversed (MENU:ALT MD).

§

Optionally turn on the tuning aid (CWT, pg. 21).

For audio-based RTTY, you can also use AFSK A
mode. Like FSK D, AFSK A provides a dual-passband
RTTY filter and text decode. The VFO is tuned to themark frequency. Lower sideband is the default.
To use audio data modes:§

Before attempting to transmit in this mode, you should
practice tuning in signals. Try listening to 1407014073 kHz (20 m), tuning signals in 1 Hz steps until
the decode appears accurate.

§§

A PSK signal can sometimes be tuned in at
multiple VFO frequencies, separated by ~8-16 Hz. To
ensure you’re listening on the correct frequency before
you transmit, use auto-spot (pg. 21).

§

For PSK D transmit, a keyer paddle directly conntectedto the KX2 is required. Use the “IM” prosign toterminate transmit quickly. (See previous page.)§2

PSK stands for phase-shift keying. 31 and 63 refer to thebaud rates, 31.25 or 62.5 baud. PSK signals are encodedusing a very efficient representation called varicode.

28

Tap D A T A twice; rotate O F S / B to selectD A T A A or A F S K A . Tap D A T A to exit.
In A F S K A mode, optionally hold T E X T to turnon text decode. Also see CWT (pg. 21).
Connect your computer’s line-audio output to the
MIC jack. Connect the KX2’s PHONES jack toyour computer’s line-audio input. Shielded cables
should be used. You may need an attenuator if thedrive levels are too high.
Refer to your data communications software
manual to determine how to set up the KX2’s VFO
for accurate frequency display.
VOX can be used for data; see MENU:VOX MD.

§
§

§

While transmitting audio data, adjust MIC gain for
no more than 4 to 5 bars of ALC indication.
RX/TX EQ and TX CMP are not applicable to
DATA A and AFSK A modes.

§§

Text Decode And Display
The KX2 can decode CW, PSK31 or PSK63 (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.
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 CWT as a tuningaid (pg. 21). Also, auto-spot (pg. 21) can be used toautomatically tune in signals.
Hold T E X T . In DATA modes, this will alternate
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 / B to select a text decode mode. T X
O N L Y displays only CW characters you sendusing the internal keyer. To decode text from onair CW signals, use one of the R X T H R nsettings. Turn CWT on and adjust the threshold sothat the CWT bar graph segment flashes in timewith the incoming CW. Use higher R X T H R nsettings for stronger signals as well as faster CW
speeds.
29

In CW, PSK-D and FSK-D modes, transmitted text
can be captured (see MENU:LOGGING).
Use a filter bandwidth of 0 . 3 0 kHz or less.
For further details on data modes, see pg. 27.

Split Operation

allows you to transmit as much as to 23 kHz up. To dothis, simply turn split OFF (VFO A will then be the TX
VFO), and listen to the DX station with VFO B (using
dual watch). This is actually easier than normal split
operation, because VFO A has a larger tuning knob.

Often you’ll hear a DX station being called by manystations, creating a pileup. To ensure that he has a clear
transmit channel, the DX station may say “UP” or“DOWN” periodically to indicate that he’s listening
above or below his transmit frequency. For example, in
CW mode he might transmit on 14025 kHz, but listenin the vicinity of 14027 kHz. In this case he would
periodically send “UP 2” (or just “UP”) as a reminderof where to call him. SSB pileup-split operation issimilar but may occur over a much wider range.

Digital Voice Recorder (DVR)
You can record two SSB-mode transmit voicemessages of up to 15 s each, such as your call sign or a
CQ, and play them back one time or with auto-repeat.
This can save your voice, especially in an SSB contest.
For example, you could record your callsign in one
message and a fixed exchange in the other.

To use split, first hold A > B twice to set VFO B to thesame mode, frequency, and filter settings as VFO A.
Then tune VFO B up about 2 kHz (or the desired
offset). Finally, hold S P L I T . The S P L I T icon will turnon, and the T X icon will point at VFO B, since VFO B
is now controlling your transmit frequency.

The transmit voice monitor should be used so
you can hear DVR playback. This can be adjusted inreceive mode. First, tap
A F / M O N to select themonitor level function. Then, while speaking into themic, use this knob to adjust the level. Start with 5.

Using dual watch with and without SPLIT

DVR Record:

DX stations will tune in the vicinity of their specified
listening frequency when searching for callers. Finding
a clear spot in which to transmit will improve yourchance of being heard. This is where dual watch comesin. With dual watch ON, you can listen to your RX and
TX frequencies at the same time (pg. 25). You’ll beable to tune VFO B to find a clear spot, while still
listening to the DX station at VFO A’s frequency. VFO
B can be set up to 7 kHz above or 23 kHz below VFO
A. Outside this range, dual watch is disabled, and theS U B icon flashes as a reminder.

Hold R E C , then tap 1 or 2 on the numeric keypad. The
current message will be erased (4 s). When prompted,
tap X M I T and start speaking into the mic (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.
DVR Play:
Tap M S G , then tap 1 or 2. To cancel, tap X M I T or hit
the key. To auto-repeat a message, tap M S G , but thenhold rather than tap 1 or 2. MENU:MSG RPT sets
the repeat interval (1 to 255 seconds).

If an SSB-mode pileup extends more than 7 kHz above
the DX station, you can use a different technique that30

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

Cross-Mode Operation
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 SPLIT. When you
transmit, the SSB station will hear your CW signal at
the pitch of your sideone. Use a fairly slow CW speed,e.g. 15 WPM, if you’re not sure of the SSB operator’scode proficiency level.
You can also send CW in SSB mode without using
split, if the CW-in-SSB feature is enabled. See
MENU:CW WGHT for details.

Custom Power-On BannerYour KX2 can display a customized text “banner” onpower-up, such as your name and callsign. The banner
scrolls across the VFO B display.
To set up a banner, use the Configuration screen of the
KX2 Utility application.

31

Logging (CW/Data Modes)

Transverter Bands

When using the KX2 hand-held, or if operating time isvery limited, logging may be inconvenient. The KX2
can capture up to 2048 transmitted characters, alongwith time, band, and mode data, so you can update apaper or electronic log later on. Log data can bereviewed at the KX2 itself using the DISP/LOG
function, or by sending the data to KX2 Utility.

Seven user-definable band displays are provided foruse with external transverters, such as the Elecraft XVSeries.
The KX2 does not have a low-level transverter
output; transverters are driven from the main
antenna jack. This requires the use of transverters thathave a common receive/transmit antenna jack andassociated T/R switching. Consult the transverter
manual for drive power limitations and switchingrequirements.

Logging applies only to CW (C), PSK-D (P) and FSKD (F) modes, and requires use of the internal keyer,
either with a separate or attached paddle.
For complete instructions see MENU:LOGGING.

The KX2’s ACC jack provides a keyline output thatcan be used to key transverters. See pg. 9.

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

32

Locate the XVn ON menu entry. Tap 1 – 7 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 (7, 14, 21, 28, or 50
MHz). Most transverters use a 28 MHz I.F.
XVn PWR sets maximum KX2 power output forthe current transverter band in watts.
XVn OFS can compensate for a frequency offset
in the transverter.

KXAT2 wide-range internal automatic antenna
tuner (ATU): With a KXAT2 installed, you can use
non-resonant and narrow-band antennas. An ATU can
improve transmit power output and receive sensitivity.
The ATU provides two sets of tuning data for use athome and field locations (see MENU:ATU DATA).

Options and Accessories
This section describes all available KX2 options andaccessories. Option modules are easily user-installable,
in any order, without soldering.
AX1 whip: This 4 foot (1.2 m) telescoping whip
covers 20 and 17 m, and is ideal for pedestrian mobile(hand-held) and general field use. It breaks into two 6”(15 cm) pieces so it will fit into a pocket or our CS40
bag. Options include the AXE1 40 m extender.

KXPA100 100-watt amplifier: The KXPA100 is arugged 100 W, 160-6 m linear amplifier that can beused with the KX2, KX3, or any other QRP
transceivesr. An internal 100 W ATU is also available
for the amplifier (KXAT100). The KX2 can remotely
tune the 100 W ATU (pg. 19) and control its antenna
switch (MENU:ANT.X SW). If a KXAT100 isavailable, the the KX2’s internal ATU (KXAT2) will
be placed into bypass mode automatically.

MH3 hand mic: The MH3 microphone includes ahigh-quality element, space-saving right-angle plug,
PTT switch, and VFO UP/DN function buttons.
KXPD2 keyer paddle: The KXPD2 is a very compact
mechanical keyer paddle that attaches directly to thefront of KX2 (or KX3). This eliminates the need for aheavy keyer base. It includes a slot in which to store
the contact-adjustment allen wrench.

A KX2 Accessory Cable (KX2ACBL) is required
to split the KX2’s ACC jack into two jacks: KEY OUT(2.5 mm) and serial I/O (3.5 mm). The KXPA100
comes with cables that plug into these two jacks.
CS40 and CS60 carrying cases: These are highquality, padded carrying cases with an internal
zippered compartment. The CS40 is extremelycompact, with space for the KX2, AX1 whip, antennawire, an earbud-style headset, a few adapters, and asmall paper log. The larger CS60 has space for an
MH3 microphone and additional items.

A KXPD3 keyer paddle can also be used with
the KX2, though a modification may be required.
Contact Elecraft for KXPD3 modification instructions.
KXIO2 real-time clock module with 2 generalpurpose outputs: The KXIO2 option provides a realtime clock and two user-programmable outputs (AUX
jack). The time can be displayed in the KX2’s VFO B
area (see pg. 23 and the TIME menu entry). Also see
MENU:LOGGING. The two AUX outputs can be used
for controlling external equipment such as an antenna
switch (see the AUX 1 and AUX 2 menu entries).

KX2GNDPLUG: This mini-banana plug can be used
to make a quick-disconnect ground wire (pg. 10).
BNC-BP: BNC to binding-post adapter for secureattachment of wire antennas to the KX2 (pg. 10).
33

Checking your Firmware Revision

Firmware Upgrades

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.

New features and improvements are available to all
KX2 owners via free firmware upgrades. Upgrades
may also be required when you install option modules.
Please visit the Elecraft KX2 software page(www.elecraft.com/KX2/KX2_software.htm) to obtainour free firmware download application, KX2 Utility.
This program runs on PCs, Macs, and Linux platforms.
In addition to firmware downloading, KX2 Utility
provides automated TX gain calibration, a custom
power-on banner, configuration save/restore,
CW/DATA message editing, and a CW/DATA
terminal function.

KX2 Firmware Self-Test
If the KX2 detects an error in its firmware (an incorrect
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 KX2 to your computer, thenrun KX2 Utility, which will reload the firmware. Whilefirmware is loading, the Delta-F LED (∆ f ) will flash.
When the download is complete, the KX2 should reset
and run normally.

Connecting the KX2 to a Computer
The KX2 is supplied with cable for connection to acomputer. The standard cable is model KXUSB, foruse with a USB port. Cable model KXSER is available
for use with an RS232 port.

Forcing a Firmware Download
If you accidentally load an old or incompatible
firmware version and find the KX2 unresponsive, do
the following: (1) Unplug the KX2 from the power
supply. If an internal battery pack is installed,
disconnect and remove it. (2) Plug a power supply in(or reinstall the removed battery). (3) hold the KX2’s
R A T E and A / B switches simultaneously 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 KX2 to a computer and run KX2 Utility, which will
load new firmware.

At the KX2 end, connect this cable to the 3.5 mm ACC
jack. (ACC cable pinout is shown on pg. 9 forreference.)
Within KX2 Utility, select the new USB or RS232
com port associated with the KX2’s serial cable.
Some applications or peripheral devices may
interfere with KX2 downloads; check the Help
information in KX2 Utility if you have difficulty.

34

Automatic Antenna Control

Remote Control of the KX2Some antenna control units (e.g., those used with
SteppIR™ antennas) can track the KX2’s band andfrequency by watching for “IF;” (rig information)
packets from the transceiver’s serial port (ACC jack).
To configure the KX2 to send these packets, set
MENU:AUTOINF to A N T C T R L . The packets aresent once per second while the VFO frequency is beingchanged, as well as on band or mode change.

Computer Control and Logging
With appropriate software, any computer with an
RS232 or USB port can be used to control the KX2.
See Connecting the KX2 to a Computer (pg. 34).
Third-party logging and contesting software isavailable for various computers and operating systems.
Select KX2 as the target radio when available. If not,select another Elecraft transceiver.

CW/DATA Terminal Applications

For a list of compatible software applications,
including configuration requirements, please visit

The KX2 can handle CW/PSK/RTTY ASCII texttransmit and receive via its ACC port (RS232 or USB).
Our KX2 Utility application includes a Terminal
function that lets you use these modes with yourcomputer’s keyboard and monitor. At the KX2, selectFSK-D data submode for RTTY, PSK-D for PSK31 or
PSK63, or CW. Then follow the Help instructions
within KX2 Utility.

http://www.elecraft.com/k2_remote.htm

Remote-Control Commands
The KX2 has a rich set of remote-control commands.
These commands use ordinary ASCII characters, sothey can be easily tested using a terminal emulator or
the Command Tester screen in KX2 Utility. For
example, the command “FA;” returns the current VFO
A frequency. Using the same command, you can set
the frequency, e.g. “FA00007040000;” sets the VFO to
7.040 MHz. The “LG;” command lists the contents of
the KX2’s built-in transmit log (MENU:LOGGING).

Elecraft Frequency Memory Editor
The KX2’s frequency memories (pg. 24) can be easily
viewed and changed using our Elecraft Frequency
Memory Editor. This program shows the contents of
all 100 regular memories, as well as per-band quickmemories, in a spreadsheet format. You can also set
VFO A directly to a memory from within the program.

Many specialized commands are provided in addition
to the core set of commands supported by the K3S/K3.
Please refer to the K3S/K3/KX3/KX2 Programmer’s
Reference for further details.
35

Configuration

Menu Settings

Option Module Enables

The menu entries described in this section are often
used to tailor the KX2 to the operator’s requirements.
You may also wish to review the full list of menu
entries, starting on pg. 41.

Whenever an option is installed, use the associatedmenu entry to set it up (see Menu Functions, pg. 41).
When installing internal options, open the KX2
enclosure using the procedure on pg. 6.
§

§

§

§

Auto Power-Off

KXAT2 Antenna Tuner (ATU): Set ATU MD to
A U T O . Exit the menu and turn the KX2 off, thenback on. See pg. 10 for recommended antennas andpg. 19 for ATU controls.
KXPD2 (or 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. (The KEY jackon the left side panel is configured using the CW
KEY1 menu entry. The keying device plugged into
KEY is independent of the KXPD2 or KXPD3.)
KXIO2 Extended I/O Option (with RTC): Set
KXIO2 menu entry to N O R . Exit the menu andturn the KX2 off, then back on. Set time using the
TIME menu entry. See the AUX 1 and AUX 2
menu entries to configure the AUX outputs.
KXPA100 External 100-W amplifier: See
PA MODE menu entry and KXPA100 manual.

The KX2 can turn itself off after a specified period ofinactivity (i.e., no use of the controls). Use the
AUTOOFF menu entry to select the time period inminutes. The default is I N F I N I T E .

Low-Battery Warning
You can set BAT MIN to warn you when an internal orexternal battery is approaching end of charge. B A T
L O W is displayed periodically when this level isreached. The default voltage (1 0 . 0 V) is appropriate
for many 12 V batteries, as well as the specified
internal 11 V battery.
The KX2 will turn itself off when the supply
voltage drops below about 7.5 volts, regardless of the
BAT MIN setting.

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. Mode B may be preferred byoperators who do “squeeze” keying. Both modes

After changing option enables, use KX2 Utility
to save your configuration. The configuration canthen be restored later if later required.
36

provide dot- and dash-memories—enabling fast code
speeds—but with slightly different timing.

The clock circuitry must be powered by either the
KX2’s internal battery or an external supply. Refer tothe KXIO2 menu entry for details.

Microphone Settings

VFO Coarse Tuning Steps

If you plan to use voice modes, set up MIC BIAS and
MIC BTN to match your microphone.

VFO CRS can be used to set up a coarse tuning
increment for each mode. Tap R A T E to select normal
or coarse tuning.

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 tones at various speeds (C O D E
n n ). Switch tones use the CW sidetone volume level,
which can be adjusted in CW mode using theA F / M O N control.

TUNE Power Level

Setting the TimeIf you have the KXAT2 internal ATU installed,power is automatically set to 3.0 watts during antennatuning. There’s no need to configure TUN PWR inthis case.

If you’re using an external antenna tuner or amplifier
with the KX2, you may want to limit the power level
used during T U N E . The TUN PWR menu entry can beused to set the desired power level.

MENU:TIME sets the 24-hour real-time-clock (RTC)
if a KXIO2 module is installed and MENU:KXIO2 is
set to N O R . If no KXIO2 is installed, time will start at
0 0 : 0 0 : 0 0 at power-up, though you might still want to
set it for time-stamping CW/DATA log text (seeMENU:LOGGING).

VOX (Voice Operated Transmit) Setup
If you plan to use VOX in SSB or data modes, you’ll
need to set up the VOX GN and VOX INH (anti-VOX)
menu entries. See pg. 20.

While in the menu entry, tap 1 / 2 / 3 to selectH H /M M /S S (hours/minutes/seconds), respectively.
Then use VFO A to adjust the value. KX2 Utility canalso be used to accurately set the time.

After changing menu settings, use KX2 Utility tosave your present configuration. The configuration
can be restored later if required.

To display the present time, tap D I S P and rotate
O F S / B to locate the time display.
If the clock appears to be off by more than +/- 2
seconds per day, use the RTC ADJ menu entry toapply a correction.
37

Calibration
All calibration steps are performed at thefactory. If you wish to re-do any calibration steps,
be sure you have the test equipment specified.
To view the tech-mode menu entries used forcalibration: Hold M E N U , then use
O F S / B tolocate the TECH MD menu entry. Change theparameter to O N . Then exit the menu.
To unlock the parameter for any tech-mode menu
entry: Hold F R E Q until you see the lock symbol( ) turn off (about 3 seconds).

§

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

§Tap F I L , then tap A F / M O N to normalize thefilter passband (0.40 kHz). Tap F I L again to exit
F I L A D J mode.

§

Hold M E N U , then rotate
O F S / B to locate the
REF CAL menu entry. Hold F R E Q for about 3
seconds to unlock the parameter.

§

Write down the current 8-digit parameter value:_________________ .

§Tap
K Y R - S P T to auto-spot the signal. The
REF CAL parameter value should automaticallymove up or down a small amount. When it stops
moving, the bar directly beneath the CWT icon
should be turned on as shown below. You can also
adjust the frequency manually using VFO A.

Reference Frequency
Using the calibration procedure below, you canachieve accuracy of better than +/- 10 Hz. This
procedure requires a stable signal generator, or an onair 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.
§

Select CW mode by tapping M O D E .

§Hold M E N U . Rotate
O F S / B to find DUAL
RX. Set it to O F F . Next, locate MENU:CWT and
set it to O N . Then exit the menu.

§

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

§

CWT
S1 3 5 7 9

SWR

P W R toUse direct frequency entry (pg. 15) to set VFO A
to the exact frequency of your signal generator oron-air signal source.
38

2 3

RF

50

100

§

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.

§

Write down the new 8-digit parameter value:________________ .

§Exit the menu by tapping D I S P .

§Save your configuration using KX2 Utility.

Receive Opposite Sideband

Transmit Gain

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

This procedure compensates for per-band transmit gain
variations. An 11-14 V power supply or battery is
required, as well as a 6-W (or higher) dummy load.

This procedure is normally done only at thefactory. Instructions available on request.

Automated Transmit Gain Calibration
To use automated gain calibration (recommended),connect the KX2 to a computer, run KX2 Utility, andselect the Calibration tab. Click on Calibrate
Transmitter Gain. Follow the on-screen instructions.

Transmit Bias
This automated procedure sets the transmit bias currentof the 10 W amplifier stage to ensure low distortion.

Manual Transmit Gain Calibration§

Make sure nothing is connected to the KX2’s
antenna jack.

§Hold M E N U , then rotate
O F S / B to locate the
TX BIAS menu entry. Hold F R E Q for about 3
seconds to unlock the two parameters. Note: These
parameters cannot be manually adjusted.

§§§

Use direct frequency entry (pg. 15) to set the
KX2’s operating frequency to 3.7 MHz (80 m).

§

If you have the KXAT2 ATU option installed, put
it into bypass mode using MENU:ATU MD. Set
the TUN PWR menu entry to N O R . Exit the meu.

Select CW mode by tapping M O D E .

§Connect a 6-W dummy load to the BNC jack.

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.

§

Set

§

Hold T U N E ; wait until VFO B shows 6 . 0 W.

§

Tap X M I T to exit TUNE.

§

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

§

Save your configuration using KX2 Utility.

§

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

§Tap X M I T to start SSB bias calibration.

§

Exit the menu by tapping D I S P .

§Save your configuration using KX2 Utility.

39

PWR

to exactly 6 . 0 watts (pg. 19).

Transmit Carrier

Transmit Opposite Sideband

In SSB and some data modes, a transmitter’s primary
signal may be accompanied by a weak unmodulated
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. This signal should
be suppressed (or nulled) to minimize interference tonearby stations. The TXSBNUL menu entry is used forthis purpose.

This procedure requires a spectrum analyzer,
and is normally done only at the factory.
Instructions available on request.

This procedure requires a spectrum analyzer,
and is normally done only at the factory.
Instructions available on request.

40

Menu Functions
Hold M E N U to enter the KX2’s menu. Tap or hold this switch to exit. Up to four menu entries that you’d likequick access to can be assigned to programmable functions PF1-PF4 using P F n , the programmable function switch(pg. 25). 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. Theirparameter values are locked by default, as indicated by the lock symbol on the display. To reveal all tech-mode
menu entries, set MENU:TECH MD to O N . To change any tech-mode parameter, you must first unlock it byholding F R E Q for about 3 seconds. This turns off the lock symbol.
Entry
2 TONE

Default
OFF

AF LIM

NOR 030

AFX MDDelay

AGC MDON

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 .
Adjustable AF output limiter for use when AGC is turned off (MENU:AGC MD).
This can protect your ears if a large signal appears. Signals or noise above thethreshold will sound distorted due to the limiting, reminding you to back down AF
gain (or RF gain, if you’re using MENU:RF GAIN to control receive gain).
Typical settings for those who often turn AGC off are 17 to 23.
D E L A Y setting (default) provides quasi-stereo audio, reducing operating fatigue
when using stereo headphones or dual external speakers.
Some operators prefer to turn AGC off and control RF gain manually. This can bedone with the preamp and attenuator, or using MENU:RF GAIN. (When AGC is
41

off, the AGC icons on the LCD change to A G C - , with the “minus” sign meaning“off”. Turning AGC off also disables noise reduction.)

AGC SPDSLOAGC*THR

007

ALT MDNOR

If an uncomfortably-strong signal appears in your headphones or speaker with
AGC off, reduce the threshold of the AGC-off audio limiter (MENU:AF LIM).
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 (007): 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 be held closein 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.
CW mode: If set to N O R , CW normal will be in effect on the present band. Set to
A L T to use CW reverse mode instead (R E V icon turns on). CW normal uses LSB(lower sideband), while CW reverse uses USB (upper sideband). This selection
affects the direction of VFO tuning for increasing pitch as CW signals are tuned in.
In some cases switching from one to the other can reduce QRM.
SSB mode: If set the N O R , the sideband normally used on the present band will
be in effect: LSB on 160, 80, and 40 meters, and USB on 60, 30, 20, 17, 12, and 10
m. Setting ALT MD to A L T will select the other sideband for the present band.
42

AM MODEON

AMP HRSN/A

DATA modes: DATA A and PSK D normally use USB, while AFSK A andFSK D use LSB. A L T selects the other sideband (data reverse) for the current data
submode, turning on the R E V icon.
Set to O F F if AM operation is not planned. You can copy AM signals using SSB
modes.
Shows total amp hours used by the KX2. This is useful for testing battery packs,
estimating remaining battery charge, or tracking the amp hours needed to complete
one or more objectives (e.g., a certain number of QSOs at a given power level).
The value is preserved on power-off, so it can show amp hours used over any
number of operating sessions. Holding C L R resets the value to 0.000; this is
typically done after swapping in a fresh battery. (Amp hours is also one of thespecial VFO B displays; tap D I S P , then rotate VFO B until you see n . n n n A H .
This display persists during transmit so you can monitor the rate of increase.

ANT.X SW

1ATU DATA

SET 1

In receive mode, the amp hour value will go up by .001 every 20-25 seconds. In
transmit mode, the value will go up by .001 every 2 to 10 seconds, depending on
operating mode, power setting, and antenna load impedance (all three can affectcurrent drain).
This menu entry (eXternal Antenna switch) can be used to remotely select antenna
1 or 2 on the KXPA100. Requirements: (1) a KXPA100 with the KXAT100 ATU
option must be connected to the KX2 via the amplifier control cable; (2) the KX2’s
PA MODE menu entry must be set to O N .
The KX2 stores two full sets of per-band data for the internal ATU (KXAT2). Thismenu entry selects which set to use. Typically SET 1 is used at a home location,and SET 2 for field operation. The two sets can also be used in cases where twoantennas are available for a given band. (Note: This menu entry has no effect on
KXAT100 ATU data, which is already stored separately for each of the KXPA100
amplifier’s antenna jacks. The KX2 can remotely switch KXPA100 antennas using
the ANT.X SW menu entry.)
Holding C L R while in this menu entry clears stored LC data only for the currently
selected set on the present band.
In the ATU DATA and ATU MD menu entries, tapping A T U shows the present
43values of L (inductance), C (capacitance) and N (L-network configuration). Thisapplies only to the internal ATU (KXAT2). The displayed data format is
LxxCxxNy. <xx> is a 2-digit hexadecimal value that, when converted to binary,shows which ATU L or C relays are engaged. <y> shows which side of the Lnetwork the capacitance is on: Nt = TX side, and NA = antenna side.
ATU MD
ATU.X MD

Not Inst

Normally, this menu entry’s name is ATU MD, and it controls the mode of the
KX2’s internal automatic antenna tuner (KXAT2 option).
If a KXPA100 with a KXAT100 ATU option is connected via the remote-control
cable, and PA MODE is O N , the menu entry changes to ATU.X MD (.X =eXternal). In this case the menu entry controls the auto-tune mode of the
KXAT100.
The parameter is normally set to B Y P or A U T O . Modes L 1 - L 7 , C 1 - C 7 , and C t
are used to test the KXAT2’s relays and L-network (not applicable to the
KXAT100).
Holding C L R while in this menu entry clears stored LC data for the present band.
If the KXAT100 is in use, the data for the currently selected antenna is cleared. If
the internal ATU is in use, data for the current ATU DATA set is cleared.

AUTO INF

NOR

AUTO OFFINFINITE

AUX 1 and
AUX 2

OFF

If set to A N T C T R L , the KX2 will send band data (“automatic info”) to its ACC
jack for use with devices such as SteppIR™ antennas. The data is sent on every
band or mode change, and once per second as the VFO is moved. See pg. 35.
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.
Used to set the KXIO2 option module’s AUX outputs to ON or OFF on a per-bandbasis.
Details: The AUX jack provides a ground (0 V) and two open-drain output
signals: AUX 1 and AUX 2. Open-drain outputs simulate a contact closure to
ground when in the ON condition, and are floating (high-impedance) when OFF.
Typically, the ON state would be used to turn on a relay connected to a DC supply
voltage (28 V max, 150 mA max).
44

The two outputs could be used singly or in combination to switch an external
device such as an antenna switch, select taps on a loading coil, etc. This could be
especially useful during mobile operation. (Note: Elecraft does not yet offer any
products that make use of the AUX outputs, but may in the future.)
BAT MIN

10.0

BKLIGHTON

COR LVLNOR 0.1

CW IAMBA

CW KEY1

TIP=DOTCW KEY2

LFT=DOT

CWT

OFF

Low-battery warning threshold. The default (1 0 . 0 volts) is sufficient for use withsome 12 V batteries such as gel cells, as well as for the specified 11 V Li-ion
battery pack. If the internal battery or external supply/battery voltage drops below
the selected level, the operator will be alerted with B A T L O W messages every
few minutes. Regardless of this setting, the KX2 will turn itself off if the supply
voltage drops below 7.5 V.
To extend battery life, turn the backlight and preamp off when not needed, and use
headphones rather than the internal speaker.
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.
Sets the carrier-operated-relay (COR) threshold. The COR is used to detect, andprotect the KX2’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 a KXPD2 (or 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, oras an input for an external keying device (keyer, computer, etc.).
When set to O N , the upper half of the S-meter becomes a tuning aid for CW,
PSK31/63 (PSK D mode), or RTTY (FSK-D mode) signals. Also, when CWT is
on in CW or PSK D modes, the manual signal spotting function of the KYR45

CW WGHT

1.25

SPT/MIC knob changes to auto-spot (pg. 21). In this case the KX2 will attempt toto tune in CW or PSK31/63 signals automatically.
Adjusts element/space timing ratio (weight) for the internal keyer.
Additional functions of this menu entry, via numeric keypad:
Tap 1 to select S S B - C W (default) or S S B + C W (allows CW in SSB modes).
When CW-in-SSB is in effect, tapping the KYR-SPT/MIC knob in SSB mode
alternates between keyer speed and mic gain rather than CMP/ALC and SWR/RFtransmit metering. CW transmit in SSB mode is not available if SPLIT is on.
Tap 3 to select N O R Q S K (default) or F S T Q S K . The FST (fast) setting
provides somewhat faster receive recovery time, while NOR (normal) is lesssusceptible to audio artifacts from noise and nearby interfering stations.
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 any SSB/CW mode change (V F O O F S ).
V F O N O R , the default, disables the offset. Automatic offset is useful whenmixed-mode QSOs are necessary, as during fading. Note: Pitch matching forautomatic offset will be more accurate if USB is paired with CW reverse, and LSBwith CW normal. See MENU:ALT MD.

DUAL RXOFF

FW REVS

N/A

KXIO2

Not inst

Set to A U T O to enable Dual Watch (pg. 25). 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.
Rotate VFO A to see firmware revisions: MCU (µ C , shorthand for
microcontroller), DSP (d S P ) , and KXPA100 amplifier MCU if applicable (P A ).
Tap 1 to see the RF board revision, e.g. “RFPCB=A” for rev. A.
If a KXIO2 module is installed, set the parameter to N O R , then exit the menu andturn the KX2 off/on. To set the time, use the TIME menu entry. Use the RTC ADJ
menu entry to improve the clock’s long-term accuracy if desired.
Note: The real-time clock circuitry must normally be powered by either the KX2’s
internal battery or an external power source. As a convenience for recharging thebattery, which must be done externally to the KX2, the clock will keep time for up
46

LCDTESTLED BRT

OFF
4

LOGGINGOFF

to about 2 hours with no power supply or battery connected. This capability isprovided by a supercapacitor on the KXIO2 module (see pg. 7).
The KXIO2 also provides two open-drain signals on its AUX jack. These could be
used for antenna switching or other applications. See the AUX 1 and AUX 2 menu
entries.
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).
When using the KX2 hand-held, or if operating time is very limited, logging may
be inconvenient. The KX2 can capture up to 2048 transmitted characters, alongwith time, band, and mode, so you can update a paper or electronic logbook later
on. To enable logging, set this menu entry to ON. Logging applies to CW (C),PSK-D (P) and FSK-D (F) modes, and only when using the internal keyer.
To take advantage of time stamping, either set the time on every power-up of theKX2 (MENU:TIME), or install the KXIO2 option module (see Options).
When logging is enabled and there’s room available, the DVR icon (above the Smeter) flashes slowly. Outgoing text decode is turned on, allowing you to makesure you’ve sent call signs accurately. If you fill the log, LOG FULL is flashed.
To review log text, tap DISP and use VFO B to find the LOG display. The VFO A
knob can then be used to scroll. Time/mode/band (MHz) are shown on VFO A(e.g., “0023 C14”); text is shown on VFO B. Holding CLR erases the entire log. To“dump” the log, send “LG;” to the KX2 via KX2 Utility’s Command Tester screen.
Tips: To conserve space, use message buffers (MSG) to send CQs, name/QTH,
etc. Messages are recorded in the log. To start/stop logging quickly, assign
MENU:LOGGING to a programmable function switch (PF1-PF4).

MIC BIASONMIC BTNPTT
UP.DN

Set to O N for the Elecraft MH3. (Not applicable to the internal mic.) You may
need to try both MIC BIAS settings to see which works best with other mics.
Monitor your transmitted signal with another receiver when testing mic audio.
If your mic has both a PTT switch and UP/DN buttons, set the parameter to
P T T U P . D N . This applies to the Elecraft MH3. If the mic has PTT but no UP/DN
47

MSG RPT6

PA MODEOFF

buttons, use P T T . Otherwise, use O F F . This setting applies to most headset-mics,
including the Heil models available from Elecraft. Third-party mics may not have a
KX2-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. 20).
Message repeat interval in seconds (0 to 2 5 5 ). To repeat a message, hold amessage button ( 1 – 3 ) rather than tap. A 6 - 10 sec. interval is about right forcasual CQing. Shorter intervals may be needed during contests, and longer forperiodic CW beacons.
Sets the operating mode for Elecraft KXPA100 amplifier and its internal ATU.
Set to O N only if the KX2 is connected to the KXPA100 via the KX2 Accessory
Cable (KX2ACBL), which plugs into the ACC jack at the KX2. This allows the
KX2 to control the amplifier’s output power and ATU tuning as described in the
KXPA100 owner’s manual. ATU MD becomes ATU.X MD in this case, and the
ANT.X SW menu entry can be used to switch antennas at the KXPA100.
Set to O F F otherwise.
If PA MODE is set to P out CAL, a KXPA100 is connected via the remote-control
cable, and PWR is set to CAL 75W, going into TUNE mode will calibrate the
KX2’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.
Sets the CW sidetone pitch in kHz. This is also the pitch of CW signals whencentered in the receiver’s passband. Note: In PSK-D mode (PSK31/63), the center
pitch is 1000 Hz (fixed). In FSK-D mode (RTTY), the mark tone is 915 Hz (fixed).

PITCH

0.60

REF CAL

25.000.000(+/- 1 kHz)

Used to calibrate the KX2’s synthesizer; normally done at the factory. VFO A is
used to set the reference frequency (typically 24.999-25.001 MHz). Refer to pg. 38
for calibration details.

RF GAIN

NOR–0 dB

Normally, RF GAIN is set to N O R - 0 d B (no gain reduction). However, some
operators prefer to turn automatic gain control off (using MENU:AGC MD) andadjust RF gain manually, maximizing dynamic variability of received signals. As
RF GAIN is advanced past -5 dB, a single bar on the S-meter starts at S-2 andmoves upward as a reminder of how far gain has been reduced (-5 dB/unit).
48

If desired, MENU:RF GAIN can be assigned to PF1-PF4 (pg. 25) for quick access.
Note 1: If you plan to turn AGC off as described above, you should set up the
MENU:AF LIM parameter to avoid painful audio volume on strong signals.
Note 2: RF gain is reset to - 0 d B on power-up. Otherwise the operator might not
be aware of a previous gain reduction used under different band conditions.

RS232

4800 b

RTC ADJ0

RX EQ-------(+0 dB,
each band)

RXSBNUL

GAIN nnn

Note 3: As is the case with many software-defined transceivers, the KX2’s RF
GAIN control is actually an input scaling factor applied within the DSP itself.
Reducing RF gain doesn’t impact the strength of signals seen by the A-to-D
converter (ADC; see glossary, pg. 66). Gain ahead of the ADC can only be reducedby turning the preamp off, and (if necessary) turning the attenuator on.
This sets the RS232 (or USB) communications rate in bits per second (bps). During
firmware download (via KX2 Utility), the baud rate is set automatically to 38400
baud. It is then restored to the value selected in this menu entry.
This parameter can be adjusted to improve the long-term accuracy of the real-timeclock on the KXIO2 option. (MENU:KXIO2 must be set to N O R to use the RTC.)
Monitor your clock's accuracy over 24 hours, preferably at your typical ambient
operating temperature. (The KX2 can be turned off during any portion of thismonitor period, as long as an internal battery or external supply is attached.) If it's
off by more than +/- 2 seconds per day, use RTC ADJ to compensate. For example,
if it's slow by 5 seconds per day, set RTC ADJ to "-5 SEC". Allow a few hours,
minimum, before making a further correction.
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 0 - 7 to select an AF
band. VFO A selects boost/cut. Hold C L R to reset all bands to +0 dB.
CW and SSB mode RX EQ are separate. Not applicable to DATA modes.
Used to null (reject) the receiver’s opposite-sideband image. 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 160-10 meter signal
source (such as an Elecraft XG3); instructions are available on our website.
49

Also see Receive Opposite Sideband calibration, pg. 39.
SER NUM
SW TEST<S/N>
OFFYour KX2’s serial number, e.g. 0 5 0 0 0 . Cannot be changed.
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.

SW TONEON

If set to O N , switch presses generate audible feedback tones. If set to C O D E n n ,Morse code characters are generated at n n WPM on control activation. The normal
D I S P switch function (special displays) is not available in this case. Instead, a tapof D I S P reads out the operating mode and frequency in kHz, e.g. “U 238” for USB
on 7.238 MHz. (Plain-text description of the full Morse UI available on request.)
Holding the A P F / A N switch during power-on will also turn on Morse feedback.
Switch tone volume is the same as CW sidetone volume. It must be adjusted in CW
mode, using
MON.

TECH MD
TIME

OFF
N/A

TUN PWR

NOR

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.
Set to O N to reveal Tech Mode menu entries (those marked within this list).
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. 23). Time is only
maintained if a KXIO2 option module and an internal battery are installed.
Also see the RTC ADJ menu entry, which may be used to improve the long-term
accuracy of the real-time clock.
Note: The clock circuitry must be powered by the KX2’s internal battery or an
attached power supply. Refer to the KXIO2 menu entry for details.
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.
Note: TUN PWR does not pertain to A T U T U N E , which uses 2 or 3 W (KXAT2)
or 5 W (KXAT100).
50

TX BIAS
TX CMP

ppp qqq
0

TXCRNULTX DLY

1 nnnnNOR 005

Transmit bias constants. See Transmit Bias, pg. 39.
Transmit speech compression (SSB mode). A setting of 20 (dB) is a goodcompromise between SSB signal talk power (“punch”) and good fidelity. Set to 0
(default) when doing 2-tone IMD testing. Note: TX CMP is automatically set to 0
in audio data modes (DATA A and AFSK A).
Used at the factory to null the transmit carrier on each band. See pg. 40.
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-10 m and the other for transverter bands. NOR (5 ms) is
recommended in most cases. A delay of up to 20 ms can be set, but use thesmallest delay possible since longer delays can add some timing variation in CW
mode at higher code speeds.

TX EQ+0 dB,
each band

Transmit audio graphic equalizer (applies to SSB mode only). Functions the sameas RX EQ, above. TX EQ can be adjusted during transmit.
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.

TX GAIN

ALC nnShows whether transmit ALC (automatic level control) is enabled, along with thetransmit gain constant for the present band (nn). The gain constant is updated
whenever the T U N E function is used at exactly 6 . 0 W and SWR is 2.0:1 or lower.
See Transmit Gain calibration procedure, pg. 39.
If a KXPA100 amplifier is connected via the remote-control cable, PA MODE isON, and PWR is 10 W or higher, the TX GAIN parameter shows the KX2 drive
level for 75 W output at the KXPA100. If the drive value is preceded by the letter‘A’, it was obtained from the KXPA100 (factory calibration value). If the drive
value is preceded by the letter ‘t’, it was obtained by doing P out CAL at 75 W at
the KX2 itself (see MENU:PA MODE). Holding C L R will erase the KX2’s CAL
value on the present band, restoring the ‘A’ value (from the KXPA100).
This menu entry is also used to turn transmit ALC on/off. It can be turned off fortransmit testing purposes by tapping A T U while in this menu entry. (This is NOT
51

necessary for any operational purpose. In all modes, ALC is optimized for low
distortion.) When ALC is turned off, a (-) sign is added to the parameter, e.g.
- A L C n n . Also, an asterisk is added to the P W R control value when it is being
adjusted (e.g. 5 . 0 W * ). With ALC off, the displayed power level will not change;
the control functions as a fine power adjustment, and its effect must be observedwith an external instrument.
TX GATEOFF 0

TXSBNUL

GAIN nnn

Set at factory to null transmit opposite sideband. See pg. 40.

VFO CRS

Per-mode

Tuning rate selection for VFO A and B when coarse tuning is selected (using
R A T E ). Also applies to offset tuning of VFO A (via the OFS/B knob) when both
RIT and XIT are turned off.

VOX DLY

0.00 (CW)

If VOX MD is set to O N in the current mode, this menu entry sets the VOX delay
time in seconds (recovery time from transmit to receive). In CW mode, the default
delay (0 . 0 0 ) also turns on the Q S K icon, indicating the fastest possible break-in.
(See CW WGHT menu entry for additional QSK settings.)
Independent VOX delay times are saved in SSB and audio data modes (pg. 28).

0.50
(SSB/data)

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 turn thenoise gate on/off. Use VFO A to set the desired threshold. Since there’s no visualindication that transmit audio is below the threshold, you should adjust it using thetransmit voice monitor (MON), ideally while using headphones. Set the thresholdhigh enough to cut off transmit audio due to local noise, but not so high that it
causes your voice to drop out too frequently.

VOX GN

030

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 (1 0 -2 0 ).

VOX INH

000

Adjusts immunity of the VOX circuit to false triggering by speaker audio. (Alsoknown as anti-vox.) A setting of about 3 0 is a good starting point. If receive audio
from a speaker trips the vox, increase the setting.

VOX MD

ON (CW)

If VOX is O F F , transmit must be started by tapping X M I T (otherwise known as
PTT, or push-to-talk operation).
In CW mode, setting VOX MD to O N allows “hit-the-key” transmit. In SSB mode,

OFF (SSB,
AF data)52

VOX=O N allows transmit to start when you start speaking. In audio data modes,
VOX starts transmit when a computer connected to the mic jack outputs an audio
signal. VOX is always O N in PSK-D and FSK-D modes; PTT is not available.
VOX cannot be used with the built-in microphone.
WATTMTR

1.00

Wattmeter calibration parameter. If an external, known-accurate wattmeter reads
lower than the KX2’s wattmeter, decrease the parameter value (and vice-versa).
Internal wattmeter accuracy may vary by up to +/- 1 dB, per band.
On transverter bands, the menu entry name changes to WMTR XV.

XIT

OFF

XIT is short for Xmit Incremental Tuning. Set to O N to offset the transmit
frequency without affecting the receive frequency. The X I T icon will turn on. Use
OFS/B to set the offset (+/- 9.999 kHz). This is also the offset that will be usedwith R I T (pg. 16). If you use XIT frequently, you may wish to access it via P F n .
XIT can be useful for applying a small offset to your transmit signal to improve
copy by other stations, especially in PSK-D mode (such an offset must be
determined experimentally). It can also be used as an alternative to SPLIT, leaving
VFO B free for other purposes. For more on XIT and RIT, see pg. 16.

XVn ONNO

Tap 1 – 7 to select the applicable transverter band display (1 - 7 ). Set parameter to
Y E S to enable or N O to disable.

XVn RF

144

Lower edge for transverter band <n> (1 -7 ); 0 -2 4 9 9 9 M H z . (Tap 1 – 7 to selectapplicable transverter band.)

XVn IF

28

Specify KX2 band to use as the I.F. for transverter band <n> (1 -7 ) . (Tap 1 – 7 toselect the transverter band.) I.F. selections include 7 , 1 4 , 2 1 , and 2 8 MHz.

XVn PWR

H 0.1

Sets upper limit on power level in watts for XVTR band <n>. Tap 1 – 7 to selectband. Note: The KX2 does not have a low-level transverter port, so transverters
must have their own T/R switching and be able to handle the specified power level.

XVn OFS

0.00

Offset (– 9 . 9 9 to +9 . 9 9 kHz) for transverter band n (1 -7 ). (Tap 1 – 7 to selectband.) Compensates for oscillator/multiplier chain errors in external transverters.

53Troubleshooting
The most common symptoms and their causes are listed below, in three categories (general, transmit, and receive).
Most problems are related to control settings. If the problem persists, please contact Elecraft support (see pg. 70) or
post a question on our email forum.

General
§
§
§
§
§
§
§
§
§
§

§
§
§

M C U L D shown on LCD, and TX LED flashing: Do a forced firmware load (pg. 34).
* * * * * shown on LCD permanently: This may indicate that the KX2 did not power-down correctly.

Disconnect power for a few seconds, then try a forced firmware load (pg. 34).
Display backlight turns on, but then turns off upon release of switches: Disconnect all external equipmentfrom the KX2. Verify power supply or battery voltage is between 8 and 15 V.
E R R n n n (error) message appears in the VFO B area: Refer to Error Messages (pg. 59).
Scrolling message appears in the VFO B area: Refer to Scrolling Alert Messages (pg. 62).
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 OFS/B until the supply
voltage display appears). If the batteries are at their normal voltage, you may have MENU:BAT MIN set to thewrong low-battery warning level. See this menu entry for recommendations.
Can’t turn power on: Check the power cable. If running from an internal battery, make sure it’s charged.
Can’t turn power off: If the display remains on, or the unit is otherwise unresponsive, disconnect the power
supply. (If an internal battery pack is in use, also remove the 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 (if applicable),and DC cabling. The KX2 provides both voltage and current monitoring (pg. 23). Also see Transmit andReceive 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 thelatest KX2 firmware. Review the release notes for changes that may be related to your symptoms.
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 KX2 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 .
54

§
§

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: If using a mic other than the MH3, set MIC BTN to OFF.

Transmit
§
§
§

§
§
§
§

§
§
§

B N D E N D : Indicates an attempt to transmit outside the ham bands.

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.
H I C U R o r H I S W R w a r n in g : 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 KX2 may
do this automatically. If this doesn’t reduce the current or reflected power to safe levels, the KX2 will drop outof transmit mode.)H I T E M P w a r n in g : 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 if necessary.
(The KX2 may automatically reduce power, drop out of transmit mode, or turn itself off.)
KX2’s right side panel is hot to the touch: The right side is used as a heat sink, so it it normal for it to feelquite warm during long transmissions. The panel will run cooler if you use shorter transmissions, lower power,
or a lower supply voltage. If operating in sunlight, try to orient the right side panel away from the sun.
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 F R E Q for 3 seconds, then tap A T U
This will turn off the (- ) sign in front of A L C .
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 (see MENU:VOX). If VOX is off(PTT-CW), you must tap X M I T before sending; otherwise only a sidetone is generated . (3) You may be in
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: You may also be working into a high-SWR load and/or using a low supply voltage. Also
try redoing Transmit Gain calibration (pg. 39). Note: Max power also varies per band.
Inadequate transmit carrier or opposite-sideband suppression: The voice- and audio-data carrier andopposite sideband will typically be down 60 dB or more at 5 watts output. If either is significantly higher than
this level, the Transmit Carrier or Transmit Opposite Sideband calibration steps (pg. 40) can be performed.
These procedures require a spectrum analyzer and are normally done only at the factory.
55

Receive
§

§

§
§
§

§

§
§

H I R F I warning, preamp turns off, or R X icon turns on: The KX2 protects itself from high received signal

levels. First the preamp is turned off, if it was on. The second step taken by the KX2, if necessary, is to turn on
the RF attenuator. The receive overload icon (R X ), near the A N T icon, will turn on. Once signals return to asafe level for 5 seconds, the 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-operated-relay(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 the present low-passfilter. When the relay opens, signals will drop by 40 to 60 dB, protecting the KX2. The relay will close again
shortly after the signal drops. If the COR is being repeatedly activated, try moving the antennas farther apart.
You can also increase the COR threshold, at your discretion; see MENU:COR LVL.
H I C U R warning: May indicate that speaker volume is too high; gain is reduced by the KX2 in this case.
No received signal: Check (1) antenna connectors; (2) RF gain too low (set RF gain menu entry fully
clockwise, to – 0 d B ); (3) bandwidth too narrow (tap F I L and rotate AF GAIN/MON to widen the passband);(4) MENU:REF CAL parameter not adjusted properly.
Signals very weak below 3 MHz: The KX2 is designed primarily for use on 80-10 meters (3 to 30 MHz).
Receive capability extends down to 500 kHz, but as shown in the Specifications section, signals will be
progressively attenuated below 3 MHz due to high-pass filtering in the T/R switch. (This filtering is intended toprotect the T/R switch PIN diodes.) Attenuation will be approximately 15-20 dB in the 160-meter band, andmuch greater at the low end of the AM broadcast band. Sensitivity should still be adequate for reception ofstrong AM broadcast stations, useful in an emergency. Also see next item regarding mixer images in this range.
Signals in the 500 kHz-3 MHz range appear to be off-frequency: These may be mixer images of signals
higher up in frequency. They appear because the KX2 does not provide filtering below 3 MHz (see above).
Generally, if an AM broadcast signal in the 550-1700 kHz range can be tuned in at an exact multiple of 10 kHz
in LSB or USB mode, then it is a legitimate signal. Those tuning in at non-multiples of 10 kHz are likely to be
images.
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) makesure MENU:RF GAIN is set to -0 dB.
Spurious signals (“birdies”): All receivers exhibit some birdies. Most will be inaudible with an antennaconnected. In the KX2, 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), 500-900 kHz
56

§
§
§
§

§

§

(DC-DC converter oscillators, CMOS RF switches). In the unlikely event that a birdie interferes with operation,
try CW reverse (MENU:ALT MD), or auto-notch (A P F - A N switch, SSB mode only).
Opposite-sideband images heard: Opposite-sideband suppression is typically 50-60 dB. If images appear too
high in amplitude, Receive Opposite Sideband suppression may have to be adjusted (normally done at thefactory; see pg. 39).
“Frying pan” or buzzing sound in headphones: Headphones may not be plugged in all the way.
Mobile installation noise: If the 12 V DC accessory jack in a vehicle causes interference to the KX2’s
receiver, improve filtering of the DC supply.
Low-level signals are heard that don’t change as the VFO is rotated: It’s possible for extremely strong
signals to create audible artifacts, due to AM detection at the mixer, that are not affected by tuning the VFO. If
this occurs, first try turning off the preamp. If that doesn’t suffice, turn on the attenuator. If the source of suchsignals is a nearby transmitter (such as at Field Day), reorient or move antennas, or use an external band-passfilter.
KX2 VFO signal is heard in a nearby receiver: A receiver whose antenna is in very close proximity to the
KX2’s may pick up the KX2’s VFO signal when both are set to about the same frequency (+/- 8 kHz). Try
separating or reorienting the antennas. If that isn’t possible, try turning on the preamp and/or attenuator at eachradio. This will often improve isolation between the local oscillator and the antenna jack.
Internal speaker distortion at high volume: The KX2’s small internal speaker is not intended for use in highnoise environments, such as in a noisy vehicle or outdoors in high winds. If audible artifacts occur, reduce AF
gain or switch to headphones or an external speaker. (Stereo headphones or dual external speakers will allow
the use of audio effects and dual watch.)57

Parameter Initialization (EEINIT)
Parameter initialization should not be done without first consulting Elecraft customer support. We canhelp you solve most problems without taking this step. Also, please look for your symptoms in the
Troubleshooting section above.
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 KX2 Utility program and use the Save Configuration function to save your present
firmware configuration. (Otherwise, you’ll need to re-do calibration steps after EEINIT.)
Turn the KX2 off (using the KX2’s on/off switch combination, not your power supply).
Hold in the N B knob with your left hand. Then turn power on with your right hand by holding R A T E and A / B
together for about 3 seconds until the LEDs all turn on. Finally, release the N B knob after a 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 any error
messages.
Restore all parameters using the Restore Configuration function of the KX2 Utility program. Then turn power
off and on again. See if the original problem has been resolved. If not, contact Elecraft. Note: Elecraft
maintains configuration files for all KX2s sold. Your original configuration file can be sent to you via email onrequest.

58

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
you have consulted Elecraft customer support.
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 ATC,ERR ATI

Problem
KXAT2 module not accessible:
ATC = I/O expander C
ATI = I/O address mismatch

ERR ATRKXAT2 relay failure (on VFO
A, d = n n n identifies the failing
relay, e.g. 0 0 1 for relay K1)

ERR DS1ERR DS2ERR DSE,DSXNo 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

Troubleshooting steps
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 the 8-pin connector iscorrectly lined up with its mating connector on the RF
board.
Turn power off for 10 seconds, then back on. Remove andre-install the KXAT2 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. Reload
MCU and DSP firmware. If this doesn’t correct the
problem, save your configuration using KX2 Utility, thenconsult customer support to see if you should do an
EEINIT (pg. 58). If this corrects the problem, restore yourconfiguration using KX2 Utility. If error codes persist,write down all error codes and associated data values(displayed on VFO A) and contact Elecraft.
The main microcontroller (MCU) may be defective.
59

ERR EE2

ERR FW2ERR IOAERR IO2

test failed
External EEPROM read/write
test failed

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.

General firmware problem.
d = n n n identifies the type oferror (report to Elecraft).
RF board I/O expanderunresponsive.

Follow steps shown for ERR DS1.

ERR KEY,ERR PTTKXIO2 module error (realtime-clock). d = n n n is the
specific error code (report to
Elecraft).
Attempt to key the transmitteror activate PTT during poweron sequence. (Note: If ERR
PTT occurs, VOX transmit isdisabled in all modes. Reenable using MENU:VOX.)ERR OSC

Synthesizer IC unresponsive

Turn power on. Reload MCU and DSP firmware. If error
codes persist, turn power off, remove all option modules(KXAT2 and KXIO2), and turn power back on. Turn off
associated option module enables in the menu (pg. 36),
then turn power off and back on. If this corrects the
problem, re-install the option modules one at a time to see
which one may be causing the problem. If errors persist,the Control Panel or RF Board may have to be replaced.
Write down error codes and data values (on VFO A)
before contacting customer support.
Turn power off for 10 seconds, then back on. If thisdoesn’t correct the problem, re-seat the KXIO2 moduleand repeat. If the problem persists, replace the KXIO2.
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
KXPD2 (or KXPD3) keyer paddle. Turn power off, thendisconnect the KXPD2 or KXPD3 (if applicable) andeverything plugged into the left side panel, except for the
power supply. Turn power back on. If the problem has
disappeared, plug devices back in one at a time to see
which one caused the error.
Follow steps for ERR IOA.
60

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

RF board may be disconnectedfrom Control Panel board
RF board relay failure (on VFO
A, d = n n n identifies the failing
relay, e.g. 0 0 1 for relay K1)
Transmit power MOSFET Q6
or Q7 bias out of range
Transmit gain constant out of
range

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 band
Transmit attempt without firstcalibrating gain on present band
Power amplifier temperature
sensor out of range
VOX activation detected at
power-on

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. 39). If this doesn’t
correct the problem, reload a known-good Configuration
file using the latest version of the KX2 Utility. Customer
support can supply the original Configuration file if you
didn’t save one when you first received your KX2.
Perform Transmit Bias calibration (pg. 39). This is afully-automated procedure that requires no test equipment.
Reload a known-good Configuration file using the latest
version of the KX2 Utility. Customer support can supply
the original Configuration file if you did not save a
Configuration file when you first received your KX2.
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.

61

Scrolling Alert Messages
Certain conditions will result in an alert message scrolling across the VFO B display. These are listed below.
Alert Message

Description

CONNECT DATA IN TO MIC JACKIn AF data modes (DATA-A, AFSK-A), an external audio
source must be plugged into the mic jack. This disconnects
the internal mic.

NO MON WITH INT MIC+INT SPKR

If the internal mic and internal speaker are both in use, voice
monitoring (MON) is disabled to prevent audio feedback.

NR REQUIRES AGC MD ON

NR (noise reduction) cannot be used with AGC turned off. It
also does not apply in DATA mode.

TAP 3 TO TURN OFF TX ALCThe TX GAIN menu parameter (per-band gain constant) is
normally set automatically during TX gain calibration. The
parameter can be adjusted manually (not recommended), but
TX ALC must be turned off first.

TAP XMIT TO SET BIAS

When aligning TX BIAS, it is only necessary to tap XMIT.
This alert appears if the user attempts to manually adjust theparameter using VFO A.

TO UNLOCK, HOLD FREQ FOR 3 SEC

The current menu parameter cannot be adjusted until it isunlocked by holding the FREQ switch for ~3 seconds.

USE FSK-D, OR SSB WITH 2-TONE ON

TX sideband nulling (MENU:TXSBNUL) requires that
MENU:2 TONE be set to ON, and that the KX2 be in SSB or
FSK-D mode.

USE PHONES

DUAL RX (dual watch) cannot be used with the internal
speaker. Phones or dual external speakers are required, since
the audio associated with VFO A is routed to the left channel,
and VFO B to the right.

62

Theory Of Operation
This section includes a functional description of the KX2’s RF, control panel (CP), and option boards; a block
diagram; and a glossary of selected technical terms. Also see the KX2 FAQ (www.elecraft.com).

RF Board
The RF board contains all of the KX2’s RF circuitry as well as low-level baseband (AF) stages in the receive path.
The relay-switched low pass filters are used during both transmit and receive. The signal on the antenna side of thefilters pass through a forward/reflected power and SWR bridge to the antenna jack (BNC), or to the optional
KXAT2 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. T/R switching uses PIN diodes and CMOS switches for clean, silent transitions.
The RF band-pass filters are used for both transmit and receive. Filters are selected with PIN diodes. 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 the RF preamplifier and an attenuator. These provide
various tradeoffs between overall receive gain and noise figure (or MDS).
The RX mixer converts the RF signal to quadrature (8 kHz IF I and Q signals), which are low-pass filtered andamplified before being passed to the CP board for analog to digital conversion (ADC).
The TX AF Amp and TX mixer block converts baseband (AF I and Q) modulating signals to an RF signal whichis then routed to the T/R switching and band pass filters. This signal provides excitation to the 10 W power
amplifier (PA). The PA uses a pair of RF power MOSFETs. Temperature monitoring of the MOSFETS allows
automatic reduction of power if they become too hot during long transmit periods.
The optional KXAT2 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 seven inductors
and seven capacitors capable of matching a wide range of antenna impedances. The KXIO2 option incorporates areal-time clock (RTC) function, useful for logging and time-keeping. It also has two general-purpose outputs thatcan be used to turn on relays, etc., in external gear. These are open-drain outputs (the drain lead of a MOSFET
transistor). They act like contact closures to ground.

63

Control Panel (CP) Board
The CP (Control Panel) circuit board contains all of the KX2’s control circuitry as well as IF and AF stages for thetransmit and receive paths. It contains two on-board microcontrollers: one to manage the radio (MCU), and anotherto process all transmit and receive signals digitally (DSP).
The synthesized, digitally controlled local oscillator (LO) provides quadrature signals to the transmit and receive
mixers.
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 IF signal from the RF board is provided in low-level phase quadrature, or In-phase and Quadrature(I/Q). These signals are digitized by a very low power, high-performance analog-to-digital converter (ADC), thenpassed to the DSP for processing.
The baseband transmit signal is likewise provided in I/Q format to the RF board. A dedicated, high-performance
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.
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), and also optimizes dual watch capability, where the signals from VFOs A and B are routed to the left andright audio channels. If the internal speaker is used, the audio is monophonic, and is boosted by a separate speakeramplifier IC. Microphone audio (or low level audio from a computer or or other source) uses another ADC thatruns at all times to enable voice-operated transmit (VOX) operation.
The microcontroller unit (MCU) handles all user interface functions for the KX2, including 12 switches and 4
shaft encoders. It also handles timing, sequencing, and overall management of the radio. The MCU uses EEPROM
to store operator preferences, messages, and settings. An accessory port (ACC) provides a serial I/O 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 circuitry on the CP and RF boards. I2C(pronounced I-squared-C) controls the synthesizer IC. An SPI bus handles bandswitching, changeover between
receive and transmit, etc. The driver for the liquid-crystal display (LCD) is also controlled via the I2C port.
64

KX2 Block Diagram
W. Burdick, L. Johnson, R. Heineck, R. Friess
Rev: 02 May 2016

+12V Ext+3.3V and +1.2V Switching Regulators+5V, +3.3V and +1.8V Linear Regulators(LM78L05, LM78M05, MIC5265, LP2985, LM2671,
LM2831)

ATU (Option)
KXAT2
ATU
(7L & 7C)

ANTENNA

PWR/SWR BRIDGE

T/R Switch

80m – 10m

Rx RF
Preamp/Attenuators
NE46134

Tx PA
Temp
Sensor
LM20

Si5351
Temp
SensorLM20

RF Switch

80m – 10m

10W Amp2x
RD15HVF1

RF Switch

RxM
FST3257

Rx AF
Preampand LPF
AD8599 +OPA2209

p/o CP Board

Sin/Cos

I2C

Si5351
74VLC74

IQ ADC(48 kHz)PCM1803A(SE)

2 Megabyte
FLASH
Boot/Data
M25PX16
(SPI)

SP/PH
DAC
(48 kHz)
AIC3105ADSP21479
DSP

SPKR Amp
TDA7052A`
TxM
MCP23S17 IO
Expanders (SPI)

FST3253

KXIO2 Clock (Option)
PCF2123
NPIC6C596A(SPI)

Tx AF Amp
OPA4376

IQ DAC(48 kHz)PCM1773(SE)

SPI

RF BOARDK
E
Y

RECEIVE

Mic/Line
ADC(48 kHz)
AIC3105

LCD Controller
PCF85134(6V)

TRANSMITTx & Rx

RF Board SPI

Serial I/O(2N7002,
MMBT3904)

PIC
18F87K22

FP Controls(1 main enc, 3small enc w/
sw, 12 sw)

CP BOARD

65

EEPROM
24LC512Glossary of Selected Terms
The following terms are often used in the discussion of amateur radio transceivers and related equipment. All areapplicable to the KX2, used here to illustrate some of the concepts. Also see the ARRL Handbook.
________________
A-to-D or ADC (analog-to-digital converter): An integrated circuit that converts analog signals such as audio or
RF into digital form. 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, arethe actual frequencies of the radio signals (or TV, or cell phone, etc.). IF, or intermediate frequencies, are generally
somewhere between RF and AF. In a receiver, it is usually advantageous to convert RF signals to a lower IF at
which is it more practical to obtain gain or selectivity. These IF signals are then further converted to AF andamplified 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 or transmitter.
The KX2’s receiver includes a switchable attenuator (pg. 17).
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 KXAT2, pg, 33.)
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 human terms,
one dB represents a “just noticeable difference” between two signals. Mathematically, dB is derived from thelogarithm of the ratio of two signals. Receivers must handle signals over a huge range—in excess of 100 dB. dBm
is a more specific term that means “dB relative to 1 milliwatt” (1 mW) of power. 1 mW is thus “0 dBm.”
DC-to-DC converter: A device that converts one DC voltage into another. For example, the KX2 includes a very
efficient DC-to-DC converter that converts 12 V (nominal) at the DC input jack to 3.3 V for use by its low-voltage
circuitry. The advantage of a DC-DC converter is that when it steps voltage down, it steps current up (or viceversa). In this case, the 300 mA the KX2 consumes at 3.3 V might require only 100 mA at the 12 V power source.
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 digital form
(see A-to-D, above), while outputs from the DSP must be converted from digital to analog (see D-to-A). Use of DSP
66

techniques can result in greater versatility and smaller size compared to the equivalent analog circuitry. The KX2
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 usually 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).
IMD (intermodulation distortion): Unwanted signal products that are created in the various stages of a receiver ortransmitter. 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 to great lengths tominimize 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 KX2 hasa built-in keyer function, as well as an optional attached keyer paddle (KXPD2 or KXPD3, pg. 33).
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 DSP in the KX2 is a 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 KX2 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.
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 the radio(also see MDS).
SDR (software-defined radio): A radio that performs signal modulation, demodulation, filtering, and otherfunctions in software. Such software can execute internally (in a dedicated DSP IC, as in the Elecraft K3S, KX3, orKX2) or externally (in a general-purpose computer, as required with “black box” SDRs).
VFO (variable frequency oscillator): A signal source used to select a radio’s operating frequency. The KX2’s
large knob controls VFO A, while a smaller knob controls VFO B (see Using VFOs A and B, pg. 16).
67

Specifications
GENERAL
Frequency Range

Receive, 500 kHz - 32 MHz. See 500 kHz to 3 MHz sensitivity note below.
Transmit, 80/60/40/30/20/17/15/12/10 meter ham bands. (Consult factory for MARSor other non-ham-band coverage.) Transmit excluded in some ranges (by country).

Frequency Stability+/- 1 ppm typical at 25 C after 5-minute warm-up.

Antenna

50 ohms, BNC

Modes

USB, LSB, CW, DATA; built-in text encode/decode for CW/PSK/RTTY modes

VFOs

Dual VFOs; 150+ frequency memories; scanning/channel hopping

Accessory I/O

ACC: RS232 or USB port depending on selected adapter. Keyline: 30 V, 100 mA
max (pg. 9). AUX 1 and 2 (KXIO2): 28 V, 150 mA max.

Supply Voltage
and Current

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

Size and Weight

Size, less projections: 2.8 x 5.8 x 1.6” (7.2 x 14.7 x 4 cm); weight, less battery or
options: 13 oz. (0.37 kg)

RECEIVER*
Sensitivity (MDS),

500-Hz bandwidth-136 dBm (typ.), preamp on. Note: Sensitivity rolls off significantly below 3.0 MHz
due to protective high-pass filtering. Preamp-on MDS is typically -105 dBm at 1.5
MHz, and -80 dBm at 1.0 MHz, sufficient for emergency AM broadcast signal copy.

Image and I.F. Rejection

55-70 dB typ. From 3 to 32 MHz (varies with filter settings, mode, and band). Image
rejection from 0.5 to 3.0 MHz is not specified.

Audio Output

Internal speaker, 0.3 W typ.; headphones/ext. speaker jack, 0.1 W/channel (stereo)

Receive Features

8 band RX EQ, tunable I.F. passband width/shift, audio peaking filter (APF), noise
reduction, noise blanker, automatic notch filter

68

TRANSMITTER*
Output Power80-17 meters, 10 W PEP max (+/- 1 dB); 12 and 10 meters, 8 W PEP max (+/- 1 dB).
Recommended transmit duty cycle: 50%, all modes. (If power amplifier temperature or
current drain is too high, power will automatically be reduced.)
NOTE: When using over 5 W in SSB, DATA-A and AFSK-A modes, therecommended supply voltage is 12 V or higher to minimize transmit intermodulation
products. Higher power with lower voltages should be used only when necessary.

Internal ATU (KXAT2)

7 L/7 C network; matching range typ. 20:1 or higher. Rated power: 15 W.
Insertion loss (bypass mode): < 0.5 dB. Two different data sets available forhome/field use (see MENU:ATU DATA).

Transmit Features

Adjustable speech compression (baseband envelope clipping); 8-band TX EQ; VOX;
full and semi CW break-in with adjustable delay; diode T/R Switching; 3 DATA/CW
messages and 2 SSB (DVR) messages; automatic logging of DATA/CW text (seeMENU:LOGGING).

Carrier Suppression> 50 dB typ.

Harmonic / Spurious Outputs> 50 dB below carrier typ. @ 10 W

CW Sidetone/Transmit offset

400-800 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.

69

Customer Service and Support
Technical AssistanceTechnical assistance is available to all of our customers. We encourage you to use email for faster response to yourquestions. Email address is: support@elecraft.com. We typically respond to email the same day from 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. For faster
response, please use e-mail rather than calling the factory.

Repair / Alignment Service
If necessary, you may return your Elecraft product to us for repair, calibration or alignment. If you purchased your
Elecraft product from one of our Authorized Distributors, please contact them first. They can perform all of thefactory calibrations that can be made at the factory.
IMPORTANT:(1) REMOVE BATTERIES before shipping (see instructions on pg. 6).
(2) You must contact Elecraft before mailing your product to obtain Return Authorization to begin the returnprocess. When emailing, please provide your call sign, the product in question, and a description of what the
problem is. We will reply with an email that contains shipping instructions, and current information on repair fees
and turn-around times. Our repair location may be different from our factory location. We will give you the address
to ship your KX2 to at the time of repair authorization. Packages shipped to Aptos without authorization will incuran additional shipping charge for reshipment from Aptos to our repair depot

70Elecraft 1-Year Limited WarrantyThis warranty is effective as of the date of first consumer purchase (or if shipped from the factory, the date the product isshipped 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 time oforder. Elecraft products transferred by the purchaser to a third party, either by sale, gift, or other method, who is notdisclosed to Elecraft at the time of original order, are not covered by this warranty. If the Elecraft product is being bought
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 toyou by UPS ground service or equivalent to the continental USA and Canada. For Alaska, Hawaii, and other 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; orany performance malfunctions involving non-Elecraft accessory equipment. The use of acid-core solder, water-soluble
flux solder, or any corrosive or conductive flux or solvent will void this warranty in its entirety. Also not covered isreimbursement for loss of use, inconvenience, customer assembly or alignment time, or cost of unauthorized 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 the customer.
Elecraft will not be liable for any special, indirect, incidental or consequential damages, including but not limited to any
loss of business or profits.

71

IndexACC Jack, 9Advanced Operating Features, 23
AF Gain Control, 17
AF Limiter, 40
AFSK A Mode, 28
AFV, 23
AFX (Audio Effects), 25
AGC MD, 40
AGC Speed, 41
AGC Threshold, 41
ALC, 50
ALT MD, 15, 41
AM Mode, 22
Amp Hour Metering, 7, 23, 42
Analog To Digital Converter (ADC, A-to-D), 65
Antenna, 11, 38
Antenna Control (Auto-Info), 34
Antenna Switch (KXAT100), 42
Antennas, 10
Anti-VOX, 20
Attenuator, 17, 65
ATU data sets, 19
ATU Tuning, 19
Audio Effects (AFX), 25, 40
Audio Peaking Filter (APF), 18

Auto Info (AI Mode), 43
Auto Power-Off, 35
Automatic Antenna Tuner (ATU), 11, 19, 43, 65
Auto-Notch, 18
Auto-off, 43
Auto-Spot, 21
AUX Outputs, 9, 43
Backlight, 44
Band Selection, 15
Banner, Power-On, 30
Batteries, 43
Battery Installation, 6
Battery Warning Level, 44
Birdies, 55
Break-In Keying (QSK), 20, 21
Calibration Procedures, 37
Carrier-Operated Relay, 44
Channel Hopping, 24
Clipboard Mount, 7Clock, 49
Coarse Tuning Rate, 51
Code Practice, 21
Configuration, 35, 57
Control Groups, 5Counterpoise Wire, 772

Cross-Mode Operation, 30
Customer Support, 69
CW Keying Weight, 21, 30, 45
CW Mode, 21
CW Reverse, 15, 41
CW, Break-In (QSK), 20, 21
CW, Sending in SSB mode, 45
CWT, 18, 21, 44
CW-to-DATA, 21
DATA Mode, 28
Data Modes, 27
dB, decibel, 65
dBV, 23
DC-to-DC converter, 65
Digital Signal Processor (DSP), 65
Digital To Analog Converter (DAC, D-to-A), 65
Digital Voice Recorder, 30
Direct Frequency Entry, 15
Display (LCD), 13
Dual Watch, 25, 45
EEINIT, 57
Electrostatic Discharge (ESD), 66
Error Messages (ERR nnn), 53, 58, 61
Filter Center Frequency, 68
Filter Graphic, 13Filter Passband Control, 17
Firmware Revision, 33, 45
Firmware Upgrades, 33
Forcing a Firmware Download, 33
Frequency Memories, 24

Frequency Memory Editor, 34
Frequency Range, 67
Frequency Stability, 67
Front Panel, 5
FSK D Mode, 27, 28
Glossary, 65
Headphones, 8
HI CUR Warning, 54, 55
HI RFI Warning, 55
HI SWR Warning, 54
High Frequency (HF), 66
Iambic Keying, 35, 44
Intermodulation Distortion (IMD), 66
Keyboard, 34
Keyer, 19, 66
Keyer Paddle, 8, 44
Keying Weight, 21, 45
KX2 Utility PC Application, 33, 34, 57
KXAT2, 32, 35
KXIO2, 45
KXPA100, 19, 35, 47
LCD Backlight, 44
LCD Test, 46
LED Brightness, 46
Limiter, 40
Logging, 7, 13, 21, 27, 31, 34, 46
Low Battery Warning, 35, 53
Memories, 24
Memory Label, 24
Menu Functions, 4073

Menu Settings, 14, 35
Message Record/Play, 22
Message Repeat, 47
MH3, 32
Mic Bias, 46
Mic Function Buttons, 46
Microcontroller Unit (MCU), 66
Microphone, 8
Microphone Gain Control, 19, 20
Microphone Settings, 36
Microphone, Internal, 8, 20
Minimum Discernable Signal (MDS), 66
Mode Selection, 15
Noise Blanker, 18
Noise Reduction, 18
Notch Filtering, 13
Operation, 14
Option Module Enables, 35
Options, 32
PA temperature, 23
Parameter Initialization, 57
Parameter Save/Restore, 58, 59
PFn, 25
PGM, 9Power On/Off, 14Power Output Control, 19Power Supply, 5
Preamp, 13, 17, 66
Programmable Function Switch, 25
PSK D Mode, 28

PSK31, 28
QSK, 20, 21, 45
Quasi-Stereo (AFX), 40
Quick Memories, 24
Quick-Start Guide, 12Real Time Clock, 36
Receive Settings, 17
Reference Oscillator, 37, 47
Remote Control, 34
RF Board, 62
RF Gain Control, 47
RIT/XIT Offset, 16
RS232, 34, 48
RTC, 7, 36, 45
RTC Adjustment, 48
RTTY, 28
RX EQ, 26, 48, 50, 55
Scanning, 24
Self-Test, 33
Serial Number, 49
Sideband Selection, 41
Sidetone, 21, 47
Software Defined Radio (SDR), 66
Speaker, 8, 25
Specifications, 67
Speech Compression, 50
SPLIT and Cross-Mode Operation, 54
Split Operation, 29
SSB +CW, 45
SSB Mode, 20

74

SSB/CW VFO Offset, 26
Standing Wave Ratio (SWR), 11
Switch Test, 49
Switch Tones, 36, 49
Tech Mode Menu Entries, 49
Terminal Emulator, 34
Text Decode and Display, 21, 29
Theory Of Operation, 62
Time, 36
Transmit Bias, 49
Transmit Gain Calibration, 38, 50
Transmit Metering, 20
Transmit Noise Gate, 30, 51
Transmit Settings, 19
Transverter, 31
Transverter Control, 52
Troubleshooting, 53
Tune Power, 36, 49

Tuning Rate, VFO, 36, 51
TX EQ, 26, 50
TX Gain, 50
TX LED, 33, 54
Variable Frequency Oscillator (VFO), 66
VFO B Parameter Displays, 16, 23
VFO lock, 16
VFO Setup, 36
VFO Tuning Controls, 16, 36, 51
VOX Delay, 51
VOX Gain, 51
VOX Inhibit, 51
VOX Mode, 51
VOX Setup, 20
VOX, Voice Modes, 36
Warranty, 70
Wattmeter, 52
XIT, 5275