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

ELECRAFT KX1

RF GAIN

BAND 1

RIT 2 CLR
DISP TAP: 10 HZ / 100 HZ HOLD: 1 kHz

FILTER

ON OFF

KEY / PADDLE

AF GAIN

O W N E RS M A N U A L

Ultra-Portable CW Transceiver

Owners 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

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 A SCHEMATIC...... APPENDIX B BLOCK DIAGRAM..... APPENDIX C PHOTOGRAPHS...... APPENDIX D TROUBLESHOOTING..... APPENDIX E PARTS PLACEMENT DRAWINGS..... APPENDIX F QUICK REFERENCE......APPENDIX G

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 KX1s controls are located on the top of 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 even standing. 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 digital synthesis) 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 KX1s 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 type used. The KX1 uses a 3-digit LED display that is physically rugged and extremely efficient. It requires just 1 to 2 milliamps total current in moderate 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 no surface 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. Wed like to thank you for choosing the KX1 transceiver, and hope it meets your expectations for ultra-lightweight portable operation. Wayne Burdick, N6KR Eric Swartz, WA6HHQ
Customer Service Information
Elecraft's 1-Year Limited Warranty

Technical Assistance

If you have difficulty with kit construction, operation, or troubleshooting, were here to help. You may be able to save time by first consulting our web site, www.elecraft.com, or by posting your question 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 to support@elecraft.com. Please use e-mail, rather than call, when possible since this gives us a written record of the details of your problem.

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

Assembly Notes

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

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 that provides just enough room for the case to fit together. Do not use sockets on any ICs other than the one provided. Mount the other ICs directly on the board as instructed. Sockets will not allow the cover to close. Also sockets in RF may cause improper circuit operation due to increased lead inductance and capacitance.
As you may have noticed already, the symbol below is used to alert you to important information:
Do not skip any steps. You may adversely affect both the performance 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 the case 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 in Appendix 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.

Assembly - Part I

In Part I, the control, display, and audio stages will be assembled and tested. Later sections cover receiver (Part II) and transmitter (Part III) assembly and test. If you havent done so already, open the bag of components labeled KX1 MAIN BAG and sort the parts into groups. Many of the components will be in small paper envelopes. Do not mingle the contents of one envelope with another. As you are instructed to locate particular components, use the photographs in the KX1 PCB parts list in Appendix A to help identify them.

BEFORE YOU START:

1. WEAR A GROUNDED WRIST STRAP or ground yourself briefly before touching components. You can discharge static by frequently touching an unpainted, grounded metal surface. 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.

The components pre-installed on the circuit board are extremely static-sensitive. Wear a wrist strap or ground yourself before handling the board. 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 for resistor R8 next to the outline for J1.
Bend the leads of resistor R8, 6.8k (blu-gry-red), 1/4 watt, at right 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 the board 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 be bent 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. Solder the leads to R28 and trim them flush with the board.
Components MUST be tight against the board or the case may not close properly during final assembly. This is especially true of components on the bottom of the board where there is very little clearance between the board and the battery packs.
Check the position of the resistor to ensure it is centered in the printed outline and flush against the board as shown in Figure 3. Solder and trim the leads.
ENSURE MARKINGS AGREE WITH INSTRUCTIONS IN TEXT BODY OF PART AGAINST THE BOARD
From this point forward, instructions to install a component 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 just installed. Install the 1/8 watt resistors in the spaces shown just to the left of R8 near the top of the board:

The Tap/Hold Rule

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 shows the HOLD function (yellow lettering). To highlight this in the text, we use two different typographical styles to identify switches: T AP and HOLD.
Frequency Display and Band Change
The display shows three digits of the operating frequency. Which three digits are shown depends on which tuning rate youve selected: 1 kHz, 100 Hz (default), or 10 Hz. At 7100.00 kHz, the three tuning rates produce the following displays:

7100.00

Accessing the Configuration Menu
Tap M E N U to enter the KX1s 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. Use the knob to return to the LED menu entry. Then hold E D I T to change the LED parameter. The display will change to L followed by a number from 0 to 6. 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 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 the knob, 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.) Tap M E N U once to return to menu scroll mode, then tap it again to return to the frequency display.
To select 1 kHz steps, press and hold the VFO knob (from now on, well 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 The tuning rate alternates between 10 and 100 Hz steps as you tap, and the decimal point moves accordingly.

/ 0 H z ).

You can check the MHz and kHz digits at any time by tapping. For example, if the VFO frequency is 7100.00 kHz, tapping will first show 7 , then 100, then return to the appropriate display for your selected tuning rate.

B AN D B AN D

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.) Set the POWER switch to OFF. Disconnect the power source from J1. Remove the VFO knob and set it aside for reinstallation later. Wrap the cover and put it in a safe place until it is needed. Leave microcontroller U1 in its socket during the remainder of the assembly process. Be sure to observe ESD handling precautions at all times.

Turn the board top face up with KX1 in the upper left corner. Install potentiometer R2 (B10K) as follows: _ 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 to make 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 good electrical and mechanical joint between the tab and the plated hole. Do NOT try to fill the hole with solder.
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.
Install potentiometers R1 and R3 following the same procedure. _ _ R1 (B1K) above R2. R3 (B1K) below R2.
Separate the three potentiometers according to their values: _ _ Two 1k pots (B1K) One 10 k pot (B10K)
In the following steps youll 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 cores and two dark gray FT37-43 cores. Use the yellow cores to make L1 and L2. Although the yellow and gray cores look similar, they have very different electrical properties. You must use the yellow cores for 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: _ _ 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 the core. There are no half or quarter turns when winding a toroid. Match the winding direction shown in the figure or the leads wont line up with the solder pads on the circuit board. Spread the turns around the core so the finished result looks like Figure 16.

BOTTOM OF BOARD

Figure 17. Trimmer Adjustments.
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 fixed capacitor.
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.
Locate a small flat-blade screwdriver or tuning tool for use in adjusting 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 hand capacitance from affecting the adjustment.
The trimmer access holes on the revision B and B1 KX1 PC boards are plated through and grounded. This may make alignment more difficult if youre using a tool with a long metal shaft, rather than a tuning tool with just a metal tip. This is not a safety hazard, but you may need to remove the tool after each adjustment 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, peak trimmer capacitors 20A and 20B. If the peak is not clear, reduce the signal input level (the AGC may be getting activated). Do not turn the RF GAIN control counter-clockwise, as this will broaden the tuning peaks, making them more difficult to identify.

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. Youll see a brief bar-graph test pattern, then the display 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 the signal is tuned in, the AGC should be activated, as indicated by an increase in S-meter reading.5 The S-meter zero point and scale can be adjusted, if necessary, using the SIG menu entry (page 65).
If you dont hear band noise or signals, be sure you installed the jumper across the outer pins of J7 as described on page 41. Tap B AN D twice (quickly) to select the 7 MHz band. Set the VFO to about 7100 kHz.
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 the limiting action of U4 (AF amp), since U4 is operated from a low voltage. (See schematic, Appendix B.)
Each bar corresponds to roughly two S-units, so that 4 or 5 bars indicates about an "S-9" signal.
Receive Current Drain Test (Optional)

_ _ _ _

Install toroidal inductor L3 and solder both leads. Check for continuity (less than 1 ohm) between the solder pads. Do NOT attach L3 or T1 to the circuit board with adhesive or other compounds. They should be supported only by their leads. 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 the short standoff. One pair of standoffs installs near J8 and K2 (on the bottom face of the board) and the other pair installs in the hole near P1 and J6.
TOP FACE OF BOARD 5/16 STANDOFF
Place the front panel (top cover) face down on a soft cloth to avoid scratching it. Remove the paint from around the screw holes where the short standoffs will contact the front panel as shown in Figure 21. Use sandpaper or a sharp knife. Clean the panel thoroughly to remove all of the residue when you are done. Inspect the area where the thermal pad will mount and be certain there are no burrs that could poke through the thermal pad. Burrs are most likely to be found around the hole. Sand file any rough edges smooth.

NO WASHER HERE!

SPLIT WASHER

3/4 STANDOFF

Figure 20. Installing Standoffs on Circuit Board.
Figure 21. Preparing Top Cover for Installation.
Position the red filter over the LED display opening. Use the clear 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.
Locate the thermal pad. Leave it on the backing paper while you remove the piece filling the hole near one end. Then remove the backing 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 (see Figure 22).
Figure 23. Installing Display Filter. Figure 22. Installing Thermal Pad.
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 Q6s leads into a gentle 90-degree curve (see Figure 24). Note that the flat side of the transistor faces away from the circuit board. Wrapping the leads around a round screwdriver shaft or drill bit helps avoid sharp kinks in the bend.

53 Locate the silk-screened outline for Q6 at the top edge of the circuit 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 reach the 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 Q6s leads in the holes in the circuit board. Do not solder them until instructed to do so.
Figure 24. Installing Power Amplifier Q6.
54 Temporarily secure Q6 to the standoff with a 4-40 flat head screw. Tighten the screw enough to hold Q6 securely and parallel to the circuit board. Use your long-nose pliers to adjust the leads so the flat side of the transistor 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 heat efficiently. Solder the three leads to Q6. Trim them flush on the bottom side of 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 a magnifier. Check especially for the following: _ _ _ 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 KXBmeter or KXBmeter band module. These pads are labeled A, B, C, D, 5 and three pads labeled G.
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 dont line up properly with the holes in the cover, use a long tool to reach between the cover and the circuit board to nudge the caps into the holes. _ Finally, you will need to push down gently on the key jack to make 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-head screws. Do not over-tighten any of these screws.

If you installed a 2SC2166 (metal tab) transistor at Q6, NEVER install a metal screw in the tab of Q6 when the unit is out of 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 to ground when power is applied. This may cause serious damage to the circuit board or other components.
Turn the unit face down on a soft surface and measure the resistance 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 tab on the transistor is touching the case instead of the thermal pad. Install the knob on the encoder shaft.
55 Find the battery holders and inspect the bottom of one. Note the ridges 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 and under the holders as shown to avoid interfering with other components when the KX1 case is closed.
ROUTE BLACK WIRES UNDER BATTERY HOLDER AND AROUND SCREW. BE SURE WIRES LIE FLAT AND DO NOT CROSS OVER EACH OTHER. RED 2-3/4 (7 CM) BLACK CUT TO MATCH LENGTH OF RED REMOVE PAINT FROM AROUND HOLE ON INSIDE OF COVER
REMOVE PAINT FROM AROUND HOLE ON INSIDE OF COVER ROUTE RED WIRE UNDER BATTERY HOLDER AND AROUND CORNER NUB BLACK 4 (10.2 CM)

RED 3-1/4 (8.3 CM)

SPLICE MUST LIE FLAT ON BOTTOM. KEY JACK J3 AND CRYSTALS ON THE BOTTOM OF THE CIRCUIT BOARD FIT IN THIS AREA.
TUCK EXCESS RED WIRE UNDER BATTERY HOLDER.
Figure 25. Wiring the Battery Holders.
Slip the three wires shown in Figure 25 under the edge of the holder as follows: _ _ Position the red wire so it goes under the holder and around the 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.
Begin by removing the paint from around the holes on the inside of the bottom cover where it will attach to the stand-offs on the circuit board. 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 the black wire its full, original length. Repeated insertion and removal of the 2-56 screws used in the following steps may result in stripping the threads in the bottom 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, youll need to replace the supplied screws with longer screws, along with 2-56 hex nuts. 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 this may strip the threads. Be sure the wires exit at the left end as shown. 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.

Figure 28. Installing Serial Number Label. Figure 27. Installing Feet.
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 the area shown below (See Figure 29 ). Fold down or re-solder components if necessary. Also trim any long component leads which were not trimmed earlier.
When 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 have a 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).
Figure 29. Checking Component Clearance.
If you have purchased KX1 internal options, do not install them until becoming familiar with basic KX1 operation. Options can be installed in any order. (All KX1 options are described on page 71.)
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.

Operation

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

External Power Supply

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 will be 300-700 mA, depending on the supply voltage.

Connections

Internal Battery
Connect the internal battery to P1 on the PC board. Make sure the battery wires arent pinched when you install the bottom cover. Battery Selection: For best performance, use 1.5-volt cells (9 volts see table). Energizer lithium type L91 or fresh Alkaline cells are recommended. Lithium cells are more expensive, but have high energy density, a flat discharge curve, and weigh less than Alkalines. 1.2-volt cells (e.g. NiMH) can also be used, but will provide lower output and reduced operating time, and near end of charge will not meet the KX1s minimum supply voltage spec (7 V). You must remove rechargeable batteries (e.g., NiMH) for charging. Battery Type 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.

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 and 80m 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 front of 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.

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 digital synthesis) 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 portable station 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 order to 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-m band edge. Because of this, LSB receive mode on 20 meters is less sensitive; 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 form a 3-stage buffer for the DDS signal. Maximum power output from the final 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 can reach the receive mixer when the rig is in transmit mode. Microcontroller: A low-power microcontroller (U1, MCU) is used to control the transceiver and handle user interface elements, such as the display 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).

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 youll 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 Receiver Transmitter and Keyer 00-19 20-39 40-59 60-79 80-99
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.
General Troubleshooting (00-19)
General Troubleshooting Procedure
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 by pressing any switch. However, the cause of the message should be investigated before continuing to operate the transceiver.
Problem 00 Unit appears to be completely dead when power switch is turned on (no display, no audio); possible smoke, hot components, etc.
01 LED problem 02 BAT LO displayed
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 is excessive 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 was just initialized 15 END or P=0 is displayed on keydown
See Receiver troubleshooting table (60) Check regulated voltages (20); look for a component thats 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)
24 LED display problem 25 Relay Problem 26 Possible MCU problem

BY DAVE INGRAM,* K4TWJ
CQ Reviews: Elecrafts New KX1 CW Transceiver Kit
o doubt about it, friends, QRP is the hottest special interest in amateur radio today! Just step back and look at the escalating worldwide interest in low-power communications, the numerous on-theair QRP contests, QSO parties, and all the dazzling QRP gear, and you, too, will agree. It is maximum enjoyment at minimum cost. You can go first class with a brand-new attentiongrabbing QRP transceiver plus antenna and accessories and still have money left over for other pursuits. Now that feat is hard to beat in todays world! Ready to add an exciting new dimension with real go-anywhere, do-anything flexibility to your amateur radio life? Get rolling with QRP and start enjoying the good life! As further encouragement to do more with less, this months column Photo 1 Equipped with all its options, Elecrafts new KX1 is a takes an up-close look at Elecrafts three-band CW transceiver with built-in battery pack, automatic captivating new KX1 transceiver kit. antenna tuner, electronic keyer and paddle, LED, plus Morse code This multi-feature and coat-pocket- readouts and even a logging light. The little rig is microprocessor size rig is quite reasonably priced, a controlled with a superb receiver, 4-watt transmitter, and silky smooth break-in operation. (Photo courtesy Elecraft) great little performer, and also surprisingly easy to assemble, even if you only have a few minutes of spare time a day. lines). Current drain is very trail-friendly at 32 ma I did it, and my spare time is tighter than my month- receive and less than 700 ma on transmit at full ly budget! I also took the new KX1 on a QRP road power and about half that current at 2 watts, so trip you should find interesting, so read on as we battery life is exceptionally good. An optional CW paddle and internally mounted automatic antenna discuss Elecrafts new kit. tuner further enhance stand-alone operations with the KX1. The tuner is a gem. It matches coax-fed The New KX1 antennas such as dipoles and verticals, and it also Wayne Burdick, N6KR, and Eric Swartz, works with random longwires (reallylongwires). WA6HHQ, of Elecraft have done it again. They It uses latching relays to hold settings without have developed and packaged another outstandkeep alive current. The optional paddle, which ing CW transceiver kit, and it is loaded for big-time can be attached quickly, makes the KX1 a comradio action! The new KX1 sports top-mounted plete grab and go station you can carry anywhere controls for easy campsite, laptop, or handheld in a coat pocket. Now this is QRP in style! use. It is quite small (the size of a QSL card and The KX1 really shines in the special-features only 1.2 inches thick) and fully self-contained. The department. It has a direct digital synthesized little transceiver covers 40 and 20 meters plus (DDS) VFO with microprocessor control, LED receives adjacent-to-band frequency ranges and readout, three tuning rates, RIT, three-pole crystunes the 49- and 22-meter international shorttal filter, three frequency memories per band, and wave broadcast bands. An optional module adds built-in electronic keyer with two message memo30-meter operation and enhances reception from ries plus a beacon or auto-CQ mode. Receive 8 to 12 MHz. Power output is approximately 4 watts bandwidth is panel-adjustable from approximateof band-blasting RF with a 13.5-volt DC supply or ly 2.0 kHz to a hair-splitting 300 Hz, and CW T/R 2 watts when using internal batteries (six AA alkadelay time is selectable from 900 ms right down to zero. I think there is also a rocket launcher in there; I just have not found it yet. *4941 Scenic View Drive, Birmingham, AL 35210 Particularly attractive is the KX1s on-board e-mail: <k4twj@cq-amateur-radio.com> microprocessor with a 16-function menu set that
lets you customize the KX1 to fit your personal preferences. As an example, you can set the LED readout to bright or dim or to switch off after a selected time. You can also set the sidetone level and pitch, T/R delay, CW message record and play, beacon repeat internal, and low-battery-level warning point, plus switch the auto antenna tuner and Morse readout announcer on/off via the menu. If that is not enough, the microprocessor also has a second 100-count troubleshooting menu set that reads out a code when there is a problem, and the KX1s manual explains how to read the code and find the problem.

Building the KX1

It is difficult to believe this is a kit transceiver (it is elaborate!) or that it is easy to build, but both the rig and its manual are so well planned and laid out that anyone who can follow hand-holding, step-by-step instructions can do it. At the chance of sounding dumb, I would say if you have the time and patience to put together a couple of jigsaw puzzles, even if it is only a few pieces a day, you can build a KX1. All the components even the controls, connectors, and readoutjust mount in clearly marked holes on the main PC board. There are no wires to run, cross, or get confused. You cant miss. Dislike winding toroids? No problem. Check with Mychael Morohovich, AA3WF, at 412-481-2349 or e-mail him at <toroidguy@ earthlink.net>. Mychael winds and sells toroid sets for the KX1, K1, and K2, and I can say firsthand that they are well worth the cost! I would estimate total KX1 assembly time as around 20 hours, and you gain substantial hands on experience working with new millennium circuitry in the process. While on a special-frills roll, incidentally, check out the stick-on tuning-knob spinners from Wayne Smith at <K8FF@ fingerdimple.com>. (See photos for more on constructing the kit.) Circuit-wise, the KX1s single-conversion receiver consists of an NE612 front end mixer, a crystal filter, another NE612 as a BFO and product detector, and an LM-386N audio amplifier. Dual JFETs are included for receiver muting, and a transistor circuit handles AGC. The transmitter consists of three transistor stages driving a hefty 2SC2166 to 4 watts output. As previously mentioned, a microprocessorcontrolled DDS VFO drives both receive and transmitter sections. The KX1s manual is such a great tool for teaching new and seasoned amateurs alike how
Photo 2 The full Elecraft KX1 kit as received, unpacked, and ready for assembly. Various components such as resistors, capacitors, and inductors are packaged in separate envelopes, while larger items such as transistors and ICs are in static-safe bags. The optional 30-meter board, antenna tuner, and paddle are also in separate bags.
Photo 3 Assembly begins as various parts, switches, and LED display begin filling holes on the main PC board. The keys to building a kit rig such as the KX1 are a steady hand, small soldering iron, thin solder, patience, and a good magnifying visor (I use an inexpensive one from Nancys Notions, 1-800-833-0690).
Photo 4 This reverse view shows how small parts mount on both sides of the main PC board. The receiver has now been assembled, and the transmitter section is half completed. Assembly has also begun on the optional automatic antenna tuner (long, narrow board) and 30-meter mod (small board). Two pre-wound toroids from AA3WF have been installed, two are ready to be installed, and four for the tuner are in envelopes. to work with modern micro parts and PC boards that, thanks to Elecraft, it is the highlight of next months How It Works column. Watch for it! My KX1 worked like a champ right from turn-on. Even before I could check out and tweak the receiver on 30-meter band noise, I heard a YV calling CQ. I called him and received an immediate reply. I was still dinking with keyer speed settings and connecting a wattmeter to measure output when a KL7 started QRZing me, so I worked him, too (tweaking? Who needs it?!). I then

switched to 20 meters and, by Jove, there was a YU completing a CQ. Yep, I worked him too. The little KX1 is a killer! After the fun and games calmed down slightly (new rigs are so exciting!), I discovered several cool treats not mentioned in magazine ads. High-speed diodes are used for T/R switching, for example, so the previously mentioned T/R delay only affects receiver mute time. I also noticed the extended receive coverage was perfect for checking signal propagation reports from WWV on 10.0 MHz at 18 minutes after each hour and for monitoring east coast aviation weather data from New York Central on 10.051 MHz. Another neat surprise was the Morse Frequency Readout. You just tap the Band button once to read the frequency in Morse code and tap it again to switch bands (and read the new frequency). If you depress the Band button for one second, the keyers speed is read in Morse, and speed changes (made by the main tuning knob) then also read in Morse. Tap the RIT button and you hear R and O for on and off. Tap the Menu button, scroll with the main tuning knob, and all menu selections read out on the LED and also in Morse. Those of us with visual impairments will find this feature essential. We could continue for several more pages, but describing all of the KX1s assets in this columns limited space is nigh impossible. We thus encourage you to check with Elecraft at 831-6628345 or <www.elecraft.com> for more
Photo 5 Top view of the fully assembled KX1 ready for installation in the case. The LED display is in middle left, the main tuning encoder (dial) is in middle right, and the three controls are vertical on the right. The RF output transistor is above the tuning encoder, the 30-meter board is mounted upside down below the encoder, and the automatic antenna tuner is mounted on the back side of the main board. The kit goes together very well.
Photo 6 Our minimalist gear laid out for the QRP road trip. Items include the Elecraft KX1 with optional case-mount paddle, external Parkwood paddle from WB9LPU (wb9lpu@earthlink.net), MFJ AC power supply, Maldol pullup antenna with clip-on counterpoise, and self-supporting Buddipole antenna. Mobile antennas are not shown.
Photo 7 The main key to successful QRP mobiling is using the vehicles metal frame as a solid ground. Here we scraped off 1/4 inch of paint so one of the mounts screws connects to ground. We then added a base matching coil and connected its ground strap to the mounts screws. A VOM check confirmed solid grounding.
Photo 9 Poolside portable setup. Just plop down the rig, stretch out the counterpoise strap, and you are on the air in less than a minute. Try that with a big 100-watt rig. By the time you set up a power supply and run an antenna cable, I will have worked all the DX and gone parasailing! alike, the secondary purpose of our short road trip was to check out the retirement possibilities and medical facilities in Panama City, Florida and Dothan, Alabama. Since we were traveling in a rental car, staying in motels, and moving at warp speed, hamming on the fly with minimum time for rig setup was vital. Typical of unexpected circumstances, we were never in one spot long enough to string up a wire antenna or even quickly assemble the multiband Buddipole antenna we carried for use on the beach. Our main on-the-air time was mobiling from the car with the KX1 and 7-foot Hamsticks and operating poolside portable with the KX1 and a Maldol pull-up antenna (handicaps some non-QRPers would consider overwhelming). The results? While sporadically operating 20 meters during daylight hours, I worked stations from coast to coast with an approximate 75-percent reply to all callseven to our own CQs. Results on 30 meters at night were even better, with 85percent return to calls, many including good DX QSOs. Judging from past experiences under similar circumstances, I doubt that I would have been any more if I had used a 50or 100-watt rig. The only good one that slipped away was a VK at daybreak on 30 meters. We were traveling in a fog and had to stop for food and fuel before I could call him. The fate of that call will always be a mystery, but one fact is certain: A little QRP goes a long way! On that cheerful note, we must once again sign off for another month. Keep on working the world with low power, and I will be listening for you week nights on 30 meters. 73, Dave, K4TWJ

Photo 8 Instant mobiling in a rental car is easy. Just put the transceiver in your lap, let the XYL drive, and use a small earbud for good copy over road noise and screeching tires. Notice the separate ground strap clipped to the antenna plug; it routes directly to a body bolt under the seat and makes a big difference in performance.
details or to purchase your own KX1. There is no better way to really get into QRP than with a brand-new dedicated QRP rig. Go for it!

QRP Road Trip

After getting going with the KX1, and with some folks still questioning if QRP really works out under totally unpredictable circumstances, we recently put our low-power show to the test. The results were most interesting. In addition to proving QRPs worth during good and adverse conditions
(Reprinted with permission from CQ Communications, Inc., February 2004 issue of CQ)