E L E C R A F T KX1 T R A N S C E I V E R
ELECRAFT KX1

12V

S1 3

5

ANT.

7 9 +

RX
TX
RF 1

MENU

2

1.0

3

RIT

BAND

0.5

2

1
SPEED

EDIT

RF GAIN

TAP: 10 HZ / 100 HZ
HOLD: 1 kHz

CLR

2.0

FILTER

DISP

TUNE

LAMP

POWER
ON
OFF

\

KEY /
PADDLEAF GAINO W N E R’S M A N U A L

ELECRAFT KX1
Ultra-Portable
CW Transceiver
Owner’s Manual
Revision E, May 21, 2010

Copyright  2010 Elecraft, Inc.
All Rights Reserved

Elecraft  www.elecraft.com

P.O. Box 69  Aptos, CA 95001-0069(831) 662-8345  Fax: (831) 662-0830

ELECRAFT

2

Table of Contents
INTRODUCTION .......................................................................................................................................................................................... 3
SPECIFICATIONS........................................................................................................................................................................................ 5
PREPARATION FOR ASSEMBLY .............................................................................................................................................................. 6
ASSEMBLY - PART I ................................................................................................................................................................................. 14
ALIGNMENT AND TEST - PART I ............................................................................................................................................................ 27
ASSEMBLY – PART II ............................................................................................................................................................................... 30
ALIGNMENT AND TEST - PART II ........................................................................................................................................................... 43
ASSEMBLY - PART III ............................................................................................................................................................................... 48
ALIGNMENT AND TEST - PART III .......................................................................................................................................................... 58
FINAL ASSEMBLY .................................................................................................................................................................................... 60
OPERATION .............................................................................................................................................................................................. 62
KX1 OPTIONS............................................................................................................................................................................................ 71
CIRCUIT DETAILS ..................................................................................................................................................................................... 72
PARTS LIST ............................................................................................................................................................................. APPENDIX ASCHEMATIC ............................................................................................................................................................................ APPENDIX BBLOCK DIAGRAM ................................................................................................................................................................... APPENDIX CPHOTOGRAPHS...................................................................................................................................................................... APPENDIX D
TROUBLESHOOTING ............................................................................................................................................................. APPENDIX EPARTS PLACEMENT DRAWINGS ......................................................................................................................................... APPENDIX FQUICK REFERENCE ...............................................................................................................................................................APPENDIX GELECRAFT

3

Introduction
The Elecraft KX1 is a compact, multi-band CW transceiver
optimized for backpacking and travel use. With internal battery,internal automatic antenna tuner, log-book lamp, and plug-in keyer
paddle, it offers a high level of integration.
Unlike most transceivers, the KX1’s controls are located on the topof the cabinet, and the keyer paddle attaches at the front. This “trailfriendly” format is ideal for hand-held or lap-top operation, e.g.
when sitting on the ground, using a camp chair, reclining, or evenstanding. The KX1 is also at home on a table or desk, providing an
optimal display viewing angle without the need for a tilt stand. The
unique plug-in keyer paddle is both physically reversible for right- or
left-handed use.
The transceiver covers the full 40 and 20 meter bands, and optionally
80 and 30 meters. The VFO is based on a DDS (direct digitalsynthesis) IC, so it can also tune well outside each band, covering
many popular SWL band segments. A variable bandwidth crystal
filter permits reception of SSB and AM as well as CW, facilitating
cross-mode contacts and broadcast reception.
The KX1’s internal six-cell battery pack can be changed in seconds
with the removal of two thumb screws. The battery provides 1 to 2
watts power output, which represents a good tradeoff between
battery life and communications efficiency. An external 12 V supply
increases output to about 4 watts. Low receive-mode current drain(35 mA typ.) results in battery life of 20 hours or more. The lowbattery warning threshold can be adjusted to match the battery typeused.

The KX1 uses a 3-digit LED display that is physically rugged andextremely efficient. It requires just 1 to 2 milliamps total current inmoderate lighting conditions, and about 10 mA at its brightest setting.
The operator can optionally configure the display to turn off 5 to 60
seconds after any front-panel control has been used. Operation without
the display is possible if the CW feedback feature is turned on (audio
Morse code). This provides audible announcement for the VFO dial,menu text, and all controls.
Additional operating features include instant band selection, nine
frequency memories, three VFO tuning rates, receive incremental tuning(RIT), USB/LSB receive on all bands, and an S-meter display mode.
The built-in keyer offers Iambic modes A and B and two message
buffers. In an emergency, two of the front panel switches can be
configured for use as a manual key or keyer paddle.
Despite its compact size and many built-in accessories, the KX1 is easy
to build. The basic unit consists of a single printed circuit board, with nosurface mount components to install (the three surface mount parts used
are pre-installed). Assembly and test are completed in phases to simplify
any needed troubleshooting, and only a few alignment steps are
required.
We’d like to thank you for choosing the KX1 transceiver, and hope itmeets your expectations for ultra-lightweight portable operation.
Wayne Burdick, N6KR
Eric Swartz, WA6HHQ

4ELECRAFT

Customer Service Information
Elecraft's 1-Year Limited Warranty

Technical AssistanceIf you have difficulty with kit construction, operation, or
troubleshooting, we’re here to help. You may be able to save time by
first consulting our web site, www.elecraft.com, or by posting yourquestion on the Elecraft e-mail forum, elecraft@mailman.qth.net.
Telephone assistance is available from 9 A.M. to 5 P.M. Pacific time
(weekdays only) at 831-662-8345. You can also send e-mail tosupport@elecraft.com. Please use e-mail, rather than call, whenpossible since this gives us a written record of the details of yourproblem.

Repair Service
If necessary, you may return your completed kit to us for repair.
Contact Elecraft before mailing your kit to obtain the repair
shipping address, as well as information on repair fees. (Kits thathave been soldered using acid core solder, water-soluble flux solder,or other corrosive or conductive fluxes or solvents cannot be
accepted for repair–see Warranty.)
The following information should be provided to expedite repair:your name, address, and phone number; your e-mail address (ifapplicable); and a complete description of the problem.
Shipping: First, seal the unit in a plastic bag to protect the finish
from dust and abrasion. Use a sturdy packing carton with 3" or moreof foam or shredded paper on all sides. Seal the package withreinforced tape. (Neither Elecraft nor the carrier will accept liability
for damage due to improper packaging.) Cover the "to" address labelwith clear tape.

This warranty is effective as of the date of first consumer purchase (or if shipped fromfactory, date product is shipped to customer). It covers both our kits and fully
assembled products. For kits, before requesting warranty service, you should fullycomplete 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 of order. Elecraft products transferred by thepurchaser to a third party, either by sale, gift or other method, who is not disclosed to
Elecraft at the time of original order, are not covered by this warranty. If the Elecraft
product is being bought indirectly for a third party, the third party's name and address
must be provided to Elecraft at time of order to insure warranty coverage.

What is covered: During the first year after date of purchase, Elecraft will replace
defective or missing parts free of charge (post-paid). We will also correct any
malfunction to kits or assembled units caused by defective parts and materials.
Purchaser pays inbound shipping to Elecraft for warranty repair, Elecraft will pay
shipping to return the repaired equipment to you by UPS ground service or equivalent
to the continental USA and Canada. Alaska, Hawaii and outside U.S. and Canada
actual return shipping cost paid by 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, or builder modifications; or any performance malfunctions involving nonElecraft 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 is reimbursement for loss of use, inconvenience, customer assemblyor alignment time, or cost of unauthorized service.
Limitation of incidental or consequential damages: This warranty does notextend to non-Elecraft equipment or components 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.

ELECRAFT

5

Specifications
GeneralSize (H x W x D)
CabinetOverall
WeightSupply voltage
Current drain
Receive

Transmit

audio CW feedback on keypress
Transmitter
1.2 x 5.3 x 3.0" (3 x 13.5 x 8 cm)
1.4 x 5.8 x 3.0" (3.5 x 15 x 8 cm)
9 oz. (0.25 kg), excluding options
7-14 V (8 V min. recommended)

Max. power output (approx.)

Spurious content-40 dB @ 3 to 4 W

35 mA typ., 40 mA max (headphones,
LED display timed out, 30-m or
30/80-m option installed)
300-700 mA (varies with supply
voltage and power output setting)Load tolerance

2:1 or better SWR recommended

Sidetone pitch

500-650 Hz in 10 Hz steps

Keyer

8-50 WPM; Iambic modes A and B;
2 message buffers; auto-repeat

Bands covered (MHz)1
Receive
5.0-9.5 and 12.0-16.5 MHz
Transmit
7.000 to 7.300, and 14.000 to 4.350
MHz; spurious content at 3 to 4 w, 2nd
harmonic -40 dB typ. with LPF
adjustment (see page 59)
Frequency control
DDS with 50 MHz crystal reference
VFO drift< 50 Hz per hour after 5-minutewarm-up at 25° C
Display
3-digit LED w/bargraph mode;
1

KXB30 option adds 8.0-12.5 MHz receive and 10.1-10.15 MHz transmit.
The KXB3080 option covers the same range as the KXB30 and adds 1.5-5.5
MHz receive and 3.5-4.0 MHz transmit. Adding either module also greatly
improves sensitivity in the 49-meter band (5.9-6.4 MHz).

9 V supply

1.5-2 W

12 V supply

3-4 W

ReceiverSensitivity
I.F.

Approx. 0.2 µV for 10 dB (S+N)/N
4.915 MHz, single conversion

Selectivity

3-pole variable-bandwidth crystal
filter, approx. 300-2000 Hz

Audio output

0.1 watt into 8-ohm load;stereo plug required

ELECRAFT

6

Preparation for Assembly
Overview of the KX1
The KX1 chassis consists of a top and bottom cover (Figure 1). Allcomponents, including controls and connectors, are mounted on asingle printed circuit board (PCB). Only three surface-mountcomponents are required, and these are pre-mounted to the board.
The top cover is also the front panel. The controls face upward forconvenient operation. The printed circuit board mounts directly behindthe front panel.
The automatic antenna tuner option (KXAT1) plugs into the bottom of
the main PC board at J6, J7 and J8. The optional keyer paddle(KXPD1) plugs into the Keyer/Paddle jack, J3, at the front edge of the
top cover.
The bottom cover is held in place by two thumbscrews. Two three-cell
AA battery sockets are attached to the bottom cover and are wired inseries to form a six-cell pack. The battery voltage is 7.2 or 9 V
depending on the battery type.
Appendix D provides close-up views of the top and bottom of theassembled PC board.

Figure 1. KX1 Overview.

ELECRAFT

7

Unpacking and Inventory
Preventing Electro-Static Discharge Damage

Inventory

Problems caused by Electro-Static Discharge (ESD) may be very
difficult to troubleshoot because damaged components may still
operate somewhat rather than fail completely. We strongly recommend
you take the following anti-static precautions (listed in order ofimportance) to avoid trouble:

We recommend that you do a complete inventory, using the parts lists
in Appendix A.

Leave ESD-sensitive parts in their anti-static packaging until
you install them. The packaging may be a special plastic bagor the component’s leads may be inserted in conductive foam.
Parts which are especially ESD-sensitive are identified in theparts list and in the assembly procedures.



Wear a conductive wrist strap with a series 1 megohm
resistor. If you do not have a wrist strap, touch a groundbriefly before touching any sensitive parts to discharge yourbody. Do this frequently while you are working. You cancollect a destructive static charge on your body just sitting at
the work bench. DO NOT attach a ground directly to
yourself as this poses a serious shock hazard.

Make sure your soldering iron is ESD-safe and has agrounded tip



Use a grounded anti-static mat on your work bench.

i

DO NOT HANDLE PARTS OR CIRCUIT BOARDSWITHOUT ANTI-STATIC PROTECTION (see Preventing
Electro-Static Discharge Damage above). Do not remove the black
foam from the leads of any parts. This foam is further protection
against static damage.
Many components are inside small envelopes and bags. Open them
one at a time, and return all of the parts to the envelope before opening
another. Be careful to avoid mixing parts and putting them in thewrong bags or envelopes.

ELECRAFT

8

Identifying Common Resistors and RF Chokes
The color bands that indicate the value of each resistor are shown in
the text to help you identify each part. However, it's helpful tofamiliarize yourself with the color code. The color-code chart (seeFigure 2) shows how to read the four color bands on 5% resistors. For
example, a 1,500 ohm (1.5 k) 5% resistor has color bands BROWN,
GREEN, RED and GOLD.
1% resistors are similar, but use five bands: three significant digits, amultiplier instead of a gold or silver tolerance band, and a fifth and toindicate the tolerance. Since the bands usually fill the length of theresistor body, the fifth band is wider to indicate that the value should
be read starting at the other end.
For example, the first four bands on a 1.50 k, 1% resistor are
BROWN, GREEN, BLACK, BROWN. The multiplier value is 1
rather than 2 in this case because of the third significant digit.
If in doubt about a resistor’s value, use a DMM. It may be difficult to
see the colors on some resistors. Do not be concerned with minor
deviations of your DMM reading from the expected value. Typicalerrors on most DMMs and the tolerances of the resistors normally
produce readings that are slightly different from the value indicated by
the color bands.
RF chokes and other small molded inductors look very much like shortresistors. They have color bands that represent the same numericvalues as resistors but because the inductors are short, it may not be
obvious how to read them. In general the multiplier or tolerance bands
are closer to the end than the first digit, just the opposite of the way a
resistor. On small inductors the color bands may be centered on thebody.

If you sort out the inductors before starting assembly, you will be able
to positively identify each inductor from the color bands listed in theParts List.

USED ON 1%
RESISTORS(SEE TEXT)FIRST DIGITSECOND DIGITTOLERANCE:
GOLD = 5%
SILVER = 10%

MULTIPLIER

COLOR
Black
Brown
Red
OrangeYellow
GreenBlue
VioletGray
White
Silver
Gold

DIGIT
0
1
2
3
4
5
6
7
8
9
-

MULTIPLIER
X1
X 10
X 100
X 10K
X 10K
X 100K
X 1M
X 0.01
X 0.1

Figure 2. Resistor Color Codes.

ELECRAFT

9

Identifying Resistor Packs
Resistor packs combine a number of resistors in one component withmultiple leads. They may be in-line packages with 6 or 10 leads in arow or they may be in 16-pin dual in-line pin (DIP) packages similar
to many integrated circuits.
Like integrated circuits, pin 1 of each component is identified by a dot
near it. Some resistor packs are symmetrical. That is, they can beinstalled either way. However, some are not. ALWAYS follow the
instructions and orient the resistor pack exactly described in theprocedure.
The value of the resistor pack is indicated in the last three digits shownon the package. The numbering scheme is similar to capacitors. The
first two digits indicate the first and second most significant digits andthe third digit is a multiplier. For example, “...391” indicates 390 ohms
and “...104” indicates 100,000 ohms (100K).

Identifying Capacitors
Capacitors are identified by their value and the spacing of their leads.
Small-value fixed capacitors are usually marked with one, two, or
three digits and no decimal point. If one or two digits are used, that isthe value in picofarads (pF). If there are three digits, the third digit is amultiplier. For example, a capacitor marked "151" would be 150 pF(15 with a multiplier of 101). Similarly, "330" would be 33 pF, and"102" would be 1000 pF (or .001 µF). Exceptions are described
specifically in the text and parts list.

Fixed capacitors with values of 1000 pF or higher often use a decimal
point in the value, such as .001, .047, or 2.2. This is the value inmicrofarads (µF). (1 µF is equal to 1,000,000 pF.)
The lead spacing is noted in the Parts Lists for most capacitors. If two
different types of capacitors have the same lead spacing will indicate
which one to use. When lead spacing is important, both the value andthe lead spacing is shown in the assembly procedure. For example,“LS 0.1” means that the lead spacing is 0.1 inch (2.5 mm).

Identifying Toroid Cores
Several toroidal inductors are used in the KX1. It is important to use
the correct type of core. This can be determined from the color andsize. Two types of cores are used in the KX1: Iron powder cores andferrite cores. If you mix them up, your KX1 will not operate properly.
The iron powder cores used are type T37-6. The T identifies an ironpowder core. The number following the T specifies the outside
diameter in hundredths of an inch, in this case 0.37 inches (9.4 mm).
The suffix (-6) refers to a specific mix of iron powder. You cannot tellwhat mix of iron power is used by looking at the core, so they are
painted with specific colors. The -6 cores are painted yellow.
Ferrite cores are indicated in the parts list by the letters FT in the partnumber. The KX1 uses FT37-6 cores. Like the iron powder cores, the37 refers to the outside diameter. The -46 identifies the type of ferrite
used. These cores are not painted. They are dark grey.

ELECRAFT

10

Tools
You will need the following tools to build this kit:Fine-tip temperature-controlled ESD-safe soldering station
with 700 to 800F tip (370-430C). Recommend a spade tip
approx. 0.05” (1.3 mm) wide. Do not use a high-wattage ironor soldering gun since this can damage pads, traces, or theparts themselves.
IC-grade, small-diameter (.031”) solder (Kester #44 orequivalent).

i

DO NOT use acid-core solder, water-soluble flux solder,
additional flux or solvents of any kind. Use of any of these willvoid your warranty.

Desoldering tools and supplies are invaluable if you make any
modifications or need to do any repairs. Narrow solder wick or
a good vacuum desoldering tool such as the Soldapullt®
model DS017LS are recommended. See Soldering and
Desoldering, on page 11 for more information.



Screwdrivers: A small #2 Phillips, a small flat-blade forslotted screws and a very small flat-blade (about 0.1 in or 2.5
mm wide) with an insulated handle to adjust the trimmer caps.

Needle-nose pliers.



Small-point diagonal cutters. Flush-cutting type is required(Xcelite MS54-5J or equivalent).



Digital Multimeter (DMM) for voltage checks and confirming
resistor values. A DMM with capacitance measurement
capability is desirable, but not required.



50-ohm dummy load capable of handling 5 watts, minimum.

Magnifying glass or visor.

We strongly recommend that you use a conductive wrist strap andanti-static mat during assembly. These items are available at very low
cost from Jameco, Mouser, and other electronics suppliers.
Refer to www.elecraft.com for tool sources and solder
recommendations.

ELECRAFT

11

Soldering and Desolderingi

Use adequate ventilation when soldering; avoid
inhaling smoke or fumes. Always wash your hands after
handling solder, as lead residue is highly toxic.

Solder Recommendations
We recommend small-diameter (.02 to .03") rosin-core solder, similar
to Kester type 44. Solder with 2% silver is used by some builders andwill work equally well.
If you use a minimum of solder, there will be no need to clean PC
boards. The use of acid-core solder, water-soluble flux solder, or any
corrosive or conductive flux or solvent is likely to damage components
and/or PC boards.

Soldering
When applying solder, use the minimum amount required to surroundthe component lead and make good contact with its printed-circuit pad.
You don't need a "fillet" (build-up) of solder.
To provide a good connection, the solder must flow onto both thecomponent lead and its PC board pad. To ensure that both will beheated at the same time, the tip of the iron should contact both thecomponent lead and the PC board pad before solder is applied.

Solder joints should be clean and shiny. If a joint appears dull or has
fine cracks, it is probably cold. Cold solder joints should be cleaned
and re-soldered. First, use solder wick (desoldering braid) to remove
the old solder. Then apply fresh solder. If you have many cold solder
joints, it probably indicates that your soldering iron temperature is too
low, or that the tip or solder itself is defective.
New soldering iron tips must be tinned before they’re used. Allow theiron to warm up completely, then apply solder and allow it to coat theentire tip. After a few minutes, wipe off the excess solder. Use asponge for wiping the iron tip, and clean the sponge often.

ELECRAFT

12

Desoldering
The printed circuit boards used in the kit are double-sided, meaningthat they have circuitry on both sides. The component mounting holes
are plated-through to complete electrical connections between the twosides.
Removing components from double-sided boards can be difficult,since you must get all of the solder back out of the hole before a leadcan be removed. To do this, you'll need solder wick (desoldering
braid) and/or a vacuum desoldering tool. It also takes some practice. A
number of suggestions are provided below.
The best strategy for avoiding de-soldering is to place allcomponents properly the first time. Double-check values andorientations, and avoid damaging parts via ESD.

When removing components:
Don't pull a lead or pin out of a hole unless the solder has been
removed, or you are applying heat. Otherwise, you can literally
pull out the plating on the plated-through hole.

Limit soldering iron contact to a few seconds at a time.



Use small-size solder-wick, about 0.1" or 2.5 mm wide. Use thewick on both the top and bottom pads when possible. This helps
get all of the solder out of the hole.



If you use a vacuum desoldering tool (solder sucker), use a large
unit. Small solder suckers are not very effective.

The safest way to remove ICs and other components with morethan 3 leads is to clip all of the pins at the body of the device first,
then remove all of the pins individually. You may damage pads
and traces by trying to remove such components intact.



Invest in a PC board vice with a heavy base if possible. This
makes parts removal easier because it frees up both hands.

If in doubt about a particular repair, ask for advice from Elecraft orfrom someone else with PCB repair experience.

ELECRAFT

13

Assembly Notes
Each step in the assembly process is accompanied by a check-box:

As you may have noticed already, the symbol below is used to alert
you to important information:i

Do not skip any steps. You may adversely affect both theperformance and appearance of the kit by using the wrong
assembly order.

Installing Parts
Follow the instructions carefully about the position of parts. Many
parts must be positioned exactly as instructed or they may strike thecase or other components when the KX1 is assembled.
The value and corresponding color codes are shown for all resistors
and inductors that may have them. In some cases the value may be
stamped on the component instead of the color code.
Before beginning assembly, you should review the photographs inAppendix D to see what the completed PC boards look like. You'll
also find front and back views of each PC board in the Parts Placement
Drawings, Appendix F.

IC Sockets
Only one integrated circuit is mounted in a socket. Do not use a
different type of socket. The one supplied is a low-profile socket thatprovides just enough room for the case to fit together.
Do not use sockets on any ICs other than the one provided. Mount theother ICs directly on the board as instructed. Sockets will not allow thecover to close. Also sockets in RF may cause improper circuit
operation due to increased lead inductance and capacitance.

ELECRAFT

14

Assembly - Part I
In Part I, the control, display, and audio stages will be assembled andtested. Later sections cover receiver (Part II) and transmitter (Part III)assembly and test.

i

BEFORE YOU START:

1. WEAR A GROUNDED WRIST STRAP or groundyourself briefly before touching components. You candischarge static by frequently touching an unpainted,
grounded metal surface.

If you haven’t done so already, open the bag of components
labeled KX1 MAIN BAG and sort the parts into groups. Many of thecomponents will be in small paper envelopes. Do not mingle thecontents of one envelope with another. As you are instructed to locate
particular components, use the photographs in the KX1 PCB parts listin Appendix A to help identify them.

i

The components pre-installed on the circuit board are
extremely static-sensitive. Wear a wrist strap or ground yourself
before handling the board.

2. WEAR EYE PROTECTION before trimming any leads.
3. WASH YOUR HANDS after handling solder. Solder is a
toxic substance.
4. PROVIDE VENTILATION and avoid inhaling the fumes
produced by soldering.

Position the circuit board on your bench so that KX1 is visible in
the upper left corner. This is the side of the board that will be directly
under the front panel when the transceiver is completed. This side will
be referred to the as the top face of the board throughout the assembly
procedure. Components will be installed on both sides of the board.
Turn the circuit board over so the bottom is facing up and orient
it so the outline for J1 is in the upper right corner. Find the outline forresistor R8 next to the outline for J1.

ELECRAFT

15

Bend the leads of resistor R8, 6.8k (blu-gry-red), 1/4 watt, atright angles close to the body. Insert the leads in the solder pad holes,
and bend them out on a 45-degree angle on the opposite side of theboard to hold the resistor in place.

Bend the leads of resistor R28, 1.8k (brn-gry-red), 1/4 watt, to fit
in the holes indicated on the board. Note that the leads should NOT bebent close to the body of the resistor like you did for R8. Fit the leads
so the body of the resistor sits against the board within the outline,
then bend them outward at about a 45 degree angle to hold the resistor
in place.

iComponents MUST be tight against the board or the casemay not close properly during final assembly. This is especiallytrue of components on the bottom of the board where there is very
little clearance between the board and the battery packs.

Solder the leads to R28 and trim them flush with the board.

i

Check the position of the resistor to ensure it is centered in theprinted outline and flush against the board as shown in Figure 3.
Solder and trim the leads.
ENSURE MARKINGS AGREE WITH
INSTRUCTIONS IN TEXTBODY OF PARTAGAINST THE BOARD

From this point forward, instructions to “install” acomponent mean to position it within its outline against the board,solder, and trim the leads flush on the opposite side.
Locate the two 200 ohm (red-blk-brn)1/8 watt fixed resistors, R6
and R7. They are about half the size of the 1/4 watt resistors you justinstalled.
Install the 1/8 watt resistors in the spaces shown just to the left of
R8 near the top of the board:

SOLDER & TRIM LEADS FLUSH

Figure 3. Installing Fixed Resistors.
Locate the printed outline for R28 on the back of the board. It is
about 3/4” (2 cm) down from the top edge near the center.

i_

R6, 200 ohms (red-blk-brn), 1/8 watt.

_

R7, 200 ohms (red-blk-brn), 1/8 watt.

Components may be soldered one at a time or in groups.
Leads can be trimmed either before or after soldering.

ELECRAFT

16

i

Save the longer clipped component leads. Several of themwill be needed for grounding wires and a jumper.
Install the following 1/4 watt resistors on the bottom side of theboard. Their locations are in the lower right quadrant of the board
when it is oriented the so outline for J1 is in the upper right corner.
_

R16, 1k (brn-blk-red).

_

R17 ,1k (brn-blk-red).

_

R22, 300 ohms (org-blk-brn).

_

R23, 470 ohms (yel-vio-brn).

Locate resistor pack RP5, 100 k ohm (104). RP5 is a ten-pin inline package whose number on the side ends in “104” (see Figure 4).
If you are in doubt about the value, use your DMM to verify that theresistance between adjacent pins is 100k ohms. Note the dot at one end
indicating pin 1.

Turn the board over (top face up) and orient it so that the KX1
lettering is in the upper left corner and the notch is on the lower edge.
Install the following 1/4 watt resistors about 3/4” (2 cm) to the leftof the notch and about 3/4” (2 cm) up from the lower edge of theboard:_

R12, 6.8k (blu-gry-red).

_R13, 22k (red-red-org).

Figure 4. Installing Resistor Packs.
Find the outline for RP5 on the top of the circuit board. With theboard face up so that KX1 is in the upper left corner, the outline forRP5 is just to the left and above the notch at the center of the lower
edge of the board.

ELECRAFT
Insert RP5 with Pin 1 of the pack in the round solder pad. The
round pad is farthest from the edge of the board.

i

Be careful to orient the resistor packs so the dot next to
Pin 1 on the pack is at the round solder pad on the board. Oncesoldered in place, it is almost impossible to remove the packwithout destroying it.
Wet your soldering iron with a small amount of solder, and touch
it to one of the pins to tack-solder it in place.

17

Locate resistor pack RP1, 390 ohms (391). RP1 is in a 16-pin DIP
package that looks much like an integrated circuit. The resistanceelements run across the package (e.g. pin 1 connects to 9 through 390ohms).
Test fit RP1 between RP2 and RP3 and just below the outline forDS1 on the circuit board. It is normal for the pins of a DIP package tobe slightly flared so they do not easily fit into the solder pad holes. If
necessary, place RP1 so that an entire row of pins is against a smoothsurface and straighten the pins as shown in
Figure 5.

Check the position of RP5 to verify that the pins at both ends areinserted as far as they will go into the board as shown in Figure 4, thensolder and trim all ten leads.
Follow the same procedure to install six-pin resistor pack RP2, 1K(102) above and to the left of RP5. Pin 1 goes at the top pointing
toward the printed outline for C51.
Install ten-pin resistor pack RP4, 10k (103) below U2 in the top
left quadrant of the board. Pin 1 goes to the left, pointing toward theoutline for RP3.
Install ten-pin resistor pack RP3, 10k (103) to the left of RP4. Pin
1 of RP3 is at the top, nearest the end of RP4.

FLAREDPRESS ANDROCK TOSTRAIGHTENSTRAIGHT

Figure 5. Straightening IC Pins.
Place RP1 on the circuit board with pin 1, indicated by a dot on
top of RP1, in the round solder pad. Be sure it is seated all the way so
the shoulders on the pins are against the board. Solder and trim all 16
pins.

ELECRAFT

18

Turn the board face up so KX1 is in the upper left corner. Locate
the printed outlines for diodes D2 and D3 near the center of the leftedge of the board.
Locate diodes D2 and D3 (1N5817). Note that there is a band on
one end of the diode body.

i

All diodes MUST be installed with the banded end of thediode over the band on the circuit board.
Install the following diodes:_

D2 (1N5817)_

D3 (1N5817)

With the board face up (KX1 in the upper left corner) position the
28-pin socket in the space provided for U1 in the lower left quadrantof the board. The outline has (SOCKET) inside of it.

i

DO NOT TRIM the 28-pin socket pins before or after
soldering. These pins are hollow and form the lower part of thesocket for the IC pins.

i

Do not substitute a different socket for the one provided.
The very low profile of the supplied socket is required for the caseto fit together during final assembly.
Orient the socket so the notch at one end is toward the left edge ofthe board, aligned with the notch in the printed outline.
Hold the socket against the circuit board and tack-solder pins at
opposite corners of the socket.

i

Do not overheat the socket pins. Too much heat will melt
the plastic socket. Use only enough solder to make a good joint.
Check to ensure that the socket is pressed against the circuit board
at both ends. If necessary, reheat the pins at each end and press downon the socket so it rests directly against the board.
Solder all 28 pins. Double-check your work and inspect each pin.
Use a magnifier if necessary. If a pin is missed or poorly soldered, it
may make contact during initial testing, but become intermittent later.
Such intermittents can be very difficult to troubleshoot. Remember;do not trim the socket pins!

ELECRAFT
Turn the board face down so the printed outline for power
connector jack J1 is in the upper right corner.
Locate the printed outline for C39 to the left of the outline for J1
on the board.
Test fit a .1 µF (104) capacitor in the solder pad holes for C39.
Position the capacitor so that about 1/16” (1 mm) of lead shows above
the surface of the board. If necessary, gently straighten the leads using
long nosed pliers. Do not tug on the leads. Squeeze and bend themwith your pliers as needed.

19

Test fit a .1 µF (104) capacitor in the solder pad holes for C31.
Use a ruler to verify that the top of the capacitor is no more than 5/16”(7.9 mm) above the board. Normally these capacitors will be well
below that height limit but, if necessary, gently straighten the leads
using long nosed pliers so it will sit closer to the board and meet theheight requirement. While forming the leads, do not tug on them.
Squeeze and bend the leads with your pliers to straighten them.
Slight chipping of the epoxy around the leads will not harm thecapacitor.

Solder and trim the C39’s leads.
Bend C39 down against the board as shown in Figure 6.

Figure 7. Installing Fixed Capacitors.
Figure 6. Positioning C39 Against the PCB.
Locate the outline for capacitor C31 along the top edge of theboard just to the left of the outline for J1.

Solder and trim the leads on capacitor C31.

ELECRAFT

20

Following the same procedure, install capacitor C30, .01 µF (103)next to C31.

Install capacitor C5, .1 µF (104) below the socket for U1 near thebottom edge of the board.

Turn the board top face up so that KX1 is in the upper left corner.
In the following steps you will install several capacitors on the top ofside of the board. Be sure that the top of no capacitor is more than
5/16” (7.9 mm) above the board. Be especially careful of the larger
electrolytic capacitors (see Figure 8). Use a ruler as needed to checkthe height.

Install the following capacitors between the socket for U1 and thebottom edge of the board:_

C25, 27 pF (270)_

C24, 27 pF (270)Install the following capacitors to the right of resistor pack RP5:_

C32, .01 µF (103)_C33, .01 µF (103)Install capacitor C55, .01 µF (103) on the bottom edge of theboard about 1-1/4” (2 cm) to the right of resistor pack RP5.

Figure 8. Maximum Height of Capacitors on Top of Board.
Install capacitor C6, .01 µF (103) directly above diode D3 on theleft edge of the board.
Install capacitor C37, .01 µF (103) between D2 and resistor packRP3.
Install capacitor C12, .1 µF (104) between D2 and the socket
for U1.

Locate electrolytic capacitor C38 (10 µF, 35 v) and inspect theleads. One lead should be shorter than the other. The capacitor bodywill have a stripe and a minus sign (—) above the shorter lead.
Locate the printed outline for C38 to the left of RP3 on the top
face of the circuit board. Note that there are two solder pads for thecapacitor leads: one is round and one is square. A plus (+) symbol isprinted next to the square pad.

ELECRAFT
Insert electrolytic capacitor C38 (10 µF, 35 v) with the longer leadpassing through the square solder pad with the (+) symbol next to it
and the shorter lead through the round pad. Bend the leads to hold thecapacitor in place against the board.
Be sure that the capacitor is tight against the board and solder theleads. Use a ruler to verify that the top of the capacitor is no more than
5/16” (7.9 mm) above the board (see Figure 8). After soldering, trim
the leads flush with the bottom of the board.

i

All electrolytic capacitors MUST be installed with theirleads oriented to observe the polarity markings as describedabove.
Install electrolytic capacitor C10 (10 µF, 35 v) below resistor R13
at the bottom edge of the board. Observe the proper polarity as you
did for C38 above, and be sure the capacitor is no higher than
5/16” (7.9 mm) above the board.
Turn the board over so the bottom face is up and the outline for J1
is in the upper right corner.
Install electrolytic capacitor C7 (220 µF, 25 v) at the center of theboard near resistor R28. Be sure to observe the proper polarity as
you did above. Save one of the clipped leads to use in the following
steps.

21

Turn the board over so the top face is up and test-fit the lowprofile crystal in the space provided for X1 near the bottom edge
below the socket for U1. The crystal may be installed either way.
Note: The holes in the solder pads for X1 may be larger than necessary
to fit the leads. This is normal. It is to accommodate different styles ofleads on the crystals supplied with some kits.

i

Do NOT use more solder than necessary on the leads for
X1. Too much solder will wick through the holes and may cause ashort to the case of X1 underneath the crystal. The short is
impossible to see or correct without removing the crystal.
Spread X1’s leads as necessary to hold the crystal against theboard and solder one lead. Do not hold your iron on the lead morethan 2 or 3 seconds, maximum. Too much heat will ruin the
crystal.
Check to ensure that X1 is sitting directly against the board. If
necessary, reheat the soldered lead while pressing down on the crystal.
Solder the second lead to X1 and trim the leads flush.

ELECRAFT

22
Use a discarded component lead to ground the case of the crystal
as follows:_

Solder one end of the lead in the ground hole near the edge ofthe board to on the left side of the crystal.

_

Tin the top of the crystal nearest the lead with a small amountof solder. Keep the soldering time to 3 seconds or less to
avoid overheating the crystal. Allow the crystal to cool if you
need to apply heat more than once. It often helps to tin thecase more quickly if you lightly scrape the metal with a knife
or a screwdriver blade first.

_

Bend the ground lead so it lies flat against the top of thecrystal where it is tinned and solder it to the top of the metal
case.

Install white LED D1 as follows:_

Locate the flat side on D1’s flange.

_

Position D1 over the outline in the lower left corner of theboard with the flat side of the flange toward the corner of theboard.

_

Bend the leads so that when they are inserted through thesolder pads, D1 rests against the board as shown in Figure 9.
Note: This LED is provided to illuminate your note pad or log
while operating in the dark. The slight downward angle will
help direct the light down onto the table top.

_

Check to ensure that the flat side of the flange is toward thecorner of the board. D1 will not work if it is installedbackwards.

_

Solder and trim both leads.

_
Figure 9. Installing LED D1.
Turn the bottom face up with the outline for J1 in the upper rightcorner.
Position J1 (DC power connector) on the board so the three tabs
on the bottom of the jack fit through the slotted solder pads.
Solder one of the tabs and then check the position of the jack. It
must be centered within the printed outline on the board with theconnector opening parallel with the edge of the board. Be sure the jackis resting directly against the board. There must be no gap between
jack and the board. If necessary, reheat the soldered tab and adjust theposition of the jack.
When you are satisfied with the position of the jack, solder theremaining two tabs, then recheck the first tab be sure it is properly
soldered.

ELECRAFT
Test-fit two-pin plug P1 directly below J1. Orient P1 so thelocking ramp that sticks up alongside the pins is on the side farthestfrom J1 as shown on the printed outline on the board.
Place the shell for the mating jack over the pins of P1 to protect
your fingers and, while holding P1 directly against the board, solder
one of P1’s pins. Check the following. If necessary, reheat thesoldered pin and adjust P1.
_

P1 is oriented so the locking ramp is on the side
farthest from J1.

_

P1 is sitting vertically and resting flat against the board.

Solder the second pin of P1 to the board, then touch up the tacksoldered connection as needed to form a good joint.

i

If J3 is not aligned correctly as described in the next step,
the front cover will not fit during final assembly.
Install J3 at the center of the bottom edge of the board using thesame procedure to ensure it is square, inside the silk-screened outline
and flat against the board. Be certain you mount the jack on the
BOTTOM face of the board within the printed outline.

23

Turn the board over so the top face is up with KX1 in the upper
left corner.

i

Do not install caps on pushbutton switches S3, S4, and S5
until instructed to do so later in the assembly process. It is very
easy to damage the caps while soldering adjacent parts.
Position switch S5 on the board between RP2 and RP5. it may beoriented either way that places the four pins in the solder pad holes.
With all four pins in the solder pad holes, press down on S5 until theplastic bumps on the bottom of the switch body are touching theboard. Use a magnifier if necessary to be certain that the bumps on thebottom of the switch are against the board. Each of the four pins
should stick out through the solder pads on the bottom of the board
about 3/32” (2.4 mm).
When you are satisfied that the switch is firmly against the board,solder and trim all four terminals.
Install pushbutton switches S4 and S3 next to S5 using the sameprocedure.

ELECRAFT

24

Test fit slide switch S2 along the edge of the board next toelectrolytic capacitor C10. The switch can be oriented either way
around. Note that it rests on shoulders on the three terminals that
determine its height above the board.
Hold S2 vertical and against the shoulders on the tabs with yourfinger on the slide, and tack-solder the center pin to hold it in place.
Inspect the switch to be sure it is perfectly vertical and not tipped
to either side. If necessary, reheat the pin and adjust the switch’s
position.
When you are satisfied that the switch is perfectly straight, solder
the two end pins. Resolder the center pin last as needed to create agood joint.
Use the same procedure to install slide switch S1 to the left ofcrystal X1. S1 also may be mounted oriented either way.

i

Voltage regulators U8 and U9 are installed in the following
steps. These devices look very similar. Double check the markings
on each device to be sure you have the correct one before soldering
it in place.
Install U8 (78L05) next to pushbutton switch S5 as follows:_

Align the flat side of the device as shown by the printed
outline (see Figure 10).

_Insert the device into the solder pad holes until the top of thedevice is less than 5/16” (7.9 mm) above the board. Use aruler to confirm the height. If necessary, remove the device
and form the center lead to allow it to sit close enough to theboard.

_

Solder and trim all three leads.

FLATTENEDBACKORROUNDEDBACKPCB OUTLINE

Figure 10. Transistor Orientation Guide.

ELECRAFT

25

Install U9 (77L06) below RP5 on the lower edge of the board
using the same procedure that you used for U8 above. Be sure the topof the device is no more than 5/16” (7.9 mm) above the board.

Install 3-digit LED display DS1 as follows:_

Insert the 3-digit LED display in the space bounded byresistor packs RP1, RP2, RP3 and RP4. The pins on DS1
allow it to be inserted only one way.

Install transistor Q7 (2N4124). The position for Q7 is in the upper
right quadrant of the board, about 1” (2.5 cm) down from the top edge
and 1-3/4” (4.4 cm) from the right hand edge. Be certain the top of thetransistor is no more than 5/16” (7.9 mm) above the board.

_

Hold the display against the board and tack-solder pins at the
opposite corners.

_

Inspect the display carefully to ensure that it is firmly against
the board at both ends. If necessary, reheat one of the pins
and adjust the display. It is very important that the display befully seated and resting directly against the board at both
ends.

_

Solder and trim all 13 pins on the display.

Install 8-pin integrated circuit U3 (4427) in the space provided
near the right hand edge of the board, about 1-1/4” (3.3 cm) downfrom the top edge as follows:_

Test-fit U3 to see if the pins line up with the holes in thesolder pads on the board. If needed, straighten the pins likeyou did for resistor pack RP5 (see Figure 5).

_

Identify the end of U3 where pin 1 is located. It will have anotch, a dimple, or both at this end (see Figure 11).

_

Insert U3 into the solder pad holes with the notched, pin 1
end lined up with the notch on the printed outline.

_

Spread out the pins on the opposite corners to hold U3 inplace, then solder and trim all 8 pins.

Install encoder Z1 as follows. Z1 mounts to the left oftransistor Q7.
_

Test fit Z1 on the board. It will only go one way. The sidewith three terminals is nearest the top of the board.

_

Press down on Z1 until the small nubs at each corner rest
directly against the board. It is very important that Z1 be fully
seated against the board.

_

Solder two pins on opposite corners of the encoder, thenrecheck to ensure it is sitting against the board. If necessary,reheat the solder and press down on the encoder to position it.

_

Solder the two large tabs to the plated ring around the edge ofthe mounting holes. Apply only enough solder to make agood mechanical and electrical connection between the tab
and circuit board. Do NOT try to fill the holes with solder.

_

Solder and trim all five pins.

NOTCH

DIMPLE AT
PIN 1Figure 11. IC Alignment.

ELECRAFT

26

Visual Inspection

Resistance Checks

Verify correct orientation (banded end) of diodes D2 and D3,
using the parts placement drawing (Appendix F).

Make the resistance checks listed below with your DMM’s
negative (-) lead connected to the circuit board ground at the screw
hole just above capacitor C6.

Verify the correct orientation of each electrolytic capacitor. The
side of the capacitor with the strip and minus ( - ) sign must face awayfrom the + sign printed on the board.
Examine both sides of the PC board closely for solder bridges,
cold solder joints, or unsoldered components.

Test Point (+)

ResistanceU1 Pins 1, 3, 4, and 20>1k

U1 pins 8 and 19< 5 ohms

U1 all other pins> 10 k

U3 pin 3< 5 ohms

U3 all other pins> 10 k

D2 or D3 cathode(banded end), S1 On>1k

D2 or D3 cathode,S1 Off> 10 kELECRAFT

27

Alignment and Test - Part I
In this section you’ll become familiar with basic KX1 operation, while
testing the control and display functions.

iMicrocontroller U1 is extremely static-sensitive. Wear awrist strap or ground yourself before handling U1.
Remove microcontroller U1 from its conductive foam packing
and inspect the pins. The two rows of pins must be straight andparallel to each other to establish the proper pin spacing for insertion
into the socket. If necessary, straighten the pins as shown in Figure 5.

Press down very firmly on U1. If it is not seated as far as
possible into its socket, the pins may not make good contact.
Temporarily mount the VFO knob on the shaft of encoder Z1.
Align the set screw with the flat side of the encoder shaft and tighten it
using the Allen wrench supplied.

i

You may notice some side play in the encoder shaft. This isnormal in miniature shaft encoders with an integral pushbutton
switch.
Set slide switches S1 and S2 to the OFF position.

Identify the end of the IC where Pin 1 is located. It will have anotch, a dimple or both at this end (see Figure 11).

i

When U1 is pressed into its socket, you must be careful toavoid jamming its pins. Make sure all the pins are lined up withthe associated holes before pressing down on the IC. Watch thepins on both rows as you press down to be sure each pin goesstraight down into its socket hole and does not bend in under the
IC or outward alongside the socket. Realign each pin individuallywith its socket hole, if necessary.
Insert microcontroller U1 in its socket with pin 1 or the notched
end lined up with the notched end of the socket (the end closest to theedge of the board).

Connect an 8 to 14 VDC power supply to J1 with the positive (+)
lead to the center pin. A mating connector for J1 is supplied with thekit. If you use a power supply voltage of less than about 10.5 volts,
you may see a BAT LO message flashed on the LED during initialtests. This is because the BAT menu parameter is set to 10.0 volts bydefault. You can set the BAT parameter to a lower value to eliminate
the warning message.
Unwrap the cover and set it near the circuit board so you can see
the legends identifying the switches and their functions.

i

If any test or alignment step fails, refer to the
Troubleshooting section (Appendix E).

ELECRAFT

28

LED TestsiWhen testing the lamp in the following step, do NOT lookdirectly at the white LED. It is very bright.

Voltage Checks
Connect your DMM’s (-) probe to circuit board ground at thescrew hole next to capacitor C6. Use the (+) probe to check thefollowing DC voltages:

Switch S1 (LAMP) On and verify that D1 lights, then turn it Off.
Switch S2 (POWER) On. If you see or smell smoke, or acomponent feels hot to the touch, switch S2 Off and disconnect thepower source immediately. Locate the source of trouble before
proceeding.
You should now see either E10 or 00.0 on the 3-digit LED
display. E10 is an informational code that indicates that the EEPROM(configuration memory) on the microcontroller has been initialized todefault values. This message will appear only once, and can be clearedby tapping any of the three pushbutton switches. 00.0 is a portion of
the VFO frequency, which is set to 7100.00 kHz the first time you turnpower on. The display format will be described in a later step.

U1, pin 1: 5±0.25 Vdc_

U3 pin 6: 6±0.25 Vdc_

D2 anode: Supply voltage.

_

D2 cathode (banded end): supply voltage – 0.3 Vdc (approx).

Leave your DMM’s (-) probe connected to the circuit board
ground, and set your DMM for a 200 to 300 millivolt AC range.
Check the AC voltage at the following pins. A higher voltage thanshown may indicate a problem with one of the voltage regulators as
explained in the note below.

i

After a few seconds, the display turns off automatically if
you haven’t touched the VFO knob or pressed any switches. This
is intended to extend battery life. Moving the VFO knob or operating
one of the pushbutton switches will turn it on again. (The display timeout is programmable. This will be discussed in the next section.)

_

i

_

D2 anode: < 20 mV AC rms.

_

D2 cathode (banded end): <20 mV AC rms.

_

U1 pin 1: <20 mV AC rms.

_

U3 pin 6: <20 mV AC rms.

The 2.7 V and 6 V regulators used in the KX1 (U7 and U9,
respectively) are low-dropout types, which may oscillate if theirbypass capacitors are defective or are of the wrong value. If you
see high AC voltage at any of the points indicated above, verify
that electrolytic capacitors C7, C10, and C38 are installed in thecorrect orientation and that their leads are properly soldered. Ifthey are, you may be seeing a false AC voltage indication due tonoise or probe leakage; re-test using a different DMM.

ELECRAFT

29

The Tap/Hold Rule

Frequency Display and Band Change

Each of the push-button switches on the front panel has two functions,
one activated by a TAP (short press) and the other activated by a
HOLD (long press, about 1/2 second). The upper label on each switch
shows the TAP function (white lettering), and the lower label showsthe HOLD function (yellow lettering). To highlight this in the text, we
use two different typographical styles to identify switches: T AP and
HOLD.

The display shows three digits of the operating frequency. Which three
digits are shown depends on which tuning rate you’ve selected: 1 kHz,
100 Hz (default), or 10 Hz. At 7100.00 kHz, the three tuning rates
produce the following displays:

Accessing the Configuration Menu

7100.00

7100.00

7100.00

To select 1 kHz steps, press and hold the VFO knob (from now
on, we’ll indicate this as: hold 1 k H z ). Then try rotating the knob. No
decimal point is displayed at this step size.
To select 10 Hz or 100 Hz steps, tap the VFO knob (i.e., tap

Tap M E N U to enter the KX1’s configuration menu. You should
see LED on the display, which is the first menu entry (display
brightness setting and timeout period). Try rotating the VFO knob,
which scrolls through all 16 menu entries.

as you tap, and the decimal point moves accordingly.

Use the knob to return to the LED menu entry. Then holdE D I T to change the LED parameter. The display will change to L
followed by a number from 0 to 6.

display for your selected tuning rate.

Tap B AN D and R I T to change the display brightness. Settings of
2 or 3 are about right for indoor daytime use, 0 and 1 are suitable in
low lighting, and 5 or 6 in bright lighting.2

1 0 / 1 0 0 H z ). The tuning rate alternates between 10 and 100 Hz steps

You can check the MHz and kHz digits at any time by tapping
B AN D . For example, if the VFO frequency is 7100.00 kHz, tapping
B AN D will first show 7 , then 100, then return to the appropriate

To change bands, tap B AN D twice, quickly. This will trigger the
MHz-kHz display, in this case showing 14 then 100 (14100.00 kHz).
(Tapping or double-tapping B AN D also stores the present frequency
for the next power-up or band change.)

Rotate the VFO knob to select the desired LED timeout (5 to 60
seconds or INF for infinite, i.e. never times out. As you rotate theknob, the timeout period is flashed, e.g. t10 for 10 seconds. (Note:
When the LED times out, it will go blank. However, in very low
lighting or darkness, you may see a slight residual illumination.)Set the POWER switch to OFF.
Disconnect the power source from J1.
Remove the VFO knob and set it aside for reinstallation later.

Tap M E N U once to return to menu scroll mode, then tap it again
to return to the frequency display.

Wrap the cover and put it in a safe place until it is needed.

i2

CW feedback on switch-press can be used in lieu of the display. This is
described in the Operation section.

Leave microcontroller U1 in its socket during theremainder of the assembly process. Be sure to observe ESD
handling precautions at all times.

ELECRAFT

30

Assembly – Part II
In this section you will assemble and test the receiver circuits. The
transmitter circuits will be assembled in Part III.
Position the board face up with KX1 in the upper left corner.
Install R19, 1.8k (brn-gry-red), 1/4 watt to the right of RP5 near
the center of the board.
Turn the board over so that J1 is in the upper right corner. Install
the following 1/4 watt resistors in the lower left quadrant of the board.
Form the leads as required so the resistors lie directly against the board
within the printed outlines.
_

R21, 2.7k (red-vio-red)_

R14, 47 ohms (yel-vio-blk)_

R18, 3.3 megohm (org-org-grn)_

R29, 22k (red-red-org)_

R5, 4.7k (yel-vio-red)_

R20, 1k (brn-blk-red)_

R15, 1 megohm (brn-blk-grn)_

R25, 10 ohm (brn-blk-blk)

Open the envelope containing the seven molded inductors andsort them to be certain you know which is which before you install thefirst one. Compare the color codes you find on each inductor with thelist below. The color bands are very small. Use a magnifier as needed
to be sure of the colors.


L4: Micro (smaller) size, 2.2 µH (red-red-gold)

L5: Mini (larger) size, 5.6 µH (grn-blu-gold)

L6: Mini size, 6.8 µH (blu-gry-gold)

L7: Mini size, 4.7 µH (yel-vio-gold)

L10: Micro size, 33 µH (org-org-blk)

L8: Micro size, 18 µH (brn-gry-blk)

L9: Micro size, 100 µH (brn-blk-brn)i

Do not pull on the inductor leads while handling them.
They are more easily damaged than the resistors or capacitors.
Turn the board so the bottom face is up with jack J1 in the upper
right corner.

ELECRAFT
Install the following inductors below R6 and R7 in the upper rightquadrant.
_

L4, micro (smaller) size, 2.2 µH (red-red-gold)_

L5, mini size, 5.6 µH (grn-blu-gold). L5 may be larger thanthe outline. Bend the leads to fit into the pads with the bodyof L5 pressed to one side against the board. Do not space L5
above the board or it may strike other components when theK3 is assembled.

Turn the board face up with KX1 in the upper left corner.
Install the following inductors to the left of U3 on the right side of
the board.
_

L7, mini (larger) size, 4.7 µH (yel-vio-gold)_

L6, mini (larger) size, 6.8 µH (blu-gry-gold). If you have the
KXB3080 module to install, mount L6 on the bottom of the
PC board as shown in the KXB3080 module instructions. If
the lead spacing on L6 is larger than the hole spacing in theboard, bend the leads back under L6 to fit in the holes.

31i

In the next step you will install a diode which must be
oriented in the proper direction. Be certain to align the banded
end of the diode over the band on the circuit board.
Install diode D4 (1N4148) on the lower edge of the board to theright of L9.
Install varactor D5 (1SV149) as follows. When you are finishedthe top of the varactor must no be more than 5/16” (7.9 mm) above theboard.
_

Locate the outline for D5 on the board. It is near the center ofthe board immediately to the right of resistor pack RP5.

_

Orient the varactor according to the printed outline on theboard. The varactor may have a beveled back instead of arounded back as shown on the board (See Figure 10).

_Insert the varactor leads in the solder pad holes. The varactor
has a third lead that has been clipped close to the body. Spacethe varactor up off of the board slightly to ensure this leaddoes not short to the board.

_

Solder one lead, then check to ensure that the top of thevaractor is no more than 5/16” (7.9 mm) above the board. If
necessary, reheat the joint while adjusting the height of thevaractor.

_

Solder the second lead and trim both leads.

Install the following inductors below R19 near the center of theboard.
_

L10, micro size, 33 µH (org-org-blk). L10 may be larger thanthe outline. Bend the leads to fit into the pads with the bodyof L10 pressed to one side against the board. Do not space
L10 above the board or it may strike other components when
the KX1 is assembled.

_

L8, micro size, 18 µH (brn-gry-blk)_

L9, micro size, 100 µH (brn-blk-brn)

Follow the same procedure to install varactor D6 (1SV149). D6
is located above D5.

ELECRAFT

32

i

In the following steps you may be installing some
capacitors with leads closer together than the hole spacing in thecircuit board. Form the leads of these capacitors as shown in
Figure 12. Be sure the top of the capacitor is no higher than 5/16”(7.9 mm) above the board (see Figure 7).

Install capacitor C2, 27 pF (270) between capacitor C55 anddiode D4 on the lower edge of the board.
Install capacitor C21, .1 µF (104) at the lower right-hand cornerof the board.
Install the following capacitors between the printed outlines forpotentiometers R2 and R3 in the lower right quadrant of the board.

Figure 12. Forming Capacitor Leads.
Install the following capacitors above and to the right of the
3-digit LED display.
_

C50, 39 pF (39 or 390), lead spacing (LS) 0.2”_

C51, 100 pF (101), LS 0.2”_

C52, 22 pF (220)Install capacitor C16, .1 µF (104) between varactors D5 and D6.
Install capacitor C4, 27 pF (270) between molded inductors L8
and L10.
Install capacitor C8, .1 µF (104) directly above molded
inductor L9.

_

C17, .1 µF (104)_

C18, .1 µF (104)_

C19, .022 µF (223), LS 0.2”

Install capacitor C22, .01 µF (103) on the right hand edge of theboard above the printed outline for J4.
Install capacitor C27, 150 pf (151) directly above L6 in the upper
right hand quadrant of the board.
Install the following capacitors in the upper right quadrant of theboard.
_

C47, 220 pF (221) in the upper right corner of the board.

_

C54, 56 pF (56), to the left of C47.

_

C49, 1000 pF (102) below C54.

_

C48, 1000 pF (102) next to C49_

C46, 470 pF (471) next to C54

ELECRAFT
Locate C45, 68 pF (68 or 680), LS 0.2. Be sure that you do notconfuse this capacitor with C56, also 68 pF but with 0.1” lead spacing,that has not been installed yet. Note: C45 may be a much larger disctype, which would not fit in the location for C56. But if both are small,you’ll need to go by the lead spacing.
Install capacitor C45 to the left of C46 in the upper right quadrantof the board.
Install capacitor C26, 120 pF (121) pillow-style disc ceramic,
about 1/2” (1.3 cm) below C45. Be careful not to put this capacitor
in the space for C44. When C26 is installed, the space for C44
between C26 and C45 should be empty.
Test fit capacitor C1, 4.7 pF (4.7) pillow-style disc ceramic, next
to the lower right corner of the encoder. The bottom of the roundcapacitor body should touch the board. If the ceramic coating on theleads runs down too far to allow it to sit against the board, remove theexcess by squeezing the coating with long-nose pliers. It will crumble
and can be scraped away from the lead.
Install capacitor C1, 4.7 pF (4.7) making sure the bottom of theround body is touching the board.

33i

The following capacitors must be mounted closer to theboard than the others. They are installed in the area that lies
beneath the optional KXB30 30 meter or KXB3080 30 and 80
meter module. The KXB30 or KXB3080 module will not fit if thesecapacitors sit too high above the board.
The capacitors installed in this step must be closer to the board
than any of the previous parts you have installed. After installation,these capacitors must not exceed 5/32” (3.9 mm) in height.
_

C11, .1 µF (104) to the right of molded inductor L10.

_

C13, 56 pF (56) to the right of C11.

_

Use a ruler to verify that the above capacitors are no higher
than 5/32” (3.9 mm) above the board.

On the bottom of the board, ensure L5 (installed earlier) isagainst the board, or it may strike other components when the KX1 isassembled.

ELECRAFT

34

Turn the board over so jack J1 is in the upper right corner andlocate the printed outline for C15 just to the left of electrolytic
capacitor C7 at the center of the board.
Directly above the location for C15 is one of the soldered encoder
pins. If it hasn’t been trimmed already, trim it flush.

Turn the board face up so that KX1 is in the upper left corner.
Locate the pins for K1 in the upper right quadrant. Install C56(68) between pins 2 and 3 of K1 as shown in Figure 13. There are no
solder pads for C56. Cut the two relay pins and solder the capacitor
leads directly to the pads for the relay pins. Be sure the capacitor does
not exceed 5/16” (7.9 mm) in height above the board.

Install the following capacitors so that about 1/16” (1 mm) of leadshows between the capacitor and the board, so they can be folded
down against the board like you did with C39 earlier. DO NOT foldthese capacitors down against the board until you are instructed to
do so in later steps. If you fold them now, you will cover solder
pads you must reach to install other parts.
_

C15, .01 µF (103)_C3, .01 µF (103)_C14, 330 pF (331)_

C9, 01 µF (103)Install relay K1 (AGN2104H) to the left of R28 in the upper left
quadrant of the board as follows:_

Position the relay on the board. It will only fit one way.

_

Hold the relay in place and solder just one of its middle pins
to hold it in place.

_Re-heat the soldered pin while pressing down on the relay.
This will ensure that it is flush against the PC board.

_

Solder the remaining pins.

_

Trim all of the pins as short as possible.

Install relay K2 (AGN2104H) to the left of K1 following the sameprocedure.

Note: There are a number of components
shown in this picture that you have notinstalled yet.
Figure 13. Installing Capacitor C56.

ELECRAFT
Install electrolytic capacitor C53 (10 µF, 35 V) between diode D4
and capacitor C21 in the lower right corner of the board as follows:___

Insert the capacitor with the longer lead through the square
pad with the + symbol printed next to it. Check to ensure thestrip and minus ( - ) sign on the capacitor is on the side
opposite the + sign on the board.

With the board face up so that KX1 is in the upper left corner,
locate the printed outline for U4 on the right hand edge of the board
below U3. Install integrated circuit U4 (LM386) as follows:

Solder one lead and be sure the capacitor is firmly against theboard. Measure the height above the board and confirm that it
is less than 5/16” (7.9 mm) If necessary, reheat the lead whilepressing down on the capacitor.
Solder the remaining lead and trim both leads.

Install the following electrolytic capacitors using the sameprocedure:

i

35

_

C23 (100 µF, 10 V) about 3/4” (1.9 cm) above C53.

_

C20 (10 µF, 35 V) above C23.

_

C35 (100 µF, 10 V) next to C50 above the upper right cornerof the 3-digit display.

If you’re not wearing an anti-static wrist strap, be
especially careful to touch a ground frequently while installing
integrated circuits U4, U5 and U6 in the following steps.

_

Straighten the pins as necessary (see Figure 5).

_

Orient U4 so that the notch at the end is over the notch in theprinted outline on the board and pin 1 is in the round solder
pad (see Figure 11).

_

Bend the pins at opposite corners of U4 outward slightly tohold it in place.

_

Check to be sure that U4 is resting against the shoulders of all
8 pins on the top of the board.

_

Solder and trim all 8 pins.

i

Type NE612, NE602, SA612, and SA602 integrated
circuits are all functionally identical. Any of these may be supplied
for use at U5 and U6.
Install U5 (NE/SA612 or NE/SA602) near L10 and L8 at thelower center of the board. Use the same technique you used above.

i

In the following step, U6 must be fully seated before
soldering or it will interfere with the optional KXB30 30 m or
KXB3080 30 and 80m module. To ensure it is properly seated, adifferent installation method will be used.
Install U6 (NE/SA612 or NE/SA602) near encoder Z1 at thecenter of the board. Solder just one pin of U6.
Re-heat the soldered pin of U6 while pressing down on the it fromthe other side. You may hear or feel it settle into a lower position on
the board. Once you’re certain that it is mounted as close to the board
as possible, solder the remaining pins.

ELECRAFT

36

Install transistor Q9 (2N4124) to the right of U5. Be sure toorient the transistor according to the outline on the board (see Figure10) and insert the transistor so that the top is no higher than 5/16” (7.9mm) above the board.
Install transistor Q8 (2N4124) as shown in Figure 14. Bend theleads so that the transistor body fits within the printed outline with theflat side facing up. The round back of the transistor must lie against
the circuit board so that the transistor does not exceed 5/32” (3.9 mm)
in height above the board.

Install JFET transistors Q2 and Q3 using the same procedure
as Q8:_

Q2 (J309) to the right of Q8.

_

Q3 (J309) below Q2_

Measure each transistor to ensure it does not exceed 5/32”(3.9 mm) in height above the board.

On the bottom of the board, check the leads for JFET Q2 andintegrated circuit U6 to be sure they are soldered and cut flush.
Fold down against the board the capacitors you installed earlier asfollows. Measure each capacitor to ensure that it does not exceed 1/8”
(3 mm) in height above the board.

Figure 14. Installing Transistors Q2, Q3 & Q8. The Round Backof the Transistor Must Rest Against the Board.

_

C15 toward the “G” printed on the board.

_

C3 over the pins for integrated circuit U6.

_

C14 toward C3 and the pins for integrated circuit U6.

_

C9 over the pins for JFET Q2 (away from the large hole inthe board).

Turn the board face up with KX1 in the upper left corner andlocate the printed outline for trimmer CA just above transistor Q7 andthe upper right corner of encoder Z1.

ELECRAFT
Install trimmer CA as follows:_

Place a red trimmer in the CA position with the flat side of
the trimmer over the flat side on the printed outline.

_

Press the trimmer down against the board and spread the pins
to hold it in place. Note that the adjustment for the trimmer is
not visible from the top. It is accessed from the bottom
through the hole in the board.

_

Check to ensure the trimmer is sitting directly against theboard and then solder and trim both pins.

37

Open the package for four crystals: X2, X3, X4 and X5. The four
crystals are identical.

iWhile installing crystals in the following steps, be careful
not to flow too much solder onto the leads. Too much solder may
wick through the plated hole and cause a short to the case under
the crystal were it cannot be seen.
Install crystal X2 (4.9136) as follows:_

CB (red) directly below transistor Q7 on the right side of
encoder Z1.

Insert X2 (4.9136) into the board over the printed outline justbelow electrolytic capacitor C7. The crystal may go into theholes either way around .

_Note the location of the ground solder pad near the crystal.

CC (brown) to the right of trimmer CB.

_

Remove the crystal and solder to the case a discarded
component lead no more than 3/16” (4.5 mm) above thebottom of the crystal where it will go straight down throughthe ground solder pad. If desired, you may attach the groundlead after installing the crystal.

_Place the crystal on the board, threading the leads throughthe solder pad holes.

_

While holding the crystal vertical and firmly against theboard, wet your soldering iron with a drop of solder on the
tip and tack-solder one of the crystal leads.

_

Check to ensure the crystal is flat against the board andperpendicular to the board. If necessary, reheat the lead while
adjusting the position of the crystal.

_

Solder and trim the remaining crystal and ground leads.

Install trimmers CB and CC using the same procedure as CA:__

Bend ceramic capacitor C1 so that it touches the side of trimmer
CB. This will ensure that it does not interfere with the KXB30 or
KXB8030 option when it is installed.
Turn the board over so the bottom is facing up and jack J1 is in
the upper right corner.

ELECRAFT

38

Install remaining filter crystals using the same procedure you
used for X2.
_

X3 (4.9136)_

X4 (4.9136)_

X5 (4.9136)

i

Be certain the jack is mounted on the BOTTOM face ofthe circuit board as shown. It is very difficult to remove this jackwithout damaging the board if it is installed incorrectly.
Solder the center pin lead and recheck the alignment.

Turn the board so the bottom face is up with J1 in the upper rightcorner and locate the printed outline for antenna jack J2 in the upper
left corner.

Without disturbing the alignment of the jack, solder one of theheavy ground nubs to the board. Then re-check the alignment. Reheat
the nub, if necessary, to correct any misalignment.

ii

The next step requires an unusually large amount of heatfor soldering. Use a larger soldering tip if available.
Position jack J2 on the board so it is sitting within the printed
outline as shown in Figure 15.

The case will not close during final assembly if the jack is
not aligned as shown.
Solder the second nub on the jack and make a final alignment
check.

i

If you fitted your soldering iron with a larger tip to installJ2, replace it with a fine tip now.
Turn the board face up with KX1 in the upper left corner.
Fit headphone jack J4 in the printed outline in the lower rightcorner. The jack has six plastic nubs that hold it up off of the board
slightly. The pins will be flush with the solder pads on the bottom of
the board.

Figure 15. Installing J2.

Solder one pin and carefully recheck the position of the jack to
be sure all the plastic nubs are against the board. If necessary, reheat
the soldered pin while pressing down on the jack.
Solder the remaining pins. Be careful working around R15 and
R25 with your soldering iron.

ELECRAFTi

39

Turn the board top face up with KX1 in the upper left corner.

The optional KXAT1 ATU module plugs directly into
connectors J6, J7, and J8, which you’ll install in the following
steps. They MUST be positioned vertically (not tilted) or the ATU
module cannot be installed.

_

Turn the board bottom face up with jack J1 in the upper rightcorner.

Locate the printed outline for R2 next to electrolytic
capacitor C20 on the right side of the board. This is the
CENTER of the three outlines.

_

Position R2 (B10K) so the three signal pins and two large
mounting tabs are in the holes in the board.

_

Press down on the potentiometer until it rests solidly against
the board on the two metal nubs next to each mounting tab
and the shaft extends straight up at right angles to the board.

_

Solder one of the smaller pins, then recheck the alignment tomake sure the pot has not been moved.

_

Solder and trim the remaining small pins.

_

Solder the two large pins using just enough to make a goodelectrical and mechanical joint between the tab and the plated
hole. Do NOT try to fill the hole with solder.

Install two-pin jack J8 on the board just below antenna jack J2 in
the upper left corner as follows:_

Hold the jack vertical with your finger while tack-soldering
one pin.

_

Carefully inspect the jack to ensure it is vertical with respect
to the board and both ends of the jack are down against theboard.

_

Solder the pins, reheating the one you tack-soldered last toensure a good joint.

Install the following jacks using the same procedure.
_J7, three pins, just above J2 in the upper left corner.

_

J6, five pins, just below J1 in the upper right corner.

Separate the three potentiometers according to their values:_

Two 1k pots (B1K)_

One 10 k pot (B10K)

Install potentiometer R2 (B10K) as follows:

Install potentiometers R1 and R3 following the same procedure.
_

R1 (B1K) above R2.

_

R3 (B1K) below R2.

ELECRAFT40

i

In the following steps you’ll wind and install toroidal
inductors L1 and L2. They must be wound as exactly indicated in
the instructions or the transceiver will not operate correctly.3
Turn the board bottom face up with J1 in the upper right corner.
Locate the printed outlines for L2 and L1 in the upper left corner near
J2.
Locate the four toroid cores. There are two yellow T37-6 coresand two dark gray FT37-43 cores. Use the yellow cores to make L1and L2.

REMOVE INSULATION(SEE TEXT)i

Although the yellow and gray cores look similar, they havevery different electrical properties. You must use the yellow coresfor L1 and L2. The transceiver will not work if you use the wrong
cores. See Identifying Toroid Cores, page 9, for more information.
Wind L2 first as follows:3_

Cut a 13” (33 cm) length of red enameled wire.

_“Sew” the long end of the wire through the hole in the core
for a total of 14 turns as shown in Figure 16. Count one“turn” each time the wire passes through the center of thecore. There are no “half” or “quarter” turns when winding a
toroid. Match the winding direction shown in the figure or theleads won’t line up with the solder pads on the circuit board.

_

Spread the turns around the core so the finished result looks
like Figure 16.

Prewound toroids are available from an Elecraft-approved source. See
www.elecraft.com for details.

Figure 16. Toroidal Inductor L2.

i

In the next step the toroid leads will be stripped andtinned. The leads must be prepared correctly to provide goodelectrical contact when installed.

ELECRAFT
Strip the insulation and tin the leads of both inductors using oneof the following techniques:
1. Heat Stripping:a. Place a small amount of solder (a.k.a. a “blob” of solder)on your soldering iron.
b. Insert the clipped end of the wire into the hot solder. If theiron is hot enough, you should see the insulation bubble
and vaporize after 4 to 6 seconds.
c. Add more solder and feed more wire into the solder as theenamel melts. Continue tinning the wire up to the edge ofthe core, and then slowly pull the wire out of the solder.
d. If any enamel remains on the lead, scrape it away using
your thumbnail or sharp tool.
2. Burning: The insulation can be burned off by heating it with abutane lighter for a few seconds. Use sandpaper to remove theresidue, then tin the bare wires.
3. Scraping: Use a sharp tool to scrape the insulation away. Work
carefully and gently: do not nick the wire. Work around theentire circumference of the wire to remove all of the enamel
and tin the bare wires.
Place L2 over the printed outline on the board and thread its leads
through the solder pads.

41

Pull the leads tight so the toroid is sitting upright and against theboard. Check to see that some tinned lead is visible above the pad near
the toroid when the wire is pulled tight. If necessary, remove the toroid
and tin the lead closer to the core. It won’t matter of the tinned wire
touches the core itself. The toroid core is not a conductor.
Solder both leads.
Use your DMM to check for continuity across the solder pads. It
should be less than 1 ohm. If it is higher, you probably have a poorly
tinned toroid lead. Sometimes the leads look like they are soldered, but
because there is a film of enamel still on the lead, it is not making
contact with the solder pad. If the resistance is greater than 1 ohm,
remove the toroid, clean and re-tin the leads and reinstall it.
Wind and install L1 using the same procedure except that L1 has
13 turns. Use the second yellow toroid core for L1.

i

Do NOT attach L1 or L2 to the circuit board withadhesive, varnish, etc. The toroids will be adequately supported bytheir leads. Adhesives or other compounds may damage theenamel wire.
Bend a discarded 1/4-watt resistor lead into a “U” shape andinsert it into J7 pins 1 and 3 (J7 is the 3-pin connector adjacent toantenna jack J1; do not insert the wire into the 2-pin connector, J8).
This jumper completes the antenna circuit when the optional KXAT1
ATU is not installed.

ELECRAFT

42
Your kit includes an extra 22 k resistor (red-red-orange) for
use at R32. This resistor is not present on the Revision B or B1 PC
boards. It must be soldered in place in the location shown below,
on the bottom of the board between pins 2 and 3 of U4 (LM386N).
(It could also be soldered across the pins of C19, nearby, which
may be easier.) Trim and bend the leads approximately as shown.

Visual Inspection
Verify correct orientation (banded end) of diode D4, using theparts placement drawing (Appendix F).
Verify the correct orientation of each electrolytic capacitor. The
side of the capacitor with the strip and minus ( - ) sign must face awayfrom the + sign printed on the board.
Examine both sides of the PC board closely for solder bridges,
cold solder joints, or unsoldered components.

Resistance Checks
Make the resistance checks listed below with your DMM’s
negative (-) lead connected to circuit board ground at the hole next tocapacitor C6.
Test Point (+)

Make sure R32 is pressed flat against the bottom of theboard. Its leads must not be touching any adjacent pads, traces, orcomponents.

ResistanceU4 pins 2 & 3> 10k

U4 pin 4< 5 ohms

U4 pin 6> 1k

U4 all other pins

> 10k

U5 pin 3< 5 ohms

U5 pin 4, 5, 6 & 8> 1k

U5 all other pins

> 10k

U6 pin 3< 5 ohms

U6 pins 4, 5, 6 & 8>1k

U6 all other pins

> 10k

ELECRAFT

43

Alignment and Test - Part II
Temporarily mount the VFO knob on the shaft of encoder Z1.

i

Due to the small size of the KX1’s front panel, knobs are
not appropriate for use on the RF GAIN, FILTER and AF GAIN
controls. The shafts of these potentiometers, which are knurledand have molded index marks, are designed to function as knobs.
Unwrap the cover and set it near the circuit board so you can see
the legends identifying the controls and their functions.
Set AF GAIN fully counter-clockwise (minimum volume).
Make sure the POWER switch is turned OFF (S2).
Plug your power supply or battery into J1.
Turn on power to the KX1. The 3-digit LED display should show
the operating frequency. If not, disconnect the power source
immediately. Locate the source of trouble before proceeding.

Relay Test
Tap B AN D twice, quickly, to change bands. You should hear
relays K1 and K2 switching.
If necessary, use B AN D again to return to 7 MHz.

Sidetone Generator and Audio Amplifier
Plug in a pair of stereo headphones at J4 (at the right end of theboard), and rotate the AF GAIN control clockwise to about 12 o'clock.
Tap M E N U and use the VFO knob to locate the STL (sidetone
level) menu entry. Since you have no antenna connected, you mayhear some digital switching noise as you rotate the VFO knob or press
switches.
The sidetone level is set by editing the STL menu parameter.
Hold E D I T to show the parameter and turn on the sidetone. You canthen rotate the VFO knob to vary the sidetone level, from 0-3. Selecta comfortable level, then tap M E N U to turn off the sidetone and returnto the STL display.
Note: STL sets the sidetone volume level in relation to normal
received audio. The AF GAIN control sets the overall volume for both
received signals and sidetone.

ELECRAFT

44

Select the sidetone pitch menu entry (STP) using the VFO knob.
Hold E D I T to turn on the sidetone and edit the pitch parameter. The
pitch can be varied from 500 to 650 Hz using the VFO knob. Selectthe desired pitch, then tap M E N U to end parameter edit and return to
STP.
Tap M E N U again to return to the normal display.

S-Meter and Voltmeter Displays
The DISP function (holding B AN D + R I T together) selects oneof three display modes. On power-up, frequency display mode will bein effect. Hold B AN D + R I T to select S-meter mode, which will flash
a 6-segment bar graph across the upper portion of the display. The
display may then go blank or show 1 or more segments, since the Smeter has not been calibrated. (The SIG menu entry is used for thispurpose; it is described later.)Hold B AN D + R I T together again to select voltmeter mode. You
should see BAT (battery) flash briefly on the LED. Your approximate
power supply or battery voltage will then be displayed and will flash
slowly.
Return to frequency display mode by holding B AN D + R I T
again. nor (normal) will flash briefly before the frequency isdisplayed.

Keyer
Plug a keyer paddle into the key jack (J3). The paddle must have astereo (2 circuit) plug. If you don't have a keyer paddle, you can still
test the DOT and DASH lines by unscrewing the shell from the
supplied stereo plug and inserting it in the KEY/PADDLE jack. Use aclip lead or a screwdriver to short the tip or ring terminals to theground terminal to trigger dots or dashes.
Tap M E N U and rotate the VFO knob to locate the INP menu
entry (CW input device selection). Hold E D I T to see the parameter.
Turning the VFO knob selects HND (hand key or external keyer),
PDN (paddle normal) or PDR (paddle reverse). Tap M E N U twice
to return to the VFO display.
The keyer speed may be varied from 8 to 50 WPM. Display the
keyer speed by holding S P E E D , then adjust it using the VFO knob.
Tap any switch to return to the frequency display. (The KX1 does nottransmit when adjusting the keyer speed.)
While listening with headphones, test the keyer paddle to verify
that both dot and dash are working.

ELECRAFT

45

Receiver Alignment

Set the RF GAIN control fully clockwise.

There are two receive band-pass filters to align. The trimmer
capacitors are adjusted through the bottom of the board as shown in
Figure 17. The 14 MHz (20 meter) filter has two adjustments, labeled
20A and 20B on the PC board, while the 7 MHz (40 meter) filter has
just one, labeled 40.4
Two additional holes, labeled 30A and 30B, are provided for use withthe optional 30-meter or 30/80 meter modules (KXB30 or KXB8030).
The 14 MHz (20 m) trimmers must be aligned first, then the 7 MHz(40 m) trimmer, as explained in the following steps.
20A

K2

20B

Set the FILTER control fully clockwise.
Plug in a pair of headphones or an external speaker, and adjust
the AF GAIN control until you hear some background noise. If you do
not hear any noise, refer to Troubleshooting.
If the present band is not 14 MHz (20 m), tap B AN D twice
quickly to select it.
Set the VFO to about 14100 kHz. Tap B AN D if necessary toverify that you're in the right 100-kHz segment.
Connect an appropriate antenna for the 20-meter band. At
minimum, connect approximately 15-30 feet (5 to 9 meters) of any
type of wire to the center conductor BNC connector J2. In general, thelonger and higher the antenna, the more signal strength that will beavailable during receiver alignment.

K1

40

i

30B

30A

BOTTOM OF BOARD

Figure 17. Trimmer Adjustments.

4

Only one adjustment is required on 40 meters because the first tuned circuit
is somewhat broadly resonant on this band, allowing the use of a fixedcapacitor.

Receiver alignment will be easiest if you use a controlled
signal, i.e. from a ham-band transmitter, signal generator or noise
generator. In all cases, use a signal that is weak enough to not activate
the KX1’s AGC; otherwise, it will be much more difficult to find thecorrect settings for the trimmer capacitors. If you use a transmitter, besure to connect it to a dummy load and operate it at low power.

ELECRAFT

46

Locate a small flat-blade screwdriver or tuning tool for use inadjusting the trimmer capacitors. Test the tip of the tool to make sure it
will through the access holes and can turn the trimmers. If the handle
is not insulated, wrap the end with tape to prevent your handcapacitance from affecting the adjustment.

i

The trimmer access holes on the revision B and B1 KX1PC boards are plated through and grounded. This may makealignment more difficult if you’re using a tool with a long metal
shaft, rather than a tuning tool with just a metal tip. This is not asafety hazard, but you may need to remove the tool after eachadjustment to check the signal amplitude. (The PC board revision
letter can be found in the upper left-hand corner of the PC board,on the top side.)
Tap B AN D twice, quickly, to select the 14-MHz band.
While listening to atmospheric noise or a weak CW signal, peaktrimmer capacitors 20A and 20B. If the peak is not clear, reduce thesignal input level (the AGC may be getting activated). Do not turnthe RF GAIN control counter-clockwise, as this will broaden thetuning peaks, making them more difficult to identify.

i

If you don’t hear band noise or signals, be sure you
installed the jumper across the outer pins of J7 as described on
page 41.

Switch to an appropriate antenna for this band, if available, or use
the wire antenna recommended earlier.
While listening to noise or a weak signal, peak trimmer 40.

AGC and S-Meter Test
Turn the KX1 on and connect an antenna or signal generator.
S-meter display mode provides a bar graph to indicate
approximate received signal strength. To select this mode, hold
B AN D + R I T . You’ll see a brief bar-graph test pattern, then thedisplay may go blank or show one or more bars.
Tune in a strong signal. (Whenever you move the VFO, the Smeter bargraph will replaced with the frequency display.) Once thesignal is tuned in, the AGC should be activated, as indicated by anincrease in S-meter reading.5 The S-meter zero point and scale can be
adjusted, if necessary, using the SIG menu entry (page 65).

i

Since the KX1 uses audio-derived AGC, the initial code
element from a very strong station may be heard at a louder
volume. This is due to the time it takes for the AGC detector
capacitor, C53, to charge. This effect is lessened somewhat by thelimiting action of U4 (AF amp), since U4 is operated from a low
voltage. (See schematic, Appendix B.)

Tap B AN D twice (quickly) to select the 7 MHz band. Set the
VFO to about 7100 kHz.

5

Each bar corresponds to roughly two S-units, so that 4 or 5 bars indicates
about an "S-9" signal.

ELECRAFT

47

Receive Current Drain Test (Optional)

Operating Frequency Calibration (Optional)

The current drain in receive mode is about 35 mA (with the LED
menu entry set to 0, 1, or 2). If the current drain is significantly
lower or higher than this, it could indicate a problem.

The operating frequency display may be off by as much as ± 200Hz
until calibrated, due to variations in the 50-MHz reference oscillator
and BFO components. Accuracy can be improved to approximately ±10 or 20 Hz using the BFO and DDS menu entries.

To check the current drain, set your DMM for DC milliamps andtemporarily insert the DMM in series between the KX1 and the power
supply. Turn the KX1 on and note the current: _____ mA.

While it is possible to do operating frequency calibration at this time,
we recommend that it be done after assembly and test have been
completed. The calibration procedure is described on page 68.

ELECRAFT

48

Assembly - Part III
In Part III you’ll install and test the transmitter and lowpass filter
components.
Remove the VFO knob if you haven’t done so already.
Turn the board top face up with KX1 in the upper left corner.
Install the following 1/4 watt resistors to the upper left of encoder Z1:_

R9, 300 ohms (org-blk-brn).

_

R11, 10 ohms (brn-blk-blk)_

R31, 1k (brn-blk-red) Note: On some boards, R31 may be
printed in reverse (mirror image).

Turn the board bottom face up with jack J1 in the upper rightcorner. Install the following 1/4 watt resistors near the center of the
top edge.
_

R30, 22 ohms (red-red-blk) above relay K1.

_

R26, 22 ohms (red-red-blk) above electrolytic capacitor C7.

_

R27, 22 ohms (red-red-blk) above R26.

_

R10, 47 ohms (yel-vio-blk) to the right of R27.

_

R24, 22k (red-red-org) on the top edge of the board
above R10.

Install zener diode D7 (1N4756A) next to resistor R30. Be sure toalign the banded end of the diode over the band on the board.
Install trimmer potentiometer R4, 100 ohms (101), next todiode D7 and resistor R30 as follows:_

Position R4, 100 ohms (101), and hold it in place while tacksoldering one pin.

_

Check to be sure all the shoulders of all three pins are against
the board, the solder and trim all three pins.

_

Set R4 fully counter-clockwise.

ELECRAFT
Turn the board top face up with KX1 in the upper left corner.
Install the following capacitors in the area above encoder Z1. Be sure
to check the each capacitor to ensure it is no more than 5/16” (7.9 mm)above the board.
_

C42, .01 µF (103) to the left of electrolytic capacitor C35 on
the top edge of the board.

_

C34, .01 µF (103) to the right of electrolytic capacitor C35 on
the top edge of the board.

_

C41, .01 µF (103) near the upper left corner of encoder Z1.

_

C43, .1 µF (104) above C41.

_

C44, .022 µF (223) near RF Gain potentiometer R1.

49

i

In the following steps you’ll wind and install toroidal
inductors L3 and transformer T1. They must be wound as exactly
indicated in the instructions, or the transceiver will not operatecorrectly.6
Turn the board bottom face up with J1 in the upper right corner.
Locate the printed outlines for L3 and T1 near the top center of theboard to the right of trimmer pot R4.
Locate the two dark gray FT37-43 cores.

i

Wear your ESD wrist strap or touch a ground frequently
while installing the transistors in the following steps.
Install the following transistors. Be sure the top of the transistors
is not more than 5/16” (7.9 mm) above the board.
_

Q1 (J309), directly to the right of the three-digit LED display.

_

Q5 (2N3904) near the upper left corner of encoder Z1.

_

Q4 (2N4124) above Q5 near the upper edge of the board.

THIS LEAD PASSESOVER FRONT OF
CORE

REMOVE INSULATIONUP TO THE CORE ON
BOTH LEADSLEAVE THIS SPACE ON CORE OPEN

Figure 18. Winding Inductor L3.

6

Prewound toroids are available from an Elecraft-approved source. See
www.elecraft.com for details.

ELECRAFT

50

Wind toroidal inductor L3 on one of the FT37-43 cores
as follows:_

Cut a 14” (36 cm) length of red enameled wire.

_“Sew” the long end of the wire through the hole in the core
for a total of 18 turns. Match the winding direction shown in
Figure 18. Count one “turn” each time the wire passes
through the center of the core. There are no “half” or“quarter” turns when winding a toroid.

_
_

4

3

Spread the turns around the core so the finished result looks
like Figure 18.

_

Cut an 8” (20 cm) length of red enameled wire.

_“Sew” the long end of the wire through the hole in the core
for a total of 8 turns. Match the winding direction shown in
Figure 15. Count one “turn” each time the wire passes
through the center of the core. There are no “half” or“quarter” turns when winding a toroid.

_

Spread the turns around the core so the finished result looks
like Figure 16.

_

2

TIN ALL FOUR LEADS UP TO THE CORE.

Strip the insulation and tin the leads like you did earlier for
L1 and L2 (See page 41).

Wind toroidal transformer T1 on the remaining FT37-43 core
as follows:

1

Figure 19. Winding Transformer T1.
Install toroidal transformer T1 first as follows. It will be easier tothread all four leads through the proper holes in the board if you install
it before L3.
_

Thread the leads through the holes in the board. Double
check to ensure you have the right leads in the right holes(see Figure 19). The inductor stands up vertically over the
printed outline. You will notice that lead 4 cannot be pulled
tight without dislodging the turns. This is normal. Leave
enough slack in that lead to avoid disturbing the position of
the winding.

Cut a 6” (15 cm) length of green enameled wire.

_

Solder all four leads.

_

Wind two turns in between the other winding exactly as
shown in Figure 19.

__

Strip the insulation and tin all four leads like you did for theother inductors.

Use your DMM to check for continuity between pins 1 and 2,
then between 3 and 4. The resistance must be less than 1 ohm
in both cases. If it is higher, you probably have a poorly
tinned toroid lead. It must be fixed before continuing.

ELECRAFT

51

Install toroidal inductor L3 and solder both leads. Check forcontinuity (less than 1 ohm) between the solder pads.

Place the front panel (top cover) face down on a soft cloth to
avoid scratching it.

Do NOT attach L3 or T1 to the circuit board with adhesiveor other compounds. They should be supported only by theirleads.

Remove the paint from around the screw holes where the shortstandoffs will contact the front panel as shown in Figure 21. Use
sandpaper or a sharp knife. Clean the panel thoroughly to remove allof the residue when you are done.

Install two pairs of standoffs in the holes at the edges of the board
as shown in Figure 20. The front panel / top cover will attach to theshort standoff. One pair of standoffs installs near J8 and K2 (on thebottom face of the board) and the other pair installs in the hole near P1
and J6.

Inspect the area where the thermal pad will mount and be certain
there are no burrs that could poke through the thermal pad. Burrs aremost likely to be found around the hole. Sand file any rough edgessmooth.

i

TOP FACE OF
BOARD

5/16” STANDOFFNO WASHER HERE!

SPLIT WASHER

3/4” STANDOFF

Figure 20. Installing Standoffs on Circuit Board.

Figure 21. Preparing Top Cover for Installation.

ELECRAFT

52

Locate the thermal pad. Leave it on the backing paper while you
remove the piece filling the hole near one end. Then remove thebacking and place the pad on the inside of the cover over the area you
sanded with the hole in the pad aligned with the hole in the cover (seeFigure 22).

Position the red filter over the LED display opening. Use theclear tape to secure it on the top and bottom edges as shown in Figure
23. Even though the tape is transparent, keep it outside of the window
area so the edge of the tape is not visible from the front of the unit. Be
careful not to cover the pushbutton switch holes with the tape.

Figure 23. Installing Display Filter.
Figure 22. Installing Thermal Pad.

ELECRAFT

53

Check your kit to determine whether a 2SC2166 (metal tab) or a
2SC5739 (black plastic tab) transistor was supplied. Both transistors
provide equal performance, but their installation is different because
the metal tab on the 2SC2166 must be insulated from the mounting
hardware. Install the transistor exactly as described in the following
steps.
Bend Q6’s leads into a gentle 90-degree curve (see Figure 24).
Note that the flat side of the transistor faces away from the circuitboard. Wrapping the leads around a round screwdriver shaft or drill
bit helps avoid sharp kinks in the bend.

Locate the silk-screened outline for Q6 at the top edge of thecircuit board. Install the 3/16” (4.76 mm) standoff on the circuit board
using a 3/16” pan head screw and two split washers as shown in the
figure. The split washer under the standoff is important to reachthe proper height so Q6 will come in contact with the cover. Be
sure the screw head or washer is not touching the windings on L3 on
the bottom of the board. They may touch the toroid core in the space
between the windings.
Place Q6’s leads in the holes in the circuit board. Do not solder
them until instructed to do so.

Figure 24. Installing Power Amplifier Q6.

ELECRAFT

54
Temporarily secure Q6 to the standoff with a 4-40 flat headscrew. Tighten the screw enough to hold Q6 securely and parallel tothe circuit board.
Use your long-nose pliers to adjust the leads so the flat side of thetransistor is parallel to the circuit board. The flat side must face
AWAY from the board. It will rest against the thermal pad you
installed in the top cover and must make good contact to transfer heatefficiently.
Solder the three leads to Q6. Trim them flush on the bottom sideof the board.
Remove the flat head screw holding Q6. If a 2SC2166 is
installed, the soldered leads should hold the shoulder washer in place.
Conduct a thorough visual inspection of the board. Use amagnifier. Check especially for the following:i_

Diode D4 is oriented correctly as shown in the Parts
Placement diagram in Appendix F.

_

All joints soldered with no shorts between solder pads.

_

All components installed. On the bottom are some labeled
pads that will have no wires in them. They are connection
points for the optional KXB30 30 meter or KXB3080 80
meter band module. These pads are labeled “A”, “B”, “C”,
“D”, “5” and three pads labeled “G”.

If you installed a 2SC2166 (metal tab) transistor at Q6,
NEVER install a metal screw in the tab of Q6 when the unit is outof its case for testing. The metal tab of Q6 is connected to the +side of the power supply and the screw will short the supply toground when power is applied. This may cause serious damage tothe circuit board or other components.

Connect your DMM ground lead to one of the metal stand-offs
mounted on the board and make the following resistance checks:_

Q4 Emitter (terminal farthest from edge of board) 20
to 24 ohms_

Q4 Base (center terminal) > 10k_

Q4 Collector (nearest edge of board) > 10k_

Q5 Emitter (terminal farthest from edge of board) 50
to 70 ohms_

Q5 Base (center terminal) > 10k_

Q6 collector (metal tab if 2SC2166): > 500 ohms

Place the three button caps on the pushbutton switches. Press
down on each cap to snap it in place.
Fit the board into the top cover as follows:_ The control shafts will fit through the holes.
_ If the pushbutton switches don’t line up properly with theholes in the cover, use a long tool to reach between the coverand the circuit board to nudge the caps into the holes.
_ Finally, you will need to push down gently on the key jack tomake it snap into its hole in the cover.
_ Check the standoffs at both ends and confirm that they are
resting against the cover.
Secure the board to the cover with three 4-40 x 1/4” flat-headscrews. Do not over-tighten any of these screws.

ELECRAFT

55

Turn the unit face down on a soft surface and measure theresistance between either solder pad for toroid L3 and ground. It
should be > 500 ohms. If it is less, you must find the cause before
proceeding. If the metal tab 2SC2166 is installed at Q6, the most likely
cause will be that the shoulder washer has slipped out or the metal tabon the transistor is touching the case instead of the thermal pad.
Install the knob on the encoder shaft.

Find the battery holders and inspect the bottom of one. Note theridges and nubs that provide a space for wires under the holder. The
holder has one wire running between two molded ridges that connect
the opposite corner cells together.
In the following steps you will install and wire the battery
holders. First, study the wiring drawing in Figure 25. The two holders
are wired in series. The wires must run against the bottom cover andunder the holders as shown to avoid interfering with other components
when the KX1 case is closed.

ROUTE BLACK WIRESUNDER BATTERY HOLDER
AND AROUND SCREW.
BE SURE WIRES LIE FLAT AND
DO NOT CROSS OVER EACH OTHER.
RED
2-3/4” (7 CM)REMOVE PAINT
FROM AROUND
HOLE ON INSIDE
OF COVERBLACK
CUT TO MATCH
LENGTH OF RED

REMOVE PAINT
FROM AROUND
HOLE ON INSIDE
OF COVER
ROUTE REDWIRE UNDERBATTERYHOLDER AND
AROUND
CORNER
NUB

BLACK
4” (10.2 CM)

SPLICE MUST LIE FLAT ON BOTTOM.
KEY JACK J3 AND CRYSTALS ON THE
BOTTOM OF THE CIRCUIT BOARD FIT IN
THIS AREA.

RED
3-1/4” (8.3 CM)

TUCK EXCESS RED WIRE
UNDER BATTERY HOLDER.

Figure 25. Wiring the Battery Holders.

ELECRAFT

56

Begin by removing the paint from around the holes on the insideof the bottom cover where it will attach to the stand-offs on the circuitboard. There are two holes; one at each end of the cover (see Figure
25).
Select one battery holder and cut the red wire to 3-1/4” (8.3 cm)
in length. Strip 1/4” (6 mm) of insulation off of the end. These are
stranded wires. Be careful not to knick or break the strands. Leave theblack wire its full, original length.

Slip the three wires shown in Figure 25 under the edge of theholder as follows:_

Position the red wire so it goes under the holder and aroundthe nub at the corner.

_

Position the two black wires so the screw will prevent their
being pulled out from under the holder. Be sure the wires lie
flat and do not cross over each other under the holder.

Insert the remaining screw in the holder and tighten both screws.

iRepeated insertion and removal of the 2-56 screws used in
the following steps may result in stripping the threads in thebottom cover. To avoid this, study the illustration and instructions
carefully before inserting the screws. In the event that the 2-56
screw threads do become stripped, you’ll need to replace thesupplied screws with longer screws, along with 2-56 hex nuts.

Wiggle all three wires running under the left battery holder to be
sure they are not being pinched. You should be able to move the free
end of the black wire and see it move where it emerges from under theholder without interfering with the other wires. If necessary, loosen or
remove the top screw and adjust the wires so each one lies flat under
the holder. Tighten both screws when you are done.

Mount this holder in the right hand position as shown in Figure
25 using two 2-56 screws. Do NOT over-tighten the screws, as thismay strip the threads. Be sure the wires exit at the left end as shown.

Cut a 1” (2.5 cm) length of the black shrink-tubing supplied andplace it over the end of the red wire on the right hand battery holder.

On the second holder, cut the wires as follows:_

Red: cut to 2-3/4” (7 cm) in length and strip the insulation off
of 1/4” (6 mm) at the end.

_

Black: cut to 4” (10.2 cm) in length and strip the insulation
off of 1/4” (6 mm) at the end.

Position the second holder on the bottom cover oriented as shownand start a screw in the hole nearest the edge of the cover (closest to
the bottom in Figure 25). Do not tighten this screw yet. Leave it loose
enough so that the other side of the holder can be lifted up off of thecover far enough to slip wires underneath.

Twist the ends of the red wire from the right holder and the black
wire from the left holder together to join them. Make the joint smalland smooth. Solder it.

ELECRAFT
Slide the shrink tubing you placed on the red wire over the joint
and shrink it in place to insulate the connection. You can shrink itusing hot air from a blow dryer or by simply placing your soldering
iron very close to the tubing and allowing its radiant heat to shrink it.
If you place the barrel of a hot soldering iron (the part just behind thetip) where it almost touches the tubing and parallel to it, the tubing
should begin to shrink in about 30 seconds. Repeat at two or threeplaces around the tubing to shrink it evenly and snugly.

57

Insert the terminals into the housing until they latch. Tug on thewires to verify that the terminals are locked in place.
Double check your installation by attaching J5 to plug P1 andverify that the red wire goes to the terminal marked + on the circuitboard. If you got them backward, press gently with a thin screwdriveror knife blade in the slots on the housing to release the terminals.
RED WIRE

Slide the excess red wire under the right hand holder as shown so
the splice and wire lies down near the bottom cover. When the unit isassembled, the space between the battery holders is taken up by the
Key jack (J3) and the crystals on the circuit board.
Line up the black wire with the red wire in the upper left cornerthat will go to the power plug. Cut the black wire to the same length as
the red wire and strip 1/4” from the end.

RED WIRE MUST GO
IN THIS SIDE

HOUSING
BLACK WIRE

Figure 26. Assembling Battery Supply Jack J5.

Locate the crimp terminals and housing for plug J5 (Figure 26).
Crimp and solder the terminals to the stripped red and black wires.

i

We strongly recommend the use of 1.5-volt cells,
preferably 2.9 AH lithium (Energizer type L91) or alkaline.
1.2-volt cells, e.g. NiMH, can also be used, but have somedrawbacks. See page 62 for details.

This completes Part III of the Assembly.

ELECRAFT

58

Alignment and Test - Part III
Make sure the KX1 is turned off.
Connect a 12 to 14-V, 1-amp power supply (or battery) to J1.
Make sure trimmer R4 is fully counter-clockwise (drive level).
Connect an antenna that is adequate for receiver testing.
Plug in a pair of stereo headphones or a speaker at J2.
Turn on the KX1. If the display doesn’t appear, turn the KX1 offand disconnect the power supply. Check resistance from the tab of Q6
to ground and from pin 1 of the MCU (U1) to ground. Both should beover 500 ohms. If the tab of Q6 measures low resistance, look for D7
installed backward or a solder bridge across the pins of Q6. If pin 1 of
the MCU measures low, put on a wrist strap (or touch ground) andremove U1, then re-check the resistance. If it’s still low, you could
have a short on the 5-volt or 2.7-volt lines.
Switch to voltmeter display mode (using B AN D + R I T , twice) tomake sure that the battery or power supply voltage is not being pulled
down when the KX1 is turned on. If it is, it could indicate a short orincorrect component somewhere in the transmit stages.

Repeat the receiver alignment steps (page 45). This is necessary
because some components added in Assembly Part III may affect thetuning of the receiver’s band-pass filters.

i

If receiver gain seems to be too low after re-alignment, you
may have an assembly error in the transmit stages, low-pass filter, or
T-R limiter (Q7). Turn the KX1 off, remove the top cover, and recheck the orientation of all diodes, transistors, and ICs. Look for shorts
on both the top and bottom of the board in the transmitter area. (Alsosee Troubleshooting.)
Turn the KX1 off.
Connect a 50-ohm dummy load to the antenna jack, along with awattmeter if available. The dummy load should be rated at 5 watts or
higher.
Connect a key or keyer paddle.
Set R4 fully clockwise.
Turn the KX1 on.

ELECRAFTi

TUNE mode (key-down) is activated by pressing the M E N U
and B AN D switches together. Tapping any switch or the keyer paddle
will cancel TUNE. During TUNE, the display will show tun. (If the
KXAT1 ATU option is installed, the display will instead show both
power output in watts and SWR. Refer to the KXAT1 manual for
details.)

59

40-Meter Transmit Test
Switch to 40 meters (7 MHz). Set the VFO to about 7100 kHz.
Put the KX1 into TUNE mode by holding M E N U + B AN D . You
should see tun on the display. Listen for the KX1’s signal in themonitor receiver and/or check the wattmeter indication, then exit
TUNE mode by tapping any switch.

20-Meter Transmit Testi

Switch to the 14-MHz band using B AN D . Set the VFO toapproximately 14100 kHz.

If 40-meter power output is less than 3 to 4 watts with a 12-14
V supply, see Troubleshooting.

If a monitor receiver (or transceiver) is available, connect a very
short antenna wire (1 to 3 feet) to its RF input and set it to the KX1’s
indicated VFO frequency.

If both bands have adequate output power but 20 meters ishigher, you should adjust the windings of toroidal inductor L2. To dothis, “squeeze” the turns of L2 together slightly so that they occupy
only about 70% of the core’s circumference. With L2 at its optimal
turns spacing (for best harmonic rejection), 20 meter output will be
about 0.3 to 0.6 watts lower than 40 meters.

i

Do not remain in TUNE mode for more than 5 to 10
seconds at a time. If you cannot hear the KX1 in the monitor
receiver, or if you suspect there’s a problem, cancel TUNE mode
immediately and see Troubleshooting.

Keying Test
Connect a keyer paddle or hand key to the KEY/PADDLE jack.

Put the KX1 into TUNE mode by holding M E N U + B AN D . You
should see tun on the display. Listen for the KX1’s signal in themonitor receiver and/or check the wattmeter indication, then exit
TUNE mode by tapping any switch.

i

The wattmeter should indicate approximately 3 to 4 watts
with a 12-14 V supply. If power is significantly lower than this, theKX1 could be drawing more current than your power supply or battery
can handle, or R4 may not be set fully clockwise. If neither of these
seems to be the problem, see Troubleshooting.

Key the KX1 while listening in the monitor receiver. The keying
should sound clean and stable. During keying, one bar will be shownon the LED bargraph. (If the KXAT1 ATU is installed, the bargraphwill instead show approximate power output in 0.5-watt increments (0to 3 watts).
Turn the KX1 off and disconnect the power supply, key or
paddle, and antenna.

ELECRAFT

60

Final Assembly
Be sure that you removed the paint from around the bottom coverholes (see Figure 25).
Three self-adhesive feet are supplied for the bottom cover. Threefeet provide excellent stability on uneven surfaces. Position the feet on
the bottom as shown in Figure 27.

Place the serial number label inside the top cover as shown in
Figure 28. Note: The label is placed on the inside to protect it during
field operation. You can easily check the serial number whennecessary by removing two thumb screws and pulling open the bottom
cover.

Figure 28. Installing Serial Number Label.
Figure 27. Installing Feet.

ELECRAFT
Components on the bottom of the board must have an overall
height of no more than about 1/8” (3 mm) above the PC board in thearea shown below (See Figure 29 ). Fold down or re-solder
components if necessary. Also trim any long component leads whichwere not trimmed earlier.

61

iWhen you install the bottom cover in the next step, be sure
not to pinch the battery cable under the nearby long standoff.
Fit the bottom cover in place and secure it with the two 4-40
black knurled thumbscrews.
This completes assembly of your KX1 Transceiver. You should havea number of washers, screws, and other hardware left over. These
items have been provided as spares. Please read the Operation section,
which follows, and try each of the KX1's features. If you're new to
QRP, be sure to read the QRP Operating Tips section (page 70).

iFigure 29. Checking Component Clearance.

Set the chassis (top cover and circuit boards) next to the bottom
cover as shown in Figure 29 and attach battery connector J5 to plug P1
on the main circuit board.

If you have purchased KX1 internal options, do not installthem until becoming familiar with basic KX1 operation. Options
can be installed in any order. (All KX1 options are described on
page 71.)ELECRAFT

62

Operation
This section covers all KX1 connectors, controls, and operating
features. For a one-page Quick Reference, see Appendix G.

External Power Supply

Internal Battery

You can connect any 7-14 V DC power supply or battery to J1,
although you should use the minimum recommended voltage (8 V)
when possible. The KX1 will run from whichever is higher in voltage,the internal battery or the external supply. Transmit current drain willbe 300-700 mA, depending on the supply voltage.

Connect the internal battery to P1 on the PC board. Make sure thebattery wires aren’t pinched when you install the bottom cover.

Headphones or External Speaker

Connections

Battery Selection: For best performance, use 1.5-volt cells (9 volts—
see table). Energizer lithium type L91 or fresh Alkaline cells arerecommended. Lithium cells are more expensive, but have high energy
density, a flat discharge curve, and weigh less than Alkalines. 1.2-voltcells (e.g. NiMH) can also be used, but will provide lower output andreduced operating time, and near end of charge will not meet the
KX1’s minimum supply voltage spec (7 V). You must remove
rechargeable batteries (e.g., NiMH) for charging.
BatteryType
Lithium
Alkaline
NiMH

Voltage(6 cells)
9V
9V
7.2 V

Amphours
2.8-2.9
2.2-2.7
1.6-2.3

Output(watts)1.5-2.0
1.5-2.0
0.75-1.0

Weight(6 cells)
3 oz.
5 oz.
5 oz.

Low-Battery Warning: If the supply voltage drops below the value
set in the BAT menu entry, you’ll see BAT LO on the LED every
five minutes. Set BAT to 7.5 V for Alkaline or Lithium cells, 6.5 V
for NiMH, and 10.5 V for an external 12 V battery.

The AF output jack, J4, can accommodate either headphones or asmall speaker (8-32 Ω). A stereo plug is required. Earbud-style
headphones are recommended (Sony MDR series or equivalent, withsensitivity of 108 dB/mW). They are lightweight, sensitive, and mask
wind noise well.

Antenna
Any resonant antenna can be connected to J7. With the KXAT1 ATU,
you can connect random-length wires, often without any feedline (seeKXAT1 manual). With a KXAT1 installed, power and SWR will be
displayed in TUNE mode, and power output is shown on the bargraphduring keying. If no KXAT1 is installed, the display will show one bar
on transmit, and tun in TUNE mode.

Keying Device
You can connect a hand key or external keyer to J3, or connect a
paddle (such as the optional KXPD1) and use the KX1's built-in
memory keyer. A stereo plug is required. You can also use the KX1's
front-panel buttons to send CW (see page 68).

ELECRAFT

Controls and Display
Power Switch
Set POWER ON to turn on the KX1. If the LED display is too dim,hold M E N U , B AN D , or R I T at power-up. This selects maximum
LED brightness and also turns on audible CW switch feedback at 10,
20, or 30 WPM respectively (see page 69).

Lamp Switch
Set LAMP ON to turn on the lamp at the front-left edge of the KX1.
The lamp can be used to illuminate a log book placed in front of the
KX1, or as a flashlight. In an emergency it can be used for visible
signaling. The white LED used is extremely efficient. Its current
requirement varies with supply voltage, from about 5 mA at 7 V to 15
mA at 14 V. You can substitute a red LED if desired.

LED Display
The 3-digit LED display shows the operating frequency, S-meter or
power output bargraph, menu entries, etc. Brightness and ‘on-time’ areprogrammable (see LED, page 65). You can also use audible CW
switch feedback in addition to the display (page 67).
Brightness: The display is most useful in low to moderate lighting
situations, where it requires only about 1-3 mA total current. Brighter
settings are also available that require up to 10 mA. If the display is
too dim when the KX1 is first turned on, you can quickly selectmaximum brightness, and simultaneously enable CW feedback on
switch press, by holding one of the three pushbutton switches when
the KX1 is turned on (see Power Switch, above).
Decimal Points: The decimal point shifts to indicate the VFO tuning
rate, and is flashed when RIT is enabled.
Bargraph: In S-meter mode, the bargraph indicates received signal
strength (see SIG, page 65). On transmit, it shows 1 bar per 0.5 W
output if the ATU is installed, and 1 bar otherwise.

63

VFO Knob/Tuning Rate Switch
This control adjusts the VFO frequency, RIT offset (R I T , next page),keyer speed (W P M , next page), and is also used in the menu (page66). Tapping the knob selects 100-Hz or 10-Hz VFO steps. Holding it
for 0.5 seconds selects 1 kHz or 5 kHz VFO steps, depending on thereceive mode (page 66). It is also used in along with other switches toactivate certain advanced features.
Transmit frequency ranges: The KX1 transmits only in the hambands (7.0-7.3, 10.10-10.15, and 14.0-14.35 MHz). Transmit will be
prevented once you move a few kHz outside of each band, and you'll
see END flashed on the display.

Potentiometers
RF GAIN: Sets the receive RF gain. Normally set fully clockwise, but
can be rotated counter-clockwise to attenuate strong signals.
FILTER: Adjusts the receive crystal filter bandwidth over a range ofabout 300 to 2000 Hz. Narrow-bandwidth settings can be used toreduce interference from nearby signals when copying CW. Widerbandwidth settings are useful for copying SSB and AM.
AF GAIN: Sets the receive audio output level. The sidetone volume
can be set higher or lower in relation to receiver audio using the STL
menu entry (page 65).
POWER LEVEL (R4 - internal): This trimmer potentiometer isaccessible through a hole in the bottom cover, and can be set using asmall tuning tool or flat-blade screwdriver.

i

For best performance, keep R4 set fully clockwise, unless
you must reduce power to conserve battery life. This control
should not be adjusted frequently; trimmer potentiometers have afinite life (100-200 rotations).

ELECRAFT

64

Pushbutton Switch Functions

Switch Combinations

There are three small pushbutton switches below the display. A fourth
pushbutton switch is built into the VFO knob.

M E N U + B AN Da switch to access its upper function (white label); H O L D aswitch for 1/2 second to access its lower function (yellow label). Someswitches can be held in combination as described at right.
T AP

Note: The M E N U , B AN D , and R I T switches can also be used at
power-on to select maximum LED display brightness and turn on CW
feedback on switch press at 10, 20, or 30 WPM (see page 67).
Switch T AP and H O L D Functions
MENU

Displays the menu (see next page)

EDIT

Edits current menu parameter

B AN DOne tap shows frequency (MHz first, then kHz;Lor U is added in LSB or USB modes). Two quick taps
selects the next higher band.

WPM

Allows keyer speed adjustment using VFO control (850 WPM) without transmitting.

TUNE: Initiates TUNE mode (key-down)

Note: Limit TUNE time to 10 seconds on, 10 seconds off.
If a
KXAT1 ATU is installed, you’ll see ATU for a few seconds during
TUNE, followed by the power output (e.g. P2.0). Tapping any switch
will cancel TUNE and flash the SWR (e.g. r1.0). If no ATU is
installed, the display will show tun, since the KX1 itself does notinclude power metering. You'll still need to tap a switch or the keyer
paddle to exit TUNE mode even in the non-ATU case.
B AN D + R I T

DISP: Selects display mode

Selects frequency (nor), S-meter (bargraph), or battery voltage(BAT) display mode. In S-meter mode, the frequency is re-displayedwhenever the VFO is moved. S-meter mode functions as Frequency
Announce mode if audible CW feedback is enabled (page 67). Battery
display mode can be used during transmit or receive; in transmit mode,
it overrides the bargraph or TUNE display.
The remaining switch combinations are described in the Advanced
Operating Features section:
MENU + RIT

CW/LSB/USB receive mode (page 66)

RIT

Turns RIT on/off. When RIT is on, the decimal point
will flash slowly. The VFO knob will then vary only
the receive frequency, in 20 Hz steps, +/- 5 kHz.

MENU + 10/100

Turns Switch CW on / off (page 68)

CLR

Zeros RIT offset When RIT is OFF, holding CLR for
two seconds starts scanning (page 66).

B AN D + 1 0 / 1 0 0

High-Priority memory (page 67)

RIT + 10/100

Locks/unlocks VFO (page 68)

10/100

Selects 10 or 100 Hz VFO steps

1 kHz

Selects 1 kHz VFO steps (5 kHz , USB/LSB modes)

ELECRAFT

65

Menu Functions
To access the menu, tap M E N U . You can then scroll through menu entries by rotating the VFO knob (see list below). Hold E D I T to display a menu
entry's parameter, then change the parameter using the VFO knob. (Note: PLY and RCL behave differently: there is no need to enter edit mode touse them. See table for details.) Tap M E N U to return to scrolling. Another tap of M E N U will return you to normal operation. Edit Shortcut: You canskip tapping M E N U and jump directly into editing the last-used menu entry by holding E D I T .
Menu Entry

STL
STP
T-R
RPT
INP

Sidetone Level

Usage Details
Tap B AN D and R I T to select display brightness (0-5 ).
VFO knob selects on-time (5 to 60 sec. in 5 sec. increments, or INF for infinite).
T h e r e a r e f o u r s id e to n e v o lu me le v e ls ( 0-3 ) . A F G A I N a l s o a f f e c t s s i d e t o n e l e v e l .

Sidetone Pitch

P itc h r a n g e is 500 to 700 Hz in 10 Hz steps. 600 Hz recommended to match BFO offset.

Transmit-Receive Delay

T h e T - R ( Q S K ) d e l a y c a n b e s e t f r o m 0 to 900 ms (20 ms recommended for casual operation).

Message Repeat Interval

S e t s C W me s s a g e a u t o - r e p e a t i n t e r v a l ( 0 to 255 seconds). See page 66.

Input Device Selection

IAB

Iambic ModeCFB

CW Feedback Control

S e l e c t Hnd (hand key or external keyer) or PDn / PDr (internal keyer, paddle norm./rev.).
With PDn selected, J3 "tip" is DOT and "ring" is DASH. PDr is the reverse.
With a two-lever paddle (e.g. Elecraft KXPD1), you can use iambic keying; holding both paddles repeats a
DOT-DASH or DASH-DOT pattern. This can improve sending efficiency.
Mo d e A ( d e f a u l t ) h a s mo r e f o r g i v i n g t i mi n g a n d i s similar to Curtis keyer IC mode A.
Mode B is similar to Super CMOS Keyer III mode B.
10 -40 WPM or OFF . When CW feedback is on, audio Morse code is sent in response to all switch or menu
activity, and S-meter mode provides freq. announcements during VFO movement (page 67).

SIG

S-Meter Scale and Zero Set

LED

Description
LED Display Control

BFO
DDS
B30/B80

BFO Calibration

Zero parameter range is 30 -99 , adjusted using VFO knob. Set for zero-bars indication in S-meter mode withno signal. Scale parameter range is 2 -6 , adjusted by tapping B AN D and R I T . With approx. S9+20 dB
signal injected, adjust for 6 bars.
Sets BFO calibration offset, +/- 0.99 kHz. See page 68.

DDS Calibration

Sets DDS frequency reference scaling, +/- 99 PPM (parts per million). See page 68.

30/80 m Band Enable

BAT
ATU
RCL/STO

Low-Battery Voltage Set

Set to ON if KXB30 option is installed; covers 30 m and improves 49-m SWL reception (page 71). Tap 1 toselect B30 , or 2 to select B80 . Set B30 to ON if either the KXB30 or KXB3080 option is installed. Set
B80 to ON if the KXB3080 is installed. Otherwise both should be set to OFF .
Sets the low-battery warning threshold voltage (see page 62 for recommendations).

Freq. Memory Recall/StoreSee KXAT1 manual. If the antenna tuner option is not installed, parameter appears as "--- ".
To recall, tap 1 , 2 or 1 0 / 1 0 0 . To store, hold E D I T to switch to STO , then tap 1 , 2 or 1 0 / 1 0 0 .
One memory can be assigned as the High-Priority memory for quick recall (see page 67).

PLY/RECCW Message Play/Record

To play, tap 1 or 2 . To record, hold E D I T to switch to REC , then tap 1 or 2 . Auto-repeat: see page 66.

ATU ModeELECRAFT

66

Advanced Operating Features

Receive Mode Selection (CW, LSB, USB)

Recording and Playing CW Messages

The KX1 provides three receive modes: CW (nor or "normal"),
LSB, and USB. Hold M E N U + R I T to select the desired mode.

The KX1 provides two message memories of 48 bytes each. CW
messages can only be recorded using the KX1’s internal keyer.
Set INP to PDn or PDr to use the internal keyer.
To Record: Tap M E N U and locate the PLY menu entry, change it toREC by holding E D I T , then tap either 1 or 2 . The display will show
048, indicating that 48 bytes of storage are available in this buffer.
This number will count down toward 0 as long as you are sending.
Whenever you stop sending completely, up to two standard-length
word spaces will be inserted. To stop recording, tap any switch. If you
do this before starting to send, the original message contents will bepreserved.
To Play: Tap M E N U and locate the PLY menu entry, then tap either
1 or 2 . Message play can be canceled at any time by hitting any key orby tapping the keyer paddle. You can also change the keyer speed
while messages are playing using the VFO knob.
To use Auto-Repeat: Locate the PLY menu entry as before, but thenhold either 1 or 2 . The message will then play back continuously until
you tap another switch or hit your key or paddle. You'll see RPT on
the display between message transmissions.
Setting the Auto-Repeat Interval: The length of the pause between
messages during auto-repeat can be programmed using the RPT menu
entry (0-255 sec.). Long delays are useful for beacons.
Keyer Test Mode: To play back messages without transmitting, use
keyer test mode. In this mode, you'll see P=0 on the LED during
message play, rather than the transmit bargraph. To turn keyer test
mode on/off, locate the PLY menu entry, then tap the VFO knob.
You'll see P=0 and nor on alternate taps.

In CW (nor) receive mode, LSB is used on 40 meters, and USB isused on 30 and 20 meters. In this mode a CW offset is introduced onreceive, which means that you must match received-signal pitch toyour sidetone pitch to determine a station's carrier frequency. CW
mode also provides a 1 kHz fast VFO tuning rate, compatible withham-band tuning.
LSB and USB receive modes have no receive CW offset, so the
VFO will show a station's carrier frequency when a voice signal istuned in properly (SSB) or when a carrier is zero-beated (AM or CW).
The required CW offset is instead introduced on transmit. These
modes also provide a 5 kHz fast VFO tuning rate, useful for tuning
SWL band segments.
Cross-mode (CW/SSB) operation: Cross-mode contacts can be madein all three of the KX1's receive modes, without the need to use RIT.
When an SSB signal is correctly tuned in, and you transmit, the SSB
station will hear you at about a 600-Hz pitch.
Receiver performance considerations: Several strong internallygenerated signals can be heard outside of the ham bands7. If one ofthese signals falls near an AM signal of interest, try switching
sidebands to reduce interference. Note: on 20 meters, USB and nor(CW) receive modes provide somewhat better sensitivity than LSB
mode. See Circuit Details for an explanation.

7

These signals originate either at the DDS or from mixing products, and are
typical for a superhet receiver using a low I.F. Strong signals appear at thefollowing frequencies, in kHz, with the applicable sideband shown inparentheses: 5895 (USB), 6141 (USB), 6358 (LSB), 6550 (USB), 7989
(LSB), 9148 (both), 9826 (both), 14740 (both), 14981 (both). Additional
weak signals can also be heard, but in general will be masked by band noise.

ELECRAFT

67

Scanning:

Audible CW Feedback on Switch Press

To set up scanning, use the STO menu function to save scan start/end
points in frequency memories 1 and 2 (for each band). Now, whenever
RIT is off, you can activate scanning by holding CLR for two
seconds. Scanning is “live” (not muted). It can be stopped by tapping aswitch, turning the VFO, or transmitting. If the VFO is set for 10 or
100 Hz steps, scanning proceeds at 100 Hz per step. If the VFO is set
for fast tuning, scanning uses 1 kHz steps (if the receive mode is LSB
or USB, 5 kHz steps are used outside ham bands).

When CW feedback is turned on, audio Morse code will be sent inresponse to all KX1 controls, when using the menu, etc. This is usefulwhen the display cannot be used, such as in very bright sunlight orwhen eyes-free operation is required. Speeds from 10 to 40 WPM canbe selected, in 5-WPM steps.

Using Frequency Memories
Three frequency memories are available on each band, accessed using
the RCL (recall) menu entry. In addition to VFO frequency, thereceive mode (CW/LSB/USB) is saved on a per-memory basis.
Any one memory can be designated as High-Priority when it isstored, as described below. This allows you to quickly switch to one
often-used memory—such as WWV or a net—and back.
To store: First tap M E N U and scroll to the RCL menu entry (memory
recall). Hold E D I T to change the menu entry to STO (store), then tap
1 , 2 , or 1 0 / 1 0 0 (VFO knob). The display will flash 1, 2, or 3 inresponse. However, if you hold rather than tap the switch that selects
the memory, that memory will become the high-priority memory, andthe display will instead flash 1H, 2H, or 3H. Exit the menu.
To recall: Tap M E N U , locate RCL, then tap 1 , 2 , or 1 0 / 1 0 0 . The
recalled frequency and mode will be displayed. Exit the menu.
Switching to the High-Priority memory: First, press and hold B AN D
+ 1 0 / 1 0 0 , which will switch to the high-priority memory, if one has
been assigned. The stored receive mode will be used, and if the bandchanged, the ATU L/C values will also be recalled. If desired, you canthen restore your original band and frequency by holding B AN D +1 0 / 1 0 0 again. Exception: If you tap B AN D or change receive modesin the interim, the restore operation will be cancelled, and the KX1will remain on the new band.

To turn on CW feedback on switch press: Either (1) set the CFB
menu parameter to the desired CW feedback speed; or (2) hold the
M E N U , B AN D , or R I T switch down at power-on, which forces CFB
to 10, 20, or 30 WPM respectively. This also sets the LED to
maximum brightness and reports the firmware revision (on the display
and in CW).
Differences between LED display and CW feedback:1. All zeros are converted to long T's, and decimal points are sent as
R (a CW standard, derived from the word "radix"). In the DDS
and BFO menu entries, the minus sign (-) is sent as N. For
example, a BFO parameter of -.16 would be sent as NR16.
2. Some 3-letter text strings are reduced to a single letter. These
include RIT on (R), RIT off (O), RIT clear (C), VFO lock (L),VFO unlock (U), nor/LSB/USB receive modes (N, L, U), andnor/announce/batt display modes (N, A, B). "Frequency
Announce" display mode (A) is discussed below.
3. When using the menu, you can scroll quickly past menu entries if
desired, which will truncate sending of associated text in CW. The
PLY (Play) menu entry is truncated to P.
4. The VFO frequency can be checked at any time by tapping BAND
once. The frequency will be announced in MHz and kHz, prefixedby U or L in USB or LSB mode, and followed by R if RIT isturned on. The kHz part of the frequency, and R for RIT if
applicable, is also sent when you select the fast tuning rate.
5. Frequency Announce display mode provides audible "tics" every
10 VFO steps, and reports the kHz digits every 100 VFO steps(i.e., every 10 kHz if 100-Hz tuning is selected). This is useful forfinding a specific frequency. The "tic" sound is a low tone, high

ELECRAFT

68
tone, or low/high tone (for 10 Hz, 100 Hz, and 1 or 5 kHz VFO
steps, respectively). Frequency Announce mode is turned on in thesame was as S-meter mode (hold the DISP switch combination,
B AN D + R I T ). When you select announce mode, AF (forannounce frequency) will be displayed, and the letter A will besent in CW. Holding the DISP switch combination again willswitch to battery display mode (B) and back to normal mode (N).

Switch CW: Sending CW using Front-Panel Switches
In an emergency, the B AN D switch can be used as a hand key, or the
B AN D and R I T switches can be used as a keyer paddle. To enable thisfeature, first use the INP menu entry to specify hand key (HND) or
one of the paddle modes (PDn / PDr). Next, press and hold the
M E N U switch and 1 0 / 1 0 0 simultaneously to toggle Switch CW on
and off. You’ll see btn (“button”) when switch CW is on, and Pdl(“paddle”) when it is off.
When switch CW is enabled and INP is set to HND (hand key), thenormal functions of the B AN D / W P M switch are not available. In
addition, if INP is set to PDn or PDr, the functions of the R I T /C L R switch are not available. To use the normal functions of theseswitches, turn off Switch CW mode as described above.

VFO Lock/Unlock
Holding RIT + 10/100 locks (LOC) or unlocks (nor) the VFO knob.
When the VFO is locked, rotating the knob will have no effect on the
VFO frequency or RIT offset, and tapping or holding the knob will notchange the tuning rate. The knob can still be used for changing the
CW keying speed or accessing the menu.

Operating Frequency Calibration
The KX1's VFO display accuracy should be about +/- 200 Hz without
calibration. Using the BFO and DDS calibration procedures below,
you can improve accuracy to typically +/- 10 Hz.
Before calibration, the KX1 should be turned on and allowed tostabilize at room temperature for 15 minutes.

BFO Calibration: This procedure compensates for the difference
between your BFO frequency and the nominal value (4913.00 kHz).
1. Select 40 or 30 meters, LSB receive mode.
2. In the menu, set BFO to .00, and DDS to 00. Exit the menu.
Tune in a strong station at a known frequency as accurately as
possible. You can zero-beat an unmodulated carrier (tune for 0 Hz
audio pitch), or tune in an AM broadcast or reference station such as
WWV. Write down the frequency shown on the dial.
4. Switch to USB, re-tune the signal, and write down this frequency.
5. Subtract the lower reading from the higher reading, then divide theresult by two. Example: USB = 10000.10 kHz, LSB = 9999.90
kHz. Subtracting LSB from USB leaves 0.20 kHz, and dividing by
2 yields 0.10 kHz. This is the BFO correction.
6. If the LSB reading was the lower of the two, set the BFO menu
parameter to the BFO correction value (in this example, .10). If theUSB reading was the lower one, set the BFO parameter to thenegative of the correction (in this example, -.10).
7. Exit the menu. You should now be able to switch between LSB andUSB receive modes without re-tuning the VFO.
DDS Calibration: This procedure compensates for any error in the
50-MHz reference oscillator. The BFO calibration procedure, above,
must be performed first.
1. Select 40 or 30 meters and LSB or USB receive mode. Don't
use CW (nor) mode, as this introduces a receive offset.
2. Tune the VFO to the exact specified frequency of a reference
signal. Example: For WWV at 10 MHz, you must tune to exactly
10000.00 kHz as indicated on the KX1's display. You might startwith 5 kHz steps (hold the VFO knob), but then switch to 100 Hz
and finally 10 Hz steps as you get closer (by tapping the knob).
3. Edit the DDS menu parameter. While listening to the reference
signal, use the VFO knob to adjust the parameter so that the signal
is properly tuned in. If it is an unmodulated carrier, tune for zero-

ELECRAFT
beat (0 Hz audio). If it's a voice signal, tune for most naturalsounding audio. Then exit the menu.

Checking the Firmware Revision
Hold any switch on power-up to display the revision (e.g. 1.01).
Note: Checking the firmware revision by holding M E N U , B AN D , or
R I T on power-up also sets the LED to high brightness and enables
CW feedback on switch press (at 10, 20, and 30 WPM respectively). If
you turn the KX1 back off before accessing the menu, the LED
brightness and CW feedback will revert to their previous settings.

69

Resetting to Factory Defaults
Reset to defaults takes two steps. Step 1: Hold B AN D and M E N U
together on power-up, releasing the switches after the LED test. You
should see E09. Step 2: Turn power off and back on again; youshould see E10. Tap any switch. You'll then need to set up all menu
entries again.

ELECRAFT70

QRP Operating Tips

SWL (Shortwave Listening) Tips

Antennas: When you're using low power, a good antenna and groundsystem can make a big difference. There are many references onantennas available, including the ARRL Antenna Handbook.

Tuning Range: The KX1 can tune a wide range on each band:

QRP Frequencies: Low-power enthusiasts can be found at certain"watering hole" frequencies on each band, listed below (kHz). An
asterisk (*) indicates European or alternative QRP frequencies.
80 m:

3560

40 m:

7040 (*7030)

30 m: 10106 (*10116)
20 m: 14060
Calling and Listening: Calling CQ with low power may befrustrating unless you have a very good antenna. Expect to spend far
more time listening. Keep transmissions short, especially whenworking other QRP stations, which will often be at or even below thenoise level. Narrower filters (less than 500 Hz) and slower code speeds(less than 20 WPM) should be used when conditions are marginal.

80 m: 1-5.5 MHz
40 m: 5-9.5 MHz
30 m: 8-12.5 MHz
20 m: 12-16.5 MHz
The 80 meter and 30 meter frequencies are available when the optional
KXB3080 (30 m and 80m) or the KXB30 (30 m only) modules are
installed.
The useful tuning range is actually somewhat smaller, since signals
will fall off as you tune outside the ham bands (note the exception tothis described in the next paragraph).
Using the KXB30 or KXB3080 on 30 and 40 meters: If you have the
KXB30 or KXB3080 option installed, you'll be able to use theassociated ham bands and receive nearby SWL segments. But thisoption has another important function: its tuning capacitors will beturned on automatically on 40 meters if you tune below 6.7 MHz. Thisre-resonates the band-pass filter at about 6.2 MHz, greatly improving
sensitivity in the popular 49-meter SWL segment (5.9-6.4 MHz).
Tuning AM or SSB signals: The FILTER control should be set fully
clockwise when listening to broadcast stations. While you can listen to
AM or SSB stations in any of the KX1's three receive modes(CW/LSB/USB), LSB or USB provide two advantages: elimination of
the CW receive offset, and 5 kHz rather than 1 kHz tuning steps. You
can use 10-Hz steps to fine-tune (zero-beat) AM signals.
Frequency Memories and High-Priority Memory: Commonly-used
SWL frequencies can be store in frequency memories. If you often
switch to a time reference such as WWV (at 5, 10, or 15 MHz), you
can designate the associated memory as high-priority for quick access(see page 67).

ELECRAFT71

KX1 Options
30-Meter Module (KXB30)

Automatic Antenna Tuner (KXAT1)

The KXB30 adds 30 meter coverage to the KX1, and also greatly
increases receive sensitivity in the 5.9-6.4 MHz SWL segment (with40 m selected). 30 meters is an excellent band for day and night
operation and is popular with QRPers. Being a WARC band, it is offlimits for contests, and is thus a haven for those not interested incontest operation. WWV or WWVH provide universal coordinatedtime announcements at 10.000 MHz, and many AM broadcast stations
can be heard in the 9-10 MHz band.
The B30 menu entry must be set to ON to use the 30-m band.

With the KXAT1 internal automatic antenna tuner installed, you canconnect unbalanced, random-length antennas directly to the KX1. (Aninexpensive home-made balun can be used with balanced lines.) In
many cases the ATU will provide a 2:1 or better match on all bands.
Once you've tuned up an antenna, the tuner's L and C settings will berecalled instantly when the band is changed.

30 and 80-Meter Module (KXB3080)
The KXB3080 adds both 30 meter and 80 meter coverage to the KX1.
Like the KXB30, the KXB3080 also greatly increases receive
sensitivity in the 5.9-6.4 MHz SWL segment (with 40 m selected).
When 80 m is selected, the tuning range is increased from 1.0 to 5.5
MHz.
The B80 menu entry must be set to ON to enable both the 30 m and80m bands when the KXB3080 module is installed.

Plug-In Keyer Paddle (KXPD1)
The KXPD1 paddle offers a rugged, lightweight alternative to
traditional keyer paddles or hand keys. It plugs directly into the frontof the KX1, and is ergonomically designed for operating comfort. The
KXPD1 is retained by a thumb screw to prevent movement during
keying, and can quickly be reversed for left- or right-handed operation.

The KXAT1 provides SWR and power information for the KX1
display in TUNE mode. Also, during normal keying it provides anindication of power output on the LED bargraph (1 bar per 0.5 watts).
Without the ATU installed, the KX1 displays tun in TUNE mode and1 bar during keying.

72

ELECRAFT

Circuit Details
While reading this section, refer to the Block Diagram (Appendix C)
and schematics (Appendix B).
Receiver: The receiver is a single-conversion superhet, using downconversion to a low intermediate frequency (I.F.) of about 4.915 MHz.
Down-conversion minimizes complexity and receive-chain noise,
while the low I.F. allows adequate CW selectivity with a variablepassband, 3-pole crystal filter. The use of active mixers keeps current
consumption low, compatible with portable operation.
DDS VFO: The VFO is based on a low-power DDS (direct digitalsynthesis) IC. A crystal oscillator provides the reference signal for the
DDS, ensuring excellent frequency stability over a wide temperature
range. While a DDS-based VFO does not offer the same signal purity
as an L-C VFO or PLL synthesizer, it is a good choice for a portablestation that will most often be used by a single operator well removed
from strong nearby stations. It is also extremely frequency-agile,
allowing coverage of both ham bands and SWL bands. The unit
chosen (AD9834) requires a minimum of components and draws only
5 to 8 milliamps.

The DDS output is filtered by low-pass filter L4/L5/C50-52. In orderto provide adequate roll-off of non-harmonic spurs about 14 MHz
when operating at 40 meters, the filter's knee is set just above the 20-mband edge. Because of this, LSB receive mode on 20 meters is lesssensitive; LSB on this band requires a mixer injection frequency of
4.9+14 = 18.9 MHz, which is significantly attenuated by the DDS
filter.
Transmitter: On transmit, the DDS outputs the actual carrier
frequency, so no transmit mixer stage is required. Q1, Q4 and Q5 forma 3-stage buffer for the DDS signal. Maximum power output from thefinal stage (Q6) is about 4 to 5 watts, depending on the supply voltage.
Q7, in the receive band-pass filter, limits the signal voltage that canreach the receive mixer when the rig is in transmit mode.
Microcontroller: A low-power microcontroller (U1, MCU) is used tocontrol the transceiver and handle user interface elements, such as thedisplay and switches. The MCU communicates with the optional
KXAT1 ATU on the VFWD/DATA line at about a 2 kHz data rate.
U1 runs at just below 4 MHz to avoid band-edge spurs.
The KXAT1 provides SWR and power information for the KX1
display in TUNE mode. During normal keying, it provides an accurate
indication of power output (1 bar per 0.5 watts). Without the ATU
installed, the KX1 displays only a qualitative power output indication(see page 64).

ELECRAFT

A1

Appendix A - KX1 Parts Listi

Many parts are static-sensitive, including parts pre-mounted on the circuit board. Wear a grounded wrist strap or ground yourself
frequently while handling. Do not handle more than necessary. Do not remove parts with leads in black foam from the foam until they are
installed.
Photo

Reference Designator

Description

C5,C8,C11,C12,C16,C17,
C18,C21,C31,C39,C43
C3,C6,C9,C15,C22,C30,
C32,C33,C34,C37,C41,
C42,C55
C48, C49
C46
C14
C47
C27
C51
C45
C56
C13, C54
C50
C2, C4, C24, C25
C52
C1

Quan.

Part No.

Capacitor, 0.1 µF, 0.1" LS (104)11E530020

Capacitor, .01 µF, 0.1" LS (103)13E530019

Capacitor, 1000 pF C0G, 5%, 50 V, 0.1" LS (102)
Capacitor, 470 pF C0G, 5%, 50 V, 0.1" LS (471)
Capacitor, 330 pF, C0G, 5%, 50 V, 0.1" LS (331)
Capacitor, 220 pF C0G, 5%, 50 V, 0.1" LS (221)
Capacitor, 150 pF C0G, 5%, 50 V, 0.1" LS (151)
Capacitor, 100 pF, C0G 5%, 50 V, 0.2” LS (101)
Capacitor, 68 pF, C0G, 5%, 50 V, 0.2” LS (68, 680)
Note: C56 is also 68 pF, but has 0.1” lead spacing.
Capacitor, 68 pF, C0G, 5%, 50 V, 0.1" LS (68, 680)
Capacitor, 56 pF, C0G, 5%, 50 V, 0.1" LS (56, 560)
Capacitor, 39 pF, C0G, 5%, 50 V , 0.2” LS (390, 39)
Capacitor, 27 pF C0G, 5%, 50 V, 0.1" LS (27, 270)
Capacitor, 22 pF C0G, 5%, 50 V, 0.1" LS (22, 220)
Capacitor, 4.7 or 5 pF C0G, 5%, 50 V, 0.1" LS (4.7)

2
1
1
1
1
1

E530072
E530004
E530147
E530042E530049
E5300341

E530007

1
2
1
4
1
1

E530150E530146
E530036
E530141
E530017
E530048

ELECRAFT
Photo

A2
Reference Designator

Description

Quan.

Part No.

C26

Capacitor, 120 pF disc (121)1

E530041

C19, C44

Capacitor, .022 µF, 50 V (223)2E530056

C7
C23,C35
C10,C20,C38,C53

Capacitor, 220 µF electrolytic
Capacitor, 100 µF electrolytic, low-profile
Capacitor, 10 µF electrolytic, low-profile

1
2
4E530046
E530149
E530045

CA,CB

Capacitor, trimmer, 5-20 pF, bottom adjust (red)2

E540004

CC

Capacitor, trimmer, 8-50 pF, bottom adjust (brown)1

E540005

D1

LED, White, T1-3/4 size

1

E570014

D2, D3

Diode, Shottky, 1N5817

2

E560008

D5, D6

Diode, varactor, 1SV149

2

E560005

D4

Diode, switching, 1N4148

1

E560002

D7

Diode, 47 V zener, 1N4756A

1

E560013

DS1

LED display, 3 digit, 7 segment

1

E570013

ELECRAFT

A3
Photo

Reference Designator

Description

Quan.

Part No.

J1

Conn., DC barrel

1

E620026

MISC

Mating connector for J1

1

E620032

J2

Conn., BNC, R.A. PCB mount, no bushing1

E620075

J3

Conn., 1/8" stereo jack1

E620027

MISC

Miniature three-circuit plug that mates with J3

1

E620033

J4

Conn., 1/8" stereo jack with switch

1

E620028

J5

Conn., 2-pin female housing, 0.1" spacing, forinternal battery

1

E620021

ELECRAFT
Photoi

Do not mix thesewith resistors. Keep themin their own envelope
until installed.

A4
Reference Designator

Description

Quan.

Part No.

MISC

Crimp pins for J5, package of 2

2

E620022J6

Conn., 5-pin female, 0.1" spacing

1

E620051

J7

Conn., 3-pin female, 0.1" spacing

1

E620009

J8

Conn., 2-pin female, 0.1" spacing

1

E620066

K1,K2

Relay, DPDT

2

E640010

L1,L2

Toroid on T37-6 core (Yellow): #26 enamel; L1 13t;
L2 14t (See text for winding instructions)2

E680013

L3

Inductor on FT37-43 core (Black):
6T #26 (See text for winding instructions)1

E680003

T1

Transformer wound on FT37-43 core (Black), 8T:2T#26 (See text for winding instructions)1

E680003

1

E6900441

E6900421

E690036

L6
L7
L4mini (larger size) RF choke, 6.8 µH (blu-gry-gld)
Note: L6 may be physically larger than L7 in somekits. This is normal.
mini (larger size) RF choke, 4.7 µH (yel-vio-gold)
micro (smaller size) RF choke,
2.2 µH (red-red-gold)

ELECRAFT

A5
Photo

Reference Designator

L5
L8
L9
L10

Description

mini (larger size) RF choke,
5.6 µH (grn-blu-gold)
micro (smaller size) RF choke,
18 µH (brn-gry-blk)
micro (smaller size) RF choke,
100 µH (brn-blk-brn)micro (smaller size) or mini (larger size) RF choke,
33 µH (org-org-blk) Note: When color coded, either
or both orange bands may appear to be brown.

Quan.

Part No.

1

E6900371

E6900401

E6900131

E690041

P1

Connector, 2-pin male with locking ramp, 0.1"
spacing, for internal battery

1

E620024

Q1, Q2, Q3

Transistor, JFET, J309 (309)3E580009

Q4, Q7, Q8, Q9Transistor, NPN, 2N4124

4E580006

Q5

Transistor, NPN, 2N3904

1

E580017

Q6

Transistor, NPN power 2SC5739 (plastic tab) or
2SC2166 (metal tab)

1

E580007

R1,R3

Pot, 1K linear, panel mount, no bushing2

E520013R2

Pot, 10K linear, panel mount, no bushing1

E520014

ELECRAFT
Photo

A6
Reference Designator

Description

Quan.

Part No.

R4

Pot, 100 ohm trimmer

1

E520008

R18
R15
R13,R24,R29,R32
R8,R12
R5
R21
R19, R28
R16,R17,R20,R31
R23
R9,R22
R6,R7

Resistor, 3.3M, 1/4 watt, 5% (org-org-grn)
Resistor, 1M, 1/4 watt, 5% (brn-blk-grn)
Resistor, 22K, 1/4 watt, 5% (red-red-org)
Resistor, 6.8K, 1/4 watt, 5% (blu-gry-red)
Resistor, 4.7K, 1/4 watt, 5% (yel-vio-red)
Resistor, 2.7K, 1/4 watt, 5% (red-vio-red)
Resistor, 1.8K, 1/4 watt, 5% (brn-gry-red)
Resistor, 1K, 1/4 watt, 5% (brn-blk-red)
Resistor, 470 ohms, 1/4 watt, 5% (yel-vio-brn)
Resistor, 300, 1/4 watt, 5% (org-blk-brn)
Resistor, 200 ohms, 1/8 watt, 5% (red-blk-brn)

1
1
4
2
1
1
2
4
1
2
2

E500021
E500024
E500090
E500115
E500047
E500005
E500004
E500013
E500003
E500023
E500114

R10,R14,

Resistor, 47, 1/4 watt, 5% (yel-vio-blk)

2

E500019

R26,R27, R30
R11,R25

Resistor, 22, 1/4 watt, 5% (red-red-blk)
Resistor, 10 ohms, 1/4 watt, 5% (brn-blk-blk)

3
2

E500028
E500054

RP1

Rpack, 390 ohms, 8R, 16 pins (391)1

E510023

RP2

Rpack, 1K, 5R, 6 pins (102)1

E510024

RP3,RP4

Rpack, 10K, 5R, 10 pins (103)2E510025

RP5

Rpack, 100K 5R, 10 pins (104)1

E510026

ELECRAFT

A7
Photo

i

Reference Designator

Description

Quan.

Part No.

S1,S2

Slide Switch, SPDT, PCB mount, 0.5A @ 50V

2

E640015

S3,S4,S5

Momentary contact. switch, 6mm

3E640016

MISC

Keycap, square, blue, 6 mm

3E640017

U1

IC, MCU, KX1, PIC16F876A (E600075)

1

E610017

U2

IC, DDS, AD9834, SMD

1

E600076

U3

IC, TC4427, dual driver1

E600077

U4

IC, LM386N-1, AF amp

1

E600022

Handle with care
– ESD Sensitive.

Pre-installed on boardiHandle with care
– ESD Sensitive.

ELECRAFT
Photo

Pre-installed on boardi

A8
Reference Designator

Description

Quan.

Part No.

U5,U6

IC, NE602 or NE612 mixer

2

E600006

U7

IC, TPS76427, 2.7V reg, 5-PIN, SMD

1

E600078

IC, 78L05, 5-V regulator

1

E600029

U9

IC, 77L06, Low dropout 6-V regulator

1

E600079

X2-X5

Crystals, 4.9136 MHz, matched set of 4 (using p/n
E660000)

4

E850162

X1

Crystal, 3.995 MHz, low profile, HC49/US

1

E660020

Z1

Encoder, 80 Counts, w/PB switch

1

E640018

Z2

Oscillator module, 50 MHz, SMD

1

E660021

HDWR

Shoulder washer

1

E700001

Handle with care U8– ESD Sensitive.

Pre-Installed on Board

ELECRAFT

A9
Photo

Reference Designator

Description

Quan.

Part No.

MISC

Battery holder, 3 AA cells

2

E980071

HDWR

Screw, 2-56 x 1/8" Panhead Phillips, black(2 spares)

6

E700084

HDWR

Standoff, 4-40 x 5/16" long, 3/16" dia., hex,
Male-Female2

E700083

HDWR

Standoff, 4-40 x 3/16" long, 3/16" dia., hex,

1

E700068

HDWR

Standoff, 4-40 x 3/4" long, 3/16" dia., hex

2

E700085

HDWR

Split lock washer, #4 (2 spares)

6

E700004

HDWR

4-40 x 5/16" thumbscrew, black oxide

2

E700050

HDWR

Screw, 4-40 x 1/4" undercut flat-head Phillips, black(2 spares) Note: If your kit has a 2SC2166 (metal tab)for Q6, one screw will be nylon (part number
E700092). Use the nylon screw for mounting Q6 as
described in the assembly procedure.

5

E700082ELECRAFT
Photo

A10
Reference Designator

Description

Quan.

Part No.

HDWR

Screw, 4-40 x 3/16" pan-head Phillips, black

1

E700015

MISC

Rubber foot, self-adhesive

3

E700024

KX1 top cover

1

E100172

MISC

KX1 bottom cover

1

E100173

MISC

Wire, #26 red enamel

MISC

Wire, #26 green enamel

MISC

Knob, 1.15" dia.

1

E980072

MISC

Red plastic filter w/two adhesive strips (Packaged
with serial number label and thermal pad in a smallenvelope).

1

E980073

MISC

IC socket, ultra-low-profile, 28 pins

1

E620074MISC

6’E760002(1.8m)
3’
E760004(0.9m)ELECRAFT

A11
Photo

i

Reference Designator

Description

Quan.

Part No.

MISC

Large Allen wrench, MSC 05471057 5/64”

1

E980004

MISC

Sandpaper1

E850090MISC

KX1 PCB w/pre-mounted parts (U2, U7, Z2); Empty
PCB is Part No. E100174

1

E850163

MISC

Thermal pad (Normally shipped in the same envelopewith the Serial Number label).

1

E700002

MISC

Heat-shrink tubing

MISC

Serial number label

Handle with care
– ESD Sensitive.

6”
(15.3
cm)
1

E980037
E980024

100K

6

RP5 5

8

7

11 6

1

16 1

4

13 4

2

15 16

7

10 7

3

14 3

DIG1

RP3
10K

B
C

7

13

COLON

C12
0.1

VBATT

VFWD/DATA

9

D
E

5

DIG2

VBATT

G

RP3
10K

DP
5

DS1
Common-Cathode

RB6

RA1

RB5

RA2

RB4

RA4

RB2

VSMTR

RA5

RB1

VSS

RB0

OSC1

VDD

OSC2

VSS

R13 2 2 K

RC0

RC7

R12 6.8K

RC1

RC6

C24
27

B

10

2

nc

2
3

Z1 (ENC)

6V

RC2/FSYNC

C55
.01

SCK

**

1

RF Gain

K1B

C56
68

CC
50

6

C15
.01

7

U6

R19
1.8K

X3

50 MHz

4

3

Vcc

OUT

STBY GND
2

2.2µH

C14
330

AF Amp

16
15/FSYNC
14
SCLK
13
SDATA
12
SLEEP
11
RESET

1

R25
10
C21
0.1

R5
4.7K

nc

J4

AF GainC53
10uF

Phones/Spkr

C54
56

RX ANT

L3

0.1
T1

6

9

5

R24
22K

Q5
2N3904
R4
100

C34
.01

2N4124
3

7

RP4
10K

C45
68

C47
220

C46
470

C48
1000
4

Q6
2SC5739 OR 2SC2166

RF OutQ4

D7
1N4756A
47 V

R30
22

1

3

2

K2A

47

C41
.01

*
**

= Surface-mount device.
= 30-meter module connections

J2
Ant.

6

K2B
7

= On bottom of PC board.
R10

J8
Gnd

J7
ATU

5

10
R27
22

2

C49
1000

PA

R11
8

4
1

L2

3
1

10

L1

C44
0.022

R9
300

200

2

6V

5

R3
1K

1K

C43

C42
.01

R6 R7

RP3
10K

D4
1N4148AGC
Q92N4124

4

2

6

C23
100uF

2

20

SIGN

OUT

22

C50
39

19
IOUT
18
AGND
17
Vin

V+

GND

C22
.01

7

U4

R20

6T_2
C35
100µF

IOUTB

IN2

8

C9
.01

6T

C51
100

DDS *

3

LM386N

Q3
J309

V+

SCK

1
FS ADJ
2
REF
3
COMP
.01 4
A Vdd
5
D Vdd
6
CAP
7
DGND
8
MCLK
9
FSEL
10
PSEL

G2

X5 4.913 MHz/FSYNC

2.7V
Z2

L4

1

G1

IN1 BYPASS

C18
0.1

R26

2

2

4

7

C13
56

R32
22K

R21
2.7K

3

C30

6

10µF

1

C19
.022

3.3M
U5
NE602

C8
0.1

3

U2
AD9834

C17
0.1

2

R8
6.8K

IN

+
C20

1

C37
.01
C31
0.1

nc

BYP

R15
1M

VSMTR

R31
1K

SDO

EN
GND

R29
22K

4

L10
33 µH

+

+

OUT

S1
Lamp
On/OffC2
27

0.6VDC @ max. signal

C52
22

L5
5.6µH

R23
470

+

5V

6T

5

V+

3

S

* U7

4

1

D5

D1
White LED

U9
77L06

R18

G

TPS76427
5

1

V-

D

14 MHz LPF

C38
10µF

C7
220µF

Q2

1.4VDC @ no signal

RX ANTC39
0.1

TC4427

C4
27

C26

**

K2

8

4.914 MHz

J309

B

U3

OUT
IN
GND

C10
10µF

5

OUTB

Crystal Filter

.01

120

K1

+

C3

K1A

7

V+

2

Q1
6

8

6

J309

L9
100 µH

1SV149

5

1

7

6V_2
L8
18µH

X4

D6

R28
1.8K

8

INB

RP5

4

X2

NE602

6T_2

CA
20

D

V3

GND

4

**

NC
OUTA

Product Det.
and BFO

100K

1

Q7
2N4124*

3100K

2N4124

5

3
2

*A *

SDO

C16
0.1

RP5

Q8
2

C27
150

3

NC
INA

/MUTE

2

L6
6.8µH

2

Bandwidth

4

S2
Power
On/Off

6V

1

4

V+

V+

1

8

CB
20

78L05

G

5

C1
5

C

L7
4.7µH

C5
0.1

S5

5V

20

P1

OUT
IN
GND

5V

6

7-14V DC

D2

C6
.01
U8

5

3

15

6V

R1
1K

**

Z1-SW

R2
10K

R14
47

J5

J1
D3

BT1

2

RC4

4

6V_2

C11
0.1

J6
Aux.

-

5

Rcv Mixer

VFWD/DATA

RP2
1K

S4
25

RC5

RC3

14

4

+

/MUTE

X1
3.995 MHz

1N5817

S3

28

+

1

RB3

R22 3 0 0

3

A

/MUTE

RA0

3

1

3-digit LED

C25
27

4

6

8

DIG3

RB7

RA3

5

F

MCLR

1

S

DP

6

12

C32
.01

C33
.01

S

G

9

B G C A E DP F D

16F876A

10

8

2

2

F

8

A

1

E

12 15

2

D

5

J3
Key/Paddle

R16 1 K

1

C

U1

+

B

5V

RP5

RP1 3 9 0
A

R17 1 K

MCU

D

9

D

10

G

RP5
V+

Elecraft

KX1 Transceiver

By W. BurdickRev.
B

E.Swartz

Date
Sht.
1 of 1
11/03/03

Low-pass Filter

Appendix B

LOW-PASSFILTERDDS VFO(U2)

BUFFER(Q1)

DRIVER(Q4, Q5)

BANDPASSFILTER

T-R
(Q7)

POWER
AMP
(Q6)

LOWPASSFILTER

WithVFO = 7000.00 kHz and
RX Mode = Normal (CW):
Fdds, RX = 11913.6 kHz
Fdds, TX = 7000.00 kHz

AGC
(Q9)

RCV
MIXER
U6)

MCU
(U1)

CRYSTALFILTERPROD.
DETECTOR
(U5)

A.F.
AMP
(U4)

4.9136 MHzDISPLAY
AND
CONTROLS

BFO
4.913 MHz

KEY
CommonTransmit

Receive

Appendix C

KX1 BLOCK DIAGRAM

W. Burdick/E. Swartz

Rev. A 10-04-00

Appendix D. KX1 Assembly Photographs

Assembled PC
board, top view

NOTE: The power transistor near the center at the top edge may have a black plastic or shiny metal tab.

Assembled PC
board, bottom view,
with top coverinstalled

Appendix E - Troubleshooting
KX1 TOP COVER REMOVAL: (1) Remove the three flat-head screws
that hold the PCB to the top cover. (2) remove the VFO knob. (3) Flex the frontedge of the top cover outward slightly while pulling upward gently on the key
jack. The key jack should pop out of its hole. (3) Lift out the PCB.
(!) NOTE: If you need to transmit with the top cover removed, Q6 will not havea heatsink. Turn the power control (R4) fully counter-clockwise to limit power
to 0.5 watt or less. To prevent damage to the PA transistor, limit transmit timeto 3 seconds keydown, 10 seconds key up.

KX1 TOP COVER INSTALLATION: (1) Place the top cover onto the
PC board. Align switch caps with their holes using a long tool inserted between
PCB and top cover. (2) Snap the key jack into its hole by pushing down gently.
(3) Secure the PCB to the top cover using three 4-40 x 1/4" flat-head screws.
(4) Install the VFO knob.

Troubleshooting Tables
There are five troubleshooting tables (listed below). Within each table,
problems are identified by 2-digit numbers for cross-referencing purposes. In
most cases you’ll know which table to look in based on the symptoms you
observe. If in doubt, start with the General Troubleshooting table. Some
problem identifiers have corresponding error messages (see above).
General Troubleshooting
Display and Control Circuits
VFO
ReceiverTransmitter and Keyer

00-19
20-39
40-59
60-79
80-99

General Troubleshooting (00-19)

General Troubleshooting ProcedureProblem
00 Unit appears to becompletely dead whenpower switch is turnedon (no display, no
audio); possible
smoke, hotcomponents, etc.

Look for your problem in the Troubleshooting Tables.
Closely examine PC boards for poor solder joints and incorrect, broken or
missing components.
Check voltages using the DC Voltage Table at the end of this section.

Error Messages







If you see a message such as E10 on the LED, look up the corresponding
entry in the Troubleshooting Tables. Error messages can usually be cleared bypressing any switch. However, the cause of the message should be investigatedbefore continuing to operate the transceiver.

01 LED problem
02 BAT LO
displayed

E-1





Troubleshooting Steps
Make sure your power supply is connected,
turned on, and not plugged in backwards
Check fuses; examine cables for open/short
If the top cover is removed, make sure you
don't have a screw inserted into the tab of the
PA transistor (Q6)—this will short the 12V
line
Measure the +6V and +5V regulated power
supply voltages (20)Check the MCU, U1 (26)
See control circuits (24)Battery voltage may be below the level set in
the BAT menu entry. Recharge the battery
as soon as possible.

03 No audio
05 Current drain isexcessive on receive
06 Supply voltage
drops when KX1 is on
07 Error in actual vs.
displayed frequency
08 Freq. drift or
instability
09 EEPROM
initialization pending
10 EEPROM wasjust initialized
15 END or P=0 isdisplayed on keydown

24 LED display
problem

See Receiver troubleshooting table (60)Check regulated voltages (20); look for acomponent that’s warm to the touch
Check receive-mode current drain (05)Battery not fully charged
See Operation section (CAL menu entry)

See VFO troubleshooting table (40)26 Possible MCU
problem

E09 on display: See Advanced Operating
Features, Resetting to Factory Defaults
You may see E10 one time on power-up, or
if you install a new version of the firmware.
All KX1 parameters are set to defaults.
END : TX out of range (see specifications)
P=0 : CW test mode (see PLY menu entry)

25 Relay Problem

21 General problem
with switches or
potentiometers
22 +6 V too low(< 5.7V)

23 +5V too low(< 4.7V) or +2.7V too
low (< 2.5V)



























29 AuxBus problem(no communication
with KXAT1 ATU)
30 EEPROM test #1
failed31 EEPROM test #2
failed32 EEPROM dataerror
33 Configuration dataor menu problem

Display and Control Circuits (20-39)
Problem
20 Regulated
voltage(s) incorrectTroubleshooting Steps
DC input voltage must be > 6.5V
Unplug KXAT1 ATU option and re-checkIf +6V is too low (< 5.7V) go to 22
If +5V is too low (< 4.7V) go to 23
If +2.7V is too low (< 2.5V) go to 23
Check switch resistance open/closed; RP2
may be in backwards
Check resistance of potentiometers
Remove KXAT1 ATU option and re-check
Inspect 6V path on the KX1 PC board
Check for U9 installed backwards
Lift other component leads on the 6V line asneeded to find cause of excess loading
Remove U1 from its socket
Check for U8 installed backwards
Check for U7 incorrectly installed (surface
mount--use magnifying glass)
Use techniques given for 6V regulator(above)

E-2

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






DS1 backwards; check for shorts to groundon each pin
MCU pin bent or broken (U1)
RP1 pin not soldered or shorted
Relays not soldered
Check relay coil resistance, pins 1 and 8
U3 (TC4427) defective or backwards (27)Check all DC voltages on U1
Make sure U1 is not backwards, has no bent
pins, and is seated firmly in its socket.
Check oscillator components (X1, C24, C25,
R22)
Also see (33) if you suspect an error in amenu parameter, etc.
Look for short at J6 pin 5, U1 pin 2, or
KXAT1-U1 pin 17
Check voltage on J6 pin 5 (see table)
If you E30 , E31 or E32 on the LED, oneof the EEPROM tests has failed. CW
memories cannot be used. Parameters will be
set to defaults, and band 1 will be selected.
Try a full reset (33)
U1 may be damaged or inserted backwards
If a menu parameter is out of range or can’t
be modified, EEPROM may need to bereinitialized. See Advanced Operating
Features65 AF amplifier notworking

VFO (40-59)
Problem
40 General VFO(DDS) problem;
frequency jumps or
drifts

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





41 Can't tune VFO (orRIT offset)
42 No DDS output






Troubleshooting Steps
Note: A small amount of DDS drift may
occur due to aging of components andheating/cooling of the cabinet
Check 14 MHz LPF components (L4, L5,
C50-C52) and buffer (Q1, R31)
Make sure supply voltage is above 6.5V
Check values of R8, R6, R7, RP4, RP3
Check 5V and 2.7V regulator output (23)Check installation of Z2 and U2 (both surface
mount--use magnifying glass)
VFO may be locked ( see Operation)
VFO or RIT offset may be at end of range
See 40, above
See 40

70 AGC or S-meternot working

Problem
80 General
Transmitter problem













62 Signal loss only on
one band










Use the STL menu entry to set a sidetone
level of 3 . If you hear a strong tone, the A.F.
amplifier (RF-U4) is probably working, andthe problem is likely to be with the mixer(RF-U6) or other RF board circuits.
Signal trace through the receive chain
backwards by touching a tool or wire tovarious points along the receive path
Check all DC voltages in the receiver
Inspect the A.F. amp circuits
Check R5, D4, C53, Q9, R20, C8, and L9 forincorrect values or unsoldered leads

Transmitter and Keyer (80-99)

Receiver (60-79)
Problem
60 Low (or no) audio
output from receiver,or general receivergain problem



Troubleshooting Steps
If you hear normal audio output on one band
but not all bands, see 62
Make sure you have headphones or speakerconnected; turn AF GAIN clockwise
Check the key jack for a short to ground
Make sure RF GAIN is fully clockwise
Re-peak the band-pass filters
Check for ground shorts in the LPF and BPF
If you don’t hear any “hiss” at the receiver
output, troubleshoot the AF amplifier (65)
Check the 6V regulator (20)Re-do alignment on affected band
Check the band-pass and low-pass filters andcrystal for this band
Check functioning of the relays (change
bands, then measure relay leads that shouldbe open or shorted for that band)
86 Power output is
low or zero










E-3

Troubleshooting Steps
If power output is too low, go to 86
If power output slowly increases during keydown, go to 88
If current drain on transmit is too high for the
given power level, go to 92
If the transmitter output power seems to beunstable go to 88
If the transmitter stops transmitting by itself
go to 90
If the keyer isn’t working properly, go to 95
Make sure the power-output control, R4, isset fully clockwise
If the top cover is removed, make sure you
don't have a screw inserted into the tab of Q6
Unplug the ATU (KXAT1) and insert ajumper between pins 1 and 3 of J7; connect adummy load at J2. If this solves the problem,
see the KXAT1 manual's troubleshooting
section.
Check power output when using a 50Ω
dummy load; if the output is correct on adummy load but not when using an antenna,
your antenna is probably not matched
You may have a short in the LPF or BPF or








an incorrect LPF component value
Check relays (25)
Examine T1, L3, L1, and L2 for poorlystripped leads
Check T1 for backward windings
Check all DC voltages in the transmitter (Q1,
Q4, Q5, Q6)
Signal-trace through the transmitter to findwhere signal is lost (using an RF probe)
Check for any components getting hot

88 Power output
fluctuates







90 Output power
drops to zero suddenly
92 Current drain toohigh on transmit



95 Keyer Problem






E-4

If you stay in key-down (TUNE) mode forseveral seconds, it is normal to see someincrease in power; this is due heating of the
final amplifier transistor.
If power goes up and down significantly
during normal keying, you may have apoorly-matched antenna OR you may havepower set too high for your battery or power
supply to handle; try reducing power or
replacing batteries
If the transmitter is unstable (oscillating)even when connected to a 50-Ω load, you
may have an incorrect component value or a
toroid-winding error (86)
If you have transmit power set too high foryour battery or power supply, the supply
voltage may drop so low on transmit that it
resets the MCU (U1); try a higher supply
voltage or fresh batteries
If there's no ATU installed, verify that J7(ATU connector) is bypassed with a jumper
between pins 1 and 3
You may have power set higher than the final
amplifier can achieve for a given load or
power supply voltage, resulting in overdriveof transmitter stages. Reduce power to see if
normal current drain is restored.
Damaged PA transistors or other components
could cause inefficiency in any stage of thetransmitter. Check all DC voltages andcomponents; signal trace if necessarily (86)
If the keyer is generally erratic whentransmitting and seems to get worse as power
is increased, you probably have RF leaking
into the keyline. Try bypassing your key with.001 µF capacitors; also try 100 µH RF
chokes in series with the paddle connections.
Seek a better antenna match
Improve your ground system

DC Voltage Table – Integrated Circuits
NOTES: Measurements were made with a 50-ohm dummy load connected and a supply voltage of 13 V. The 30- meter option
was installed (KXB30) and the ATU was removed (KXAT1). In general, your measurements should be within 10% of the values
shown. Pins NOT listed in the table should indicate 0.0 volts DC. Pins marked with (*) are hard to measure due to noise
pickup. Shaded areas show transmit-mode measurements (using TUNE).
Ref.
U1

Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

VDC
5.0
5.0
4.6
4.9
4.9
3.4
1.4
0.0
0.8
0.9
0.0
0.0
5.0
0.0
0.0
0.0
0.0

Ref.
U1

U2

Pin
18
19
20
21
22
23
24
25
26
27
28
1
2
3
4
5
6

VDC
0.0
0.0
5.0
5.0
5.0
4.9
5.0
5.0
4.7
5.0
5.0
1.15
1.18
1.41
2.69
2.69
2.69

Ref.
U2

U3

Pin
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1
2
3

E-5

VDC
0.0
1.32
0.0
0.0
0.0
0.0
0.0
0.0
2.5
n/c
n/c
0.0
0.32
0.32
n/c
0.0
0.0

Ref.
U3

U4

(n/c)
U5

Pin
4
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4

VDC
0.0
0.0
5.9
5.9
n/c
1.26
0.0
0.0
0.0
2.97
5.93
2.99
1.26
1.39
1.39
0.0
4.44

Ref.
U5

U6

U7

Pin
5
6
7
8
1
2
3
4
5
6
7
8
1
2
3
4
5

VDC
4.44
5.57
4.95
5.62
1.39
1.39
0.0
4.39
4.47
5.54
5.04
5.62
5.0
0.0
5.0
1.17
2.69

DC Voltage Table – Transistors and Diodes
NOTES: Measurements were made with a 50-ohm dummy load connected and a supply voltage of 13 V. The 30- meter option
was installed (KXB30) and the ATU was removed (KXAT1). In general, your measurements should be within 10% of the values
shown. Pins NOT listed in the table should indicate 0.0 volts DC. Pins marked with (*) are hard to measure due to noise
pickup. Shaded areas show transmit-mode measurements (using TUNE).
Ref.
D1
(on)
D2
D3
D4
D5
D6
D7

Pin
A
K
A
K
A
K
K
K
K
K

VDC
13.33
10.4
13.8
13.5
9.0
13.5
0.3*
5.8
5.8
13.5

Ref.
Q1
Q2
Q3
Q4
Q5
Q6

Pin
D
G
S
D
G
S
D
G
S
E
B
C
E
B
C
C

VDC
13.5
0.34
1.77
4.44
3.44
4.44
4.45
3.44
4.45
0.23
0.94
2.14
2.24
2.14
13.5
13.5

Ref.
Q7
Q8
Q9

Pin
B
C
B
C
E
B
C
E

E-6

VDC
0.7
*
4.39
5.61
3.74
0.3*
1.39
0*

Ref.

Pin

VDC

Ref.

Pin

VDC

Appendix F

Parts Placement Drawing (Top)(Includes KXPD1, KXB30, and KXAT1 boards)

6

K5

U2

D2

C42

C35

Q6

C34

C43

+

RP3

RP4

C51
Q1

1

DS1

CC

Q8

G

Q2
S

C13

C

U1

X1

- +

D1

C25

C5

FLAT
SIDE

R13

S1

C10

C33

C4
L8

C11
U5

602

S2 +

Q3

C2
D4

C55

G

KXPD1 REV B

KXPD1 REV B

2003
ELECRAFT2003
ELECRAFT

J4

R3

Q9
C8

U9
L9

C24

C18

S

L10

D

C32

1

C17 C19 C23

G D

B

D5

R12

4427

+

E

R19
(SOCKET)

R2 U3
C20

386

C1

U4

C16

C12

R1
L6

602

U8 S5

S4

CB

L7

RP5

RP1
S3

D2
D3

Z1

D6

C37

Q7

C47

C49
C48
C27

C52

U6

C38
U7

C44
C26

C54

C45

R31

RP2

+

C6

CA

C41

R11

C46

B
C
E

Q4
Q5

R9

C50

L2

L1

REV B1
2003 ELECRAFT

P2

C22

(SOCKET)

K4

Z2

L3

C11

C5

KX1

3

D1

U1

P3 C4

1

K6

K3

C6

4
2

K7

+

1

1
C7

P1

T1

K2
C8

RFC1 Z1

5

K1

D
5

C53

+

C
ELECRAFTKXB30
REV B1C21B

COPYRIGHT 2003

G
A

G

Appendix F Parts Placement Drawing (Bottom)(Includes KXPD1, KXB30, and KXAT1 boards)

C9

R4
R3

KXAT1 ATU REV B

C1
C2

FOOT

2003 ELECRAFT

NULL

C10

R2

C3

R1

REFL

3

+

R15

X2

C7
X3

C15

C
C3

30A

C9
C14

R18

R25

R16
X5

R5

G

X4

C1
C2

C5

D2
L3

L2
L1

C4

R5
R4

R17

R22
J3

C3

5
D

R29

R20

D1

J6

R23

P1+

G 30B

+

1

20B

G
R14

R10

R27

40

J1

R8
C39

R26

R28

A

L4

L5

20A

C31
C30

R6

1

R30

K1

R21

4

D7

L3

B
K2

2

1
J2

R7

R24

L1

J7 L2

J8

T1

R4

FWD

BAND/SPEED
Tap once to show
band, twice (quickly)
to change bands.
Hold to set keyer
speed with VFO knob

ELECRAFT KX1 QUICK REFERENCE
12V

S1 3

5

ANT.

7 9 +

RX
TX
RF 1

TUNE (key-down) :MENU

Hold MENU + BAND;
tap any switch after
power is displayed

2

RIT

0.5

2.0

2

SPEED

EDIT

Tap for 10/100 Hz,
hold for 1 kHz(5 kHz in LSB/USB
receive modes)

1.0

3

BAND

TUNING RATE:RF GAIN

1
CLR

TAP: 10 HZ / 100 HZ
HOLD: 1 kHz

LOCK/UNLOCK:FILTER

RIT + VFO knob

DISP

TUNE

DISP (display mode):
Hold BAND + RIT;
norm, Smtr, battery

VFO KNOBFUNCTIONSELECRAFT KX1

LAMP

POWER
ON

HIGH-PRIORITY MEM:KEY/
PADDLEOFF

BAND + VFO knob

AF GAIN

SWITCH CW:
RX MODE (sideband):
Hold MENU + RIT;
norm, LSB, USB

MENU/EDIT

RIT/CLR Tap for RIT on/off, hold for RIT clear

MENU + VFO knob

Tap to enter menu, hold to edit (except RCL and PLY); use VFO knob to scroll menu or modify parameters

LED

LED LEVEL (tap BAND or RIT);
LED TIMEOUT, use VFO knob

STLSIDETONE VOLUME LEVEL, 0-3

STP 

IAB

IAMBIC MODE, A or B

BAT

BATTERY WARNING THRESHOLDCFBAUDIBLE CW FEEDBACK,OFF or 10-40 WPM in 5 WPM steps

ATU

AUTO-TUNER MODE (see ATU manual)

RCLSIDETONE PITCH, 500-700 Hz

SLOS-METER ZERO SETMEMORY RECALL (tap 1, 2, or VFO);STORE (EDIT, tap 1, 2, or VFO;
hold rather than tap = high priority)

T-R

QSK DELAY, 0-900 ms

SHI

S-METER SCALE
PLY

RPT

AUTOREPEAT DELAY, 0-255 sec

B30 

30-M BAND on/off

MESSAGE PLAY (tap 1 or 2; tap VFO
knob for CW test mode, P=0);
RECORD (EDIT, tap 1 or 2)

INP

KEYING DEVICE: Hnd, PDn, PDr

CAL

VFO CALIBRATION (see manual)