Pozosta ELECRAFT-KPA100 User Manual

Download

Page 1

Downloaded by

RadioAmateur.EU

Appendix G, 100-W Stage and RS-232 I/O (K2/100)

Rev A, May 13, 2002

Page 2

Table of Contents

Introduction................................................................................................................................................................................................................3

Preparation for Assembly.................................................................................................................................................................................................3

Tools Required..............................................................................................................................................................................................................3

Pre-Wound Toroids........................................................................................................................................................................................................3

Parts Inventory...........................................................................................................................................................................................................3

Assembly, Part I......................................................................................................................................................................................................11

Initial Tests...............................................................................................................................................................................................................20

Assembly, Part II.....................................................................................................................................................................................................24

Alignment and Installation....................................................................................................................................................................................41

Receiver Tests.............................................................................................................................................................................................................44

SWR Bridge Null Adjustment (C1).................................................................................................................................................................................44

Power Calibration (R26 and R27)...................................................................................................................................................................................45

Temperature Calibration (CAL tPA)................................................................................................................................................................................45

KPA100 Power Supply Test..........................................................................................................................................................................................45

Fan Test.....................................................................................................................................................................................................................46

External Amplifier Keying Test (PA KEY).......................................................................................................................................................................46

Bias Current Adjustment...............................................................................................................................................................................................46

Transmit Tests.............................................................................................................................................................................................................47

Installation..................................................................................................................................................................................................................48

Using the K2/100 at High Power.........................................................................................................................................................................49

Power Supply..............................................................................................................................................................................................................49

Antenna......................................................................................................................................................................................................................49

Controls.....................................................................................................................................................................................................................50

Remote Control using the RS232 Port...............................................................................................................................................................51

Control Board Preparation.............................................................................................................................................................................................51

RS-232 Interface Setup and Test.....................................................................................................................................................................................52

Computer Control........................................................................................................................................................................................................53

K2/100 Specifications............................................................................................................................................................................................56

Troubleshooting and Repair................................................................................................................................................................................57

Circuit Details..........................................................................................................................................................................................................60

KPA100 Schematic.................................................................................................................................................................................................61

Parts Placement Drawing.....................................................................................................................................................................................63

Page 3

Introduction

Pre-Wound Toroids

Appendix G describes assembly of the K2/100 transceiver's internal 100-watt final output stage (KPA100 board). The PC board includes two conservatively-rated RF power transistors, low-pass filters, SWR bridge, monitoring circuits, speaker, and an RS232 interface. Filter switching, T-R sequencing, and other configuration is handled by the K2/100's main microcontroller.

KPA100 assembly and installation should be done only after the transceiver has been aligned and tested at the 10-watt level.

Preparation for Assembly

With all equipment that operates at high power levels, proper assembly and alignment are critical for safe and reliable operation. Follow the instructions carefully and make all of the recommended measurements. Do not substitute components or perform any assembly steps out of order.

Please read the following information regarding tools and toroids before proceeding.

Tools Required

The following tools are required to build this kit:

• Flush-cutters (Hakko CHP-170, Xcelite 170, etc.). Ordinary

diagonal cutters are not suitable for flush-cutting (trimming leads very close to the board).

• Temperature-controlled soldering station with a fine-point,

800-degree (F) tip. Do not use a high-wattage iron or gun with

small components, since this can damage pads, traces, or the parts themselves.

• Larger iron or soldering gun. This will be used only for

installation of power transistors, output transformer, and DC power wiring. A low-wattage iron cannot be used for these steps.

• Digital Multimeter (DMM). A DMM with capacitance

measurement capability is desirable, though not required.

Refer to our web site for tool sources and solder recommendations.

The toroids on the KPA100 board are not difficult to wind, and detailed instructions are provided (beginning on page 24). All toroids

must be wound and prepared correctly, or the power transistors may be damaged.

If you prefer not to wind the toroids yourself, you can obtain a full set of pre-wound toroids (with leads stripped and tinned) from an Elecraftqualified source. A toroid order form may have been supplied with your kit. You can also find ordering information at www.elecraft.com. You

do not need to send your cores or wire to the winding service.

Parts Inventory

Set the heat sink and painted panels aside until needed. Leave

them wrapped to protect their finish.

You should do a complete inventory (parts list starts on page 4), which will take 2 to 3 hours. If anything is missing, contact Elecraft. Color codes and other markings are shown in parentheses. Refer to Appendix A of the owner's manual for additional parts photos.

Some components in this kit can be damaged by static discharge. Before handling diodes, transistors, and ICs, touch a grounded, unpainted metal surface, or use a wrist strap.

Parts List Notes:

• LS = lead spacing (0.1" = 2.5 mm, 0.2" = 5 mm, 0.4" = 10 mm.)

• In some cases, two capacitor types will have the same value

but different voltage ratings or lead spacing (LS). To avoid assembly errors, you must positively identify these capacitors and keep them separate from each other. Use your DMM to verify values if possible.

• Parts shown in bold are for use on the K2 RF or Control boards.

• Flat-head screws are measured from the top of the head; pan head

screws are measured from beneath the head.

Page 4

Picture Ref. Designator(s) QTY Description Part #

C5B 1 Cap., 18 pF ("18"), 5%, 500V or 1KV disc, 0.2" LS (may have black band) E530088 C3B,C4B 2 Cap., 27 pF ("27"), 5%, 500V or 1KV disc, 0.2" LS E530089 C5F 1 Cap., 33 pF ("33"), 5%, 500V or 1KV disc, 0.2" LS E530090 C3H 1 Cap., 39 pF ("39"), 5%, 500V or 1KV disc, 0.2" LS E530091 C5D 1 Cap., 47 pF ("47"), 5%, 500V or 1KV disc, 0.2" LS E530092 C4D 1 Cap., 56 pF ("56"), 5%, 500V or 1KV disc, 0.2" LS (may have black band) E530093 C5A,C6C 2 Cap., 68 pF ("68"), 5%, 500V or 1KV disc, 0.2" LS E530094 C3E,C5G 2 Cap., 82 pF ("82"), 5%, 500V or 1KV disc, 0.2" LS E530095 C4E 1 Cap., 120 pF ("121"), 5%, 500V or 1KV disc, 0.2" LS E530096 C3G,C4A,C5C,C5E,

C6E C2B,C3C,C3J 3 Cap., 220 pF ("221"), 5%, 500V or 1KV disc, 0.2" LS E530098 C3A,C3D,C4C,C6F 4 Cap., 270 pF ("271"), 5%, 500V or 1KV disc, 0.2" LS E530099 C3F,C6A,C6B,C6G 4 Cap., 330 pF ("331"), 5%, 500V or 1KV disc, 0.2" LS E530100 C2D 1 Cap., 390 pF ("391"), 5%, 500V or 1KV disc, 0.2" LS E530101 C26 1 Cap., 33 pF ("33"), 5%, 50V disc, 0.2" LS (do not confuse with C5F) E530064 C41,C95 2 Cap., 100 pF ("101"), 5%, 200V disc, 0.2" LS E530034 C66 1 Cap., 180 pF ("181"), 5%, 50V disc, 0.2" LS; voltage may not be marked E530008 C80,C81 2 Cap., 4700 pF ("472"), 10%, 100V disc, 0.25" LS E530102 C2E,C83 alternate 2 Cap., 1000 pF ("1000"), 5%, 500V silver mica E530085 C2A,C6D,C83 3 Cap., 1200 pF ("1200"), 5%, 500V silver mica E530033 C2C 1 Cap., 2200 pF ("2200"), 5%, 500V silver mica E530086 C84 1 Cap., .001 µF ("102"), 5%, 50V mono, 0.1" LS E530074 C25,C69,C70,C87,

C88, CTRL-Ctxd C82 1 Cap., 1200 pF ("122"), 5%, 50V mono 0.2" LS E530005 C71 1 Cap., .0018 µF ("182"), 5%, 200V mono, 0.2" LS E530104 C64 1 Cap., .0018 µF ("182"), 5%, 630V mono, 0.4" LS E530105 C7,C8,C9,C12–C22,

C24,C28,C29,C32, C50,C65,C72,C73, C74,C76,C97–C99

C37,C38,C39,C44, C46,C68,C89,C90

C36,C42,C43,C77 4 Cap., .015 µF ("153" or "15N"), 5%, 250V mono, 0.2" LS E530082 C31,C67 2 Cap., .033 µF ("333" or "33N"), 5%, 250V mono, 0.2" LS E530083 C79 1 Cap., .039 µF ("393"), 5%, 200V mono, 0.4" LS E530103

5 Cap., 150 pF ("151"), 5%, 500V or 1KV disc, 0.2" LS E530097

6 Cap., .001 µF ("102"), 5%, 50V mono, 0.2" LS

(CTRL-Ctxd may be needed for K2 Control board; see text)

27 Cap., .01 µF ("103"), 5%, 50V mono, 0.1" LS E530019

8 Cap., .01 µF ("103"), 5%, 50V mono, 0.2" LS E530009

E530001

Page 5

Picture Ref. Designator(s) QTY Description Part #

C48,C49,C52–C57, C61-C63,C85,C86.

RF-Crf

C30,C33,C34,C75 4 Cap., 0.1 µF ("104"), 20%, 50V mono, 0.1" LS E530020 C10,C11,C23,C35,

C58,C59,C40,

CTRL-C42

C1,C27 2 Cap., 5-30 pF ceramic trimmer E540001 C60 1 Cap., 100 µF, 16V electrolytic E530061 C51 1 Cap., 470 µF, 25V electrolytic E530084 D1-D8 8 Diode, 1N4148 E560002 D9 1 Diode, SB530 E560003 D10,D13 2 Diode, 1N5404 E560010 D11,D12,D14 3 Diode, 1N4007 E560001 D16,D17 2 Diode, 1N5711 E560004 E1 1 Ground terminal, right angle PCB mount, 6-32 threaded E700012 FAN1 1 Fan, 12 V E980046 J2 1 Connector, SO239 (Antenna) E620064

Cap., .047 µF ("473"), 5%, 50V mono, 0.2" LS

(RF-Crf may be needed for the K2 RF board; see text)

8 Cap., 0.1 µF ("104"), 5%, 50V mono, 0.2" LS

(CTRL-C42 may be needed for the K2 Control board; see text)

E530025

E530011

J3, P3 2 Connector, DC power, red housing (13.8 VDC input and mating conn., +) E620059

J3, P3 2 Connector, DC power, black housing (13.8 VDC input and mating conn., -) E620060

MISC 2 PCB pin for J3, 25 amp right angle E620061

MISC 2 Crimp/solder terminal for P3, 30 amps E620062

Page 6

Picture Ref. Designator(s) QTY Description Part #

HDWR 2 Mounting plate for J3 E620063

MISC 1 Spring pin, 3/32" x 1/4" (2.4 x 6.4 mm); stabilizing pin for P3 E700071

J1,J4 2 Connector, 2p female housing, 0.156" spacing (12V and RF connectors) E620013 RF-P3, RF-P6 2 Mating connectors for J1 and J4, 2p male, 0.156" spacing (K2 RF board) E620012 HDWR 5 Crimp/solder terminal for J1 and J4, gold color (1 spare) E620014 J5 1 Connector, 2p female housing, 0.1" spacing (AF In) E620021 HDWR 3 Crimp/solder terminal for J5 (1 spare) E620022 J6 1 Connector, 1/8" mono jack w/switch, PCB mount (ext. speaker) E620056 J7 1 Connector, RCA jack, PCB mount (ext. PA key) E620057 J8 1 Connector, DB9F, PCB mount (RS232 interface) E620058 MISC 2 Keying insert for ribbon cable connector

(Shown approx. 4x actual size; may include large break-away tab)

MISC 1 Connector, DB9M (serial I/O cable, K2 end) E620049 MISC 1 Connector, DB9F (serial I/O cable, PC end) E620048 MISC 2 Backshell for serial I/O cable E620050 K1-K12 12 Relay, SPDT, 12 V E640011 L1,L2,L13,L14 4 Toroidal inductor, T50-2 core (iron powder, red, 0.5" dia.) E680005 L4-L8,L10-L12 8 Toroidal inductor, T50-10 core (iron powder, black, 0.5" dia.)

E700065

E680016

Note: One gray ferrite core of the same size is also supplied (see T4). The T50-10 iron power cores have a shiny, black finish, while the

ferrite core is dull gray in color. Keep the two types separated. L15,L16,L18 3 Toroidal inductor, T44-2 core (iron powder, red, 0.44" dia.) E680012 P1 1 Connector, 10 pin dual row (5 x 2), 0.1" spacing E620040 Q1,Q2 1 Matched set of (2) 2SC2879 transistors E850123 Q3,Q4 2 Transistor, NPN, MJE182, TO-225AA package E580016 Q5,Q8 2 Transistor, NPN, 2N3904, TO-92 E580017 Q6,Q7 2 Transistor, MOSFET, 200 V, ZVN4424, TO-92 E580005 Q10,Q11,Q12 3 Transistor, MOSFET, 60 V, 2N7000, TO-92 E580002 Q9 1 Transistor, HEXFET, 500 V, IRF830 or IRL620, TO-220 (tab may be cut) E580018 R2,R3 2 Resistor, 2.7 ohms, 5%, 1/4 W (RED-VIO-GOLD) E500055 R9 1 Resistor, 10 ohms, 5%, 1/4 W (BRN-BLK-BLK) E500054

Page 7

Picture Ref. Designator(s) QTY Description Part #

R10 1 Resistor, 47, 5%, 1/4 W (YEL-VIO-BLK) E500019 R1,R29,R15,R16 4 Resistor, 3.3 k, 5%, 1/4 W (ORG-ORG-RED) E500017 R8 1 Resistor, 10 k, 5%, 1/4 W (BRN-BLK-ORG) E500015 R5 1 Resistor, 15 k, 5%, 1/4 W (BRN-GRN-ORG) E500060 R4 1 Resistor, 100 k, 5%, 1/4W (BRN-BLK-YEL) E500006 R12 1 Resistor, 180 k, 5%, 1/4W (BRN-GRY-YEL) E500068 R11 1 Resistor, 510 k, 5%, 1/4W (GRN-BRN-YEL) E500069 R32 1 Resistor, 100 ohms, 1%, 1/4W (BRN-BLK-BLK-BLK)

Note: This resistor looks very similar to the small 100-µH RF choke (RFC3, etc.). RF chokes can be identified by their much lower resistance,

if necessary (typically 1 to 8 ohms). R30 1 Resistor, 3.09 k, 1%, 1/4W (ORG-BLK-WHT-BRN) E500072 R24,R25 2 Resistor, 8.45 k, 1%, 1/4W (GRY-YEL-GRN-BRN) E500071 R28,R31 2 Resistor, 200 ohms, 5%, 1W (RED-BLK-BRN) E500074 R23 1 Resistor, 10 ohms, 5%, 1 W (BRN-BLK-BLK) E500083 R14 1 Resistor, 470 ohms, 5%, 1W (YEL-VIO-BRN) E500075 R19,R20 2 Resistor, 3.6 ohms, 5%, 2W E500084 R21,R34,R35 3 Resistor, 10 ohms, 5%, 2W (do not confuse with R23) E500077 R38,R39 2 Resistor, 68 ohms, 5%, 2W E500078 R13,R22 2 Resistor, 100 ohms, 5%, 3W E500080 R7 1 Resistor, .005 ohms, 1%, 3W (current sensing) E500079 R6 1 Potentiometer, 1K trimmer ("102"), bias set E520010 R26,R27 2 Potentiometer, 100K trimmer ("104"), SWR set E520001 RFC1,RFC10 2 RF Choke, 100 µH ("101"), black body, 0.75" LS E690017 RFC3-RFC5,RFC11 4 RF Choke, 100 µH (BRN-BLK-BRN), tan body, 0.4" LS E690016 RFC6,RFC7,RFC8 3 RF Choke, 100 µH, miniature (BRN-BLK-BRN), tan body, 0.2" LS E690013 RFC9 1 RF Choke, 15 µH, miniature (BRN-GRN-BLK), tan body, 0.2" LS E690012 RP1 1 Resistor network, 3.9 k, 8 pins (marked part number should include "392") E510000 SP1 1 Speaker, 4 ohms, 3W E980007 T1 1 Transformer, small binocular toroid core (gray, approx. 0.5" x 0.75") E680014

E500059

T2 1 Transformer, large binocular toroid core (gray, approx. 1" x 1.2") E680015

T3 1 Transformer, FT37-61 toroidal core (gray, 0.37" dia.) E680002

Page 8

Picture Ref. Designator(s) QTY Description Part #

T4 1 Transformer, FT50-43 toroidal core (gray, 0.5" dia.) E680008 U1 1 IC, PIC16F872 microcontroller, pre-programmed, KPA100 E610011 MISC 1 Socket for U1, 28 pins E620011 U2 1 IC, octal peripheral driver, TD62083AP (alt: ULN2803) E600040 U3 1 IC, 5-volt regulator, 78L05 E600029 U4 1 IC, RS-232 driver/receiver, MAX1406CPE (alt: LT1039CN16) E600036 U5 1 IC, dual op-amp, LM358AN E600010 U6 1 IC, high-current op-amp w/enable, EL5146CN E600041 U7 1 IC, dual op-amp, rail-to-rail, LMC6482AIN E600011 X1 1 Crystal, 16.289MHz, low profile ("S162ECSL") E660014 X2 1 Crystal, 4 MHz ("4.00-20") E660006 Z1 2 Ferrite beads, 0.23" (6 mm) long; two beads on a 1N4007 diode lead) E980029 HDWR 2 Fuse holder housing, twist-lock (for external 20A fuse) E980047

HDWR 2 Fuse holder contacts, #12 size E980048

HDWR 1 Fuse holder spring, for 1.25" long fuse E980049

HDWR 2 Fuse, 20A, Littlefuse #312020 or equivalent (1 spare) E980050

HDWR 2 Standoff, M-F, 3/16 dia. x 3/16" long hex 4-40 thd (for J8) E700052 HDWR 5 Standoff, 3/16 dia. x 3/16" long hex 4-40 thd (between PCB and heat sink) E700068 HDWR 2 Standoff, 3/16 dia. x 1/2" long hex 4-40 thd (between PCB and shield) E700061 HDWR 5 Standoff, 3/16 dia. x 5/8" long hex 4-40 thd (between PCB and shield) E700060 HDWR 14 Screw, 4-40 x 3/16" pan head, black anodized (2 spares) E700015 HDWR 5 Screw, 4-40 x 3/16" undercut flathead, black anodized (1 spare) E700025 HDWR 19 Screw, 4-40 x 1/4" panhead (2 spares) E700005 HDWR 3 Screw, 4-40 x 1/4" flathead (1 spare) E700063 HDWR 5 Screw, 4-40 x 9/16" undercut flathead (1 spare) E700064 HDWR 8 Set screw, 4-40 x 1/2", .05" hex socket head, stainless steel (1 spare) E700066 HDWR 12 Nut, 4-40 small pattern (2 spares) E700055 HDWR 1 Nut, 6-32 hex, stainless steel (for GND screw) E700069 HDWR 33 Lock washer, #4 split (3 spares) E700004 HDWR 2 Flat washer, #6, Stainless Steel E700067 HDWR 1 Solder lug (used for grounding J2) E700062

Page 9

Picture Ref. Designator(s) QTY Description Part #

HDWR 1 Thumbscrew, 6-32 x 1/2", black plastic knob (for GND screw, E1) E700070

HDWR 5 Fibre washer for speaker, #4, .047" thick x 0.25" dia. (1 spare) E700028 MISC 1 Heat sink, KPA100, approx. 7.6" W x 6" L (19.23 x 15.2 cm) E100127

MISC 1 Shield, KPA100, approx. 7.3" W x 6" L (18.5 x 15.2 cm) E100137

MISC 1 PC board, KPA100 E100134 MISC 1 Top cover trim panel, KPA100, painted (wrapped in paper) E100135 MISC 1 Rear panel, KPA100, painted and silk-screened (wrapped in paper) E100136 MISC 1 Grille cloth, black, approx. 3 x 3" (7.5 x 7.5 cm) E980053 MISC 2 Thermal pad for flange-mount power transistor (Q1 and Q2) E980051

MISC 2 TO-126 thermal pad, self-adhesive (Q3, Q4) E980052

MISC 1 BNC connector cap, plastic (to cap K2's BNC antenna jack) E980006 MISC 26 ft. Enamel wire, #22 red (for all lowpass filter toroids and L18) E760018 MISC 9 ft. Enamel wire, #26 red (for T3, T4, L15, L16) E760002 MISC 3 ft. Enamel wire, #26 green (for T3 and T4) E760004 MISC 5 ft. 2-conductor wire, #12 stranded, red/black (for DC power wiring) E760017 MISC 1 ft. RG174 coax (for RF cable to K2 RF board) E760010 MISC 1 10-conductor ribbon cable with pre-installed connectors; 4" long E980045 MISC 1 ft. 2-conductor speaker cable, #24 stranded (for J5 and speaker) E760012 MISC 10 ft. 4-conductor shielded cable (serial I/O cable) E760009

Page 10

Picture Ref. Designator(s) QTY Description Part #

MISC 1 ft. Stranded insulated hookup wire, #20 black (for DC cable to K2 RF board) E760006 MISC 1 ft. Stranded insulated hookup wire, #20 red (for DC cable to K2 RF board) E760007 MISC 1 ft. Hookup wire, #24, solid conductor, green ins. (for K2 Control board mod) E760008 MISC 1 ft. Stranded, Teflon-insulated wire, #22 gray (for T1) E760020 MISC 2 ft. Stranded, Teflon-insulated wire, #18 gray (for T2) E760021 MISC 3 Cable tie, 3" E980002 MISC 1 Allen wrench, .05", short handled (for 1/2" heat sink set screws) E980008 MISC 1 Sand paper, 180-grit (for heat sink preparation) E980055

Page 11

Assembly, Part I

Downloaded by

RadioAmateur.EU

Place the KPA100 PC board as shown in Figure 1, and identify the top side, which has most of the components. (A complete parts placement drawing can be found at the end of this appendix.) The "Front Edge" and "Back Edge" designations are based on the board's orientation when installed in the K2.

With the bottom side of the board facing you (speaker cutout at the upper right), locate the position for resistor R28, along the back edge, far right. The label "R28" is just above of the resistor’s outline.

Install a 200-ohm, 1-watt resistor (red-black-brown) at R28. Form the leads to fit the given pad spacing. Bend the leads to hold the resistor in place. Note: It's a good idea to orient all resistors in one direction for ease in reading the color codes later. Orient R28 with its first color band (red) toward the left.

Back Edge

KPA100 REV A

(Top Side)

Figure 1

Front Edge

Make sure R28 is seated flat on the board, with no excess lead length exposed. This is necessary to keep the resistor from touching the heat sink, which will be attached later.

Solder R28 from the top side of the board. Do not use an excessive amount of solder. Trim the leads to about 1/16" (1.5 mm) or shorter.

If your solder joints are not clean and shiny, your iron

may not be hot enough, or you may be using the wrong type of solder. These "cold" solder joints will likely result in poor

performance, reliability problems, or component failure. Before proceeding, consult our web site for additional

soldering instructions and tool recommendations.

Page 12

On the top side of the board, locate the component outline for .005-ohm current-sensing resistor R7 (near the DC power connector, J3). Each of R7's pads has three holes.

The leads on small capacitors are fragile. Do not pull

on the leads or bend them excessively.

Bend the leads of the .005-ohm, 3-watt resistor to match the spacing between R7s innermost pair of holes (see Figure 2a). Install the resistor, pressing it down onto the board as far as it will go.

On the bottom side, fold R7's leads outward so they lay flat against the pads (Figure 2b). Trim the leads to match the size of the pads. Solder each lead over the full length of the pad.

Note: Components may be soldered one at a time or in groups. Leads can be trimmed either before or after soldering. Flush trimming (trimming very close to the board) is required only when specified. Otherwise, trim leads to about 1/16" [1.5 mm] or less in length.

(a)

(b)

Sort all capacitors into groups by capacitance value. Start by

grouping them by physical appearance (size, color, etc.).

In all cases where two or more capacitor types have the same value, further sort them by lead spacing and voltage rating. The parts list provides identification details for specific capacitor types.

Locate an 0.1- µF ("104") capacitor with 0.1" lead spacing for use at C75.

Install C75 at its indicated location on the bottom of the board, near the back edge. The capacitor must be seated as close to the board as possible, with 1/16" (3 mm) or less lead length exposed. Remove any U-shaped bends or folds using long-nose pliers. Solder C75 from the top side of the board.

Install a .01-µF ("103") capacitor with 0.1" lead spacing at C65. C65 is located on the bottom side of the board, near the front edge. Keep the lead length short, as described in the previous step.

Figure 2

Page 13

The color bands on 1/4-watt 1% resistors can be difficult to read. Use a DMM (digital multimeter) to verify the values of all these resistors. Tape them to a piece of paper with their values labeled.

Install the resistors listed below on the top side of the board. Start with R3, which is at the front edge of the board, near the "KPA100" label.

In general, assembly proceeds from left to right and from front edge to back edge on the PC board.

__ R3, 2.7 ohms, 1/4 W (red-violet-gold) __ R24 and __ R25, 8.45 k, 1%, 1/4 W (gray-yellow-green-brown) __ R15 and __ R16, 3.3 k, 1/4 W (orange-orange-red) __ R31, 200 ohms, 1 W (red-black-brown) __ R4, 100 k, 1/4 W (brown-black-yellow) __ R10, 47 ohms, 1/4 W (yellow-violet-black) __ R5, 15 k, 1/4 W (brown-green-orange) __ R8, 10 k, 1/4 W (brown-black-orange) __ R30, 3.09 k, 1% (orange-black-white-brown) __ R32, 100 ohms, 1%, 1/4 W (brown-black-black-black)

__ R14, 470 ohms, 1 W (YEL-VIO-BRN) (located near back edge) __ R11, 510 k, 1/4 W (green-brown-yellow) __ R12, 180 k, 1/4 W (brown-gray-yellow) __ R13, 100 ohms, 3 watts __ R1, 3.3 k, 1/4 W (orange-orange-red) __ R2, 2.7 ohms, 1/4 W (red-violet-gold) __ R29, 3.3 k, 1/4 W (orange-orange-red), location: far left, near small notch

Install RFC11 on the bottom side of the board. Its location is

close to the cutout for power transistor Q1.

Make sure RFC11 is pressed against the board as far as it will go,

then solder it from the top side of the board.

Install and solder the RF chokes listed below. Limit soldering time on miniature chokes (2 to 3 seconds per lead). All chokes are on the top side of the board near connectors J3 and J8.

__ RFC9, 15 µH, miniature (brown-green-black) __ RFC6, __ RFC7, __ RFC8, 100 µH, miniature (brown-black-brown) __ RFC3, __ RFC4, __ RFC5, 100 µH, small (brown-black-brown) __ RFC1, 100 µH (101), large

Check the resistance across each RF choke using the lowest resistance scale of your DMM. This will ensure that the chokes were not damaged during soldering. All readings should be under 10 ohms.

Sort all of the diodes according to type. Use a magnifying glass if necessary to positively identify glass diodes (1N4148 and 1N5711).

Install diodes D1-D8 (1N4148) on the bottom side of the board, near the large cutout, but do not solder yet. Bend the leads very close to the body to fit the given pad spacing. The banded end of each diode (cathode) must be aligned with the band on its component outline.

Make sure D1-D8 are seated as far down on the PC board as possible. Solder and trim the leads.

Sort all of the RF chokes by size and value. Do not pull on the

leads, which are fragile and can be easily damaged.

Locate a small 100-µH RF choke for use at RFC11 (tan body, BRN-BLK-BRN color code, 0.4" lead spacing). Do not use one of the miniature 100-µH RF chokes, which has a much smaller lead spacing.

Page 14

Install the remaining diodes on the top side of the board. Start

with D17, at the lower left-hand corner near the small notch.

__ D17, 1N5711 __ D16, 1N5711 __ D10, 1N5404 __ D13, 1N5404

Use a ruler to check the height of all capacitors just installed, as well as C65 (near the front edge) and C75 (near the back edge). If any capacitor body extends to 3/16" (4.5 mm) or more above the surface of the board, fold it down toward the board. The capacitors should not touch any adjacent pads.

Note: D14, 12, and 11 are not all oriented in the same direction

__ D14, 1N4007 __ D12, 1N4007 __ D11, 1N4007

(Save the 1N4007 leads for use as jumpers, etc., in later steps)

__ D9, SB530

Using the diode check scale on your DMM, test all of the diodes on the board. (This will ensure that diodes have not been damaged during installation.) First, touch the red (+) lead of the DMM to the anode (non-banded end), and the black (-) lead to the cathode (banded end); the meter should indicate a forward voltage in the range of 0.1 to

0.7 volts, varying with diode type. Next, reverse the leads; the DMM should show an open-circuit indication (flashing "3.000" or "0.000," etc.).

Near the "ELECRAFT" label, you’ll find a short jumper location,

identified by a ground symbol ( ). Use a discarded 1N4007 diode lead to make a 3/4" (19 mm) U-shaped wire for this jumper. Mount the

jumper on the top side of the board, with the top of the U-shape approx. 1/4" (6 mm) above the board. Solder it from the bottom side.

Install the following capacitors on the bottom side of the PC board, but do not solder yet. Capacitors must be seated as close to the board as possible. About 1/16" (3 mm) of lead length may remain exposed. Remove any U-shaped bends or folds using long-nose pliers.

Note: These capacitors are all .01 µF (103), with 0.1" lead spacing.

Solder the capacitors from the top side. Use just enough solder

to fill the hole, since the leads will be flush-trimmed in the next step.

Important: Relays K1-K12 will be installed on the top side of

the board, opposite capacitors C13-C22 and C29. This requires that the capacitor leads and their surrounding solder filets be trimmed as close to the PC board as possible.

Flush-trim the leads of C13-C22 and C29 on the top side of the board. After trimming, the leads and surrounding solder filets should be no more than 1/32" (0.8 mm) high.

Install the 0.2" lead spacing capacitors listed below on the top side of the board. Start with C11, which is along the front edge of the board near the "KPA100" label.

__ C11, 0.1 µF (104) __ C23, 0.1 µF (104) __ C25, .001 µF (102) __ C68, .01 µF (103) __ C89, .01 µF (103)

__ C26, 33 pF, 50V (Do not confuse with C5F, rated at 500 V or 1 KV) __ C41, 100 pF (101)

__ C38, .01 µF (103) __ C39, .01 µF (103) __ C37, .01 µF (103) __ C36, 0.015 µF (153, 15N) __ C35, 0.1 µF (104) __ C44, .01 µF (103) __ C42, 0.015 µF (153, 15N) __ C43, 0.015 µF (153, 15N) __ C46, .01 µF (103) __ C40, 0.1 µF (104)

__ C99 ⇒ __ C97 ⇒ __ C98 ⇒ __ C22 __ C74 __ C29 __ C13 __ C15 __ C17 __ C19 __ C21 __ C14 __ C16 __ C18 __ C20

Page 15

Place relays at locations K1-K12, excluding K3. (K3 will be installed after the output transformer, T2.) Each relay can only be installed one way; the white mark on the relay must be oriented as indicated by the mark on the component outline. Do not solder the relays yet, and do not clip or bend the relay leads.

Inspect each relay to make sure that it is seated flat against the board. If not, remove it and flush-trim the leads which are preventing it from sitting flat against the board.

Make sure that you have not installed relay K3.

Using a book or other flat object to hold the relays in place on the top side of the board, flip the board over. Solder two diagonal corner pins on each relay.

Inspect the 11 relays closely to make sure that they’re seated flat against the PC board. If not, re-heat the corner pins one a time while pressing down on the relay. Once all relays are properly seated, solder the remaining pins. Do not trim relay leads, which can cause

mechanical stress, reducing the life of the relay.

Install the small capacitors listed below. (The first capacitor in

the list, C50, is near trimmer C27). Lead spacing (LS) and voltage

are shown where required to identify the capacitor type.

__ C50, .01 µF (103), 0.1" LS __ C30, 0.1 µF (104), 0.1" LS __ C33, 0.1 µF (104), 0.1" LS __ C34, 0.1 µF (104), 0.1" LS __ C61, .047 µF (473) __ C62, .047 µF (473) __ C63, .047 µF (473) __ C70, .001 µF (102), 0.2" LS __ C69, .001 µF (102), 0.2" LS __ C55, .047 µF (473) __ C56, .047 µF (473) __ C57, .047 µF (473)

__ C54, .047 µF (473) __ C53, .047 µF (473) __ C52, .047 µF (473) __ C49, .047 µF (473) __ C48, .047 µF (473) __ C31, .033 µF (333, 33N) __ C86, .047 µF (473) __ C76, .01 µF (103), 0.1" LS __ C67, .033 µF (333, 33N) __ C77, .015 µF (153, 15N)

__ C82, 1200 pF (122), 50V (do not confuse with 1200 pF, 500-V mica) __ C66, 180 pF (181)

__ C28 .01 µF (103), 0.1" LS (far left side of the board near K4) __ C12, .01 µF (103), 0.1" LS

Install resistor network RP1 near the "KPA100" label at the front edge of the board. The dotted (pin 1) end of RP1 should be oriented to the left. (RP1 is symmetrical and can be reversed, but this orientation will help visually identify the pin 1 end.)

Install trimmer potentiometers R26 and R27 (100 k, "104") near the speaker cutout. The trimmers will sit a small distance above the PC board on the pin shoulders. Set the trimmers to their midpoints.

Install trimmer potentiometer R6 (1 k, "102") at the right side of the board near T1. Set the trimmer fully counter-clockwise.

Install the 5 to 30 pF ceramic trimmer capacitors, C1 and C27. C1 is at the far left near the small notch. C27 is near the microcontroller, U1 (16F872). Orient the flat side of each trimmer as indicated.

Using a small flat-blade screwdriver, set both trimmers to their midpoints (screwdriver slot perpendicular to the flat side).

__ C95, 100 pF (101) (near small notch and T4)

__ C88, .001 µF (102), 0.2" LS __ C87, .001 µF (102), 0.2" LS __ C24, .01 µF (103), 0.1" LS __ C85, .047 µF (473) __ C90, .01 µF (103), 0.2" LS __ C71, .0018 µF (182), 0.2" LS __ C72, .01 µF (103), 0.1" LS __ C73, .01 µF (103), 0.1" LS

__ C10, 0.1 µF (104), 0.2" LS __ C32, .01 µF (103), 0.1" LS __ C7, .01 µF (103), 0.1" LS __ C8, .01 µF (103), 0.1" LS __ C9, .01 µF (103), 0.1" LS __ C84, .001 µF (102), 0.1" LS

Page 16

Install the low-pass filter capacitors listed below. All are 500 V or 1KV (1000 V) disc, with 0.2" lead spacing. These capacitors are located on the left side of the board between the two rows of relays (K3-K12).

Note: Some of these capacitors are arranged in close-spaced groups of three on the board. Look at all of the reference designators in a

group to be sure you know which capacitors they refer to.

__ C5B, 18 pF (may have black band on top and no marked voltage) __ C3B, and __ C4B, 27 pF __ C5F, 33 pF (Do not confuse with C26, which is 33 pF, 50 volts) __ C3H, 39 pF __ C5D, 47 pF __ C4D, 56 pF (may have black band on top and no marked voltage) __ C5A, 68 pF __ C6C, 68 pF (note: C6D pertains to the large cap to the left of C6C) __ C3E, and __ C5G, 82 pF __ C4E, 120 pF (121) __ C3G, __ C4A, __ C5C, __ C5E, and __ C6E, 150 pF (151) __ C2B, __ C3C, and __ C3J, 220 pF (221) __ C3A, __ C3D, __ C4C, and __ C6F, 270 pF (271) __ C3F, __ C6A, __ C6B, and __ C6G, 330 pF (331) __ C2D, 390 pF (391)

Install the 4 MHz crystal (X2) near the microcontroller (U1).

X2 must be seated flat against the board, with no insulators or other spacers, or the metal shield will not fit correctly.

Cut two 3/4" (19 mm) bare wires (use small component leads).

Insert a bare wire into the grounding hole provided just to the left

of X2. Solder this wire to the side of the crystal can, not the

top, or it will prevent installation of the shield in a later step.

Keep soldering time below 5 seconds; if it takes longer, your iron may not be hot enough, or your iron tip may not be making good contact with the crystal can.

Turn the board over, then solder and trim X2's ground wire.

Ground crystal X1 using the second bare wire. X1 is low profile, so

the wire can be soldered to the top of the can. Avoid overheating.

Install the 10-pin, dual-row (5x2) male connector at P1, but do not solder yet. Figure 3 shows P1 as viewed from right side of the board. The plastic part of the connector must be on the top side of the board, with the long end of the pins pointed up. The short ends are inserted into the board.

Install the .039 µF capacitor, C79 (0.4" lead spacing, "393" or

".039 µF" label). C79 is located near relay K2.

Install a .0018 µF ("182") capacitor with 0.4" lead spacing at

C64. C64 is located near relay K2.

Install the electrolytic capacitors, C51 and C60. C51 (470 µF) is near the large transformer, T2. C60 (100 µF) is near T1. The (+) lead must be installed in the hole marked with a "+". The (+) lead is usually longer than the (–) lead, and the (–) lead is identified by a black or white stripe.

Install the low-profile 16.289 MHz crystal ("S162ECSL") at X1, near the speaker cutout. Make sure the crystal is seated flat against the board, then solder. Use a minimum amount of solder to avoid a short under the can. Note: Insulators are not needed for crystals. The solder mask on the top of the board provides adequate insulation.

Figure 3

Solder just one pin of P1, from the bottom side. Note: P1's plastic body can melt if too much heat is applied, causing the pins to be mispositioned. Limit soldering time to 2 to 3 seconds.

Examine the placement of P1. If it is not flat against the board, re-heat the soldered pin while pressing down on the connector.

Once P1 is in the right position, solder the remaining pins. Do not trim the leads.

Page 17

Install a 2N3904 transistor at Q8, near X1. (Use a magnifying glass if necessary to identify TO-92 package transistors.) The flat side of the transistor must be oriented toward the flat side of its outline as shown in Figure 4a.

ZVN

(a)

(b)

Figure 4

4424A

MOSFET transistors Q6 and Q7 (ZVN4424) have a modified

TO-92 package that must be oriented as shown in Figure 4b. The

labeled side of these transistors faces away from the flat side of the outline. Install and solder Q6 and Q7, which are located

between relays K1 and K2.

Q9 is a TO-220 package MOSFET (IRF830 or IRL620) with a metal tab. The tab may have been cut off already. If not, you'll need to trim it. Using heavy wire cutters or tin snips, cut off most of the tab (see Figure 5). This is necessary to prevent the tab from shorting to the shield in later steps. Do not use flush cutters or other small

cutting tools to cut off the tab; this may damage the tool.

Install Q9 vertically as shown below. The transistor will sit above the board due to the shoulders on the leads. The tab must be oriented toward J7 as indicated by the component outline. Trim the pins on the bottom after soldering.

Install another 2N3904 at Q5, which is on the right side of the

board near potentiometer R6 (labeled "BIAS SET").

Install voltage regulator U3 (78L05), which has a 3-lead TO-92 package like the 2N3904 transistor. U3 is located in the right-front corner of the board near connector P1.

The MOSFET transistors to be installed in the following

steps can be easily damaged by static discharge. Before and during installation of these devices, touch an unpainted, grounded metal surface.

Install MOSFET transistors Q10, Q11, Q12 (2N7000), which are located near the "KPA100" label. The flat side of each transistor must be aligned with the flat side of its outline as shown in Figure 4a.

Shortened Tab

Back edge of PCB

Figure 5

Page 18

Transistor Q3 (MJE182) will be installed on the bottom side of the board, near the board cutout for power transistor Q2. Place the transistor over its outline, with the metal side of the package facing away from the board. Bend the three leads at right angles to

match the given pad locations, but do not solder yet. Note: the leads

will break if bent too many times.

Bend two opposite corner pins on the bottom side to hold the IC

in place. Solder all 8 pins (about 1 to 2 seconds per pin).

Install the ICs listed below. All are located to the right of U5. Compare the part number on the IC to the number printed on the board, and make sure that the pin 1 end is oriented correctly.

Insert Q3's leads into their holes. Center the transistor's plastic

body within its component outline. Re-form the leads if necessary.

Verify that Q3's metal side is facing away from the board, then solder the leads from the top side, keeping the transistor pressed down against the board.

Install Q4 in the same manner.

Before handling ICs, touch a metal surface. ICs

damaged by electrostatic discharge can become intermittent, and the resulting problems may be difficult to troubleshoot.

Note: The pin 1 end of ICs can be identified by a notch or dimple as

shown in Figure 6. This end must be oriented toward the notched end of the component outline.

Notch

Pin 1

Dimple

Pin 1

Figure 6

Install U5 (LM358, 8 pins), which is located on the top side of the board, left of the "KPA100" label. A portion of the part number is printed on the board under the IC ("358"). Do not solder yet.

__ U2, TD62083 __ U6, EL5146 __ U4, MAX1406 __ U7, LMC6482

Install the 28-pin IC socket at U1. The notched end of the socket

must be aligned with the notched end of its outline.

In the following steps you'll be installing several

connectors at the back edge of the PC board (top side). These connectors must be installed correctly in order for the rear panel to fit onto the PC board. Figure 32 (page 38) shows how the

rear-panel connectors will appear once installed.

Install the external speaker jack, J6, at the back edge of the board. Solder the center pin only. Make sure that the jack is pressed down flat against the board while soldering.

If J6 does not appear to be aligned with its PC board outline, or it is tilted, re-heat the center pin while adjusting the connector's position. Once it is positioned correctly, solder the other two pins.

Locate screw terminal E1. If it was supplied with a screw, remove it. The screw will not be used.

Place E1 in its indicated position, with the threaded hole facing the rear edge of the board. Solder just one pin. CAUTION: This part will get hot; don’t touch it with your finger while soldering.

If necessary, reheat the soldered pin of E1 and adjust it so that all four pins are pressed down on the board as far as they'll go. Then solder all pins.

Page 19

Install the RCA jack, J7. The small plastic standoffs on the bottom of the connector should be inserted in the holes provided. While soldering, hold J7 flat against the board, and keep it centered within its component outline. Clip the leads on the bottom side.

Locate J8, the 9-pin "D" connector, and temporarily place it in its indicated location (far right side of the board). Note that the leads of capacitors C97-C99 on the bottom of the board interfere with the proper seating of J8. To avoid this, you will need to trim off the plastic extensions on both sides of the connector. First, bend upward and cut off the thin metal tabs above the plastic extensions (do not use flush cutters for this--you may damage them) . Then trim the plastic away so that it doesn't interfere with the leads of C97-C99.

Install J8 and solder just one of the 9 pins. Adjust the position of J8 as you did for the other connectors, making sure the connector is flat against the board. Then solder the remaining pins.

You may have received two 16F872 microcontrollers with

your kit. The one marked "KPA100" or "PA" should be used here.

Before handling U1 (16F872), touch a grounded surface.

Straighten the leads of U1 (PIC16F872) as shown below. The rows of pins must be straight and parallel to each other to establish the proper pin spacing. To straighten the pins, rest one row of pins against a hard, flat surface. Press down gently on the other row of pins and rock the IC forward to bend the pins into position as shown below.

Insert U1 into its socket, with the notched or dimpled end of the

IC aligned with the notched end of its component outline.

Examine U1 closely. If any pins are bent, remove the IC and straighten them. (To remove U1 from its socket, pry it up gently on each end using a small flat-blade screwdriver.)

Visual Inspection

Nearly all problems with kits are caused by poorly-

soldered component leads or incorrectly-installed components. You can locate and correct most assembly errors ahead of time with a simple visual inspection. This is especially important at high power levels, where an unsoldered or reversed component could cause damage to the power transistors.

closely for all of the following: cold solder joints (dull rather than shiny appearance), solder bridges, and leads that are not soldered. Reheat any suspect joints.

re-check the orientation of all __ Diodes, __ Transistors, __ ICs.

Using a magnifying glass, examine the bottom of the PC board

Using the parts placement drawing at the end of the appendix,

Flared

Straight

Figure 7

Page 20

Initial Tests

Make the resistance measurements listed below, touching the DMM's (+) and (-) leads to the indicated points. The (-) lead will go to ground in all cases except the first measurement (relay coils).

The symbol > means greater than. Your DMM may indicate

infinite resistance (all digits flashing) for readings that are listed as "> 10 k." (Do not use an analog VOM.) Other readings should be +/- 10 %. K4 reads higher resistance than the other relays because K3 is not yet installed (the two coils are in parallel).

KPA100 Test Points (+, -) Resistance

(+) and (-) leads of relays K1,K2,K4-K12

(on bottom of board, marked)

U1 pin 1, ground > 1 k U1 pin 2, ground > 10 k U1 pin 3, ground > 10 k

U1 pin 4, ground 3.1 k U1 pin 13, ground > 10 k U1 pin 14, ground > 10 k U1 pin 27, ground > 10 k U1 pin 28, ground > 10 k

U4 pin 1, ground > 10 k

U4 pin 8, ground > 10 k

"AF" pad (measure from bottom), ground > 10 k

D10 banded end, ground > 10 k

Determine what revision of firmware your K2 has installed at present by turning the K2 on while holding any switch. Record the number shown at the left end of the LCD (e.g., 2 . 0 1 H ): _______.

Turn off the K2. Disconnect all external cables.

Remove the six K2 top cover screws shown in Figure 8.

Remove the top cover. Disconnect the speaker and all options.

Store the top cover in a safe place to protect the finish.

650-800 (K4)

325-400 (others)

You can easily remove the KPA100 and re-install the original

top cover at any time, returning the K2 to its low-power field configuration.

1 2

3 4

5 6

Figure 8

Before handling the Control board in the following

steps, touch a grounded surface.

panel board. Also remove the KAF2 audio filter board if present.

the Control board up at the point marked "LIFT HERE" on the RF board. Then unplug the Control board. Place it in front of you with the component side up.

the voltage selector switch, S1. If the present value of this capacitor is .01 µF ("103"), replace it with an 0.1 µF capacitor ("104"). Use a capacitor with 0.2" lead spacing. Note: If you have an older Control board (rev XC) that does not include C42, solder the 0.1 µF capacitor between pins 4 and 8 of U3 (LMC6482, on the Control board).

Remove the screws that hold the K2 Control board to the front

Use the long-handled Allen wrench supplied with the K2 to pry

Locate C42 on the K2 Control board (CTRL-C42), which is near

Page 21

A ribbon cable is used to connect the KPA100 board to the K2

Control board. To ensure correct cable orientation, keying inserts are used. This requires cutting one pin on the male connectors at each end. The pin to be cut, 8T (8-volt transmit), is not used by any Elecraft option. If you need 8T for any reason, skip the next three steps, as well as the last step on this page.

The main microcontroller (U6, K2 Control board) must

have revision 2.02A or later firmware in order to control the KPA100. If your firmware revision (recorded on the previous page) is

older than this, you'll need to install a new microcontroller. This 40pin IC should have been supplied with your KPA100 kit. Refer to the K2 Revision 2 Firmware manual for installation instructions.

Locate P4 on the Control board, a 10-pin, dual row (5 x 2) male connector (see Figure 9). P4's pins are numbered left to right, top to bottom (pin 2 is to the right of pin 1, pin 3 is below pin 1, etc.).

Cut Pin 4

Figure 9

Cut pin 4 of P4 as indicated above, as close as possible to the connector's plastic body. The best way to do this is to grasp the pin with long-nose pliers, then bend it repeatedly until it breaks off.

Cut pin 4 of P1 on the KPA100 board (see Figure 10).

Cut Pin 4

If you plan to use computer control of your K2 via the KPA100's RS232 interface, and have not previously installed the KIO2 option, you may need to modify the Control board (see page 51). Making the modification now will save you the trouble of removing the Control board again later.

Plug the K2 Control board into the RF board. Make sure that all three connectors along the bottom edge of the board are plugged into their mating connectors.

Re-install the KAF2 board if applicable. Secure the Control board to the Front Panel board with the hardware removed earlier.

Locate the pre-assembled ribbon cable. Lay the cable flat as

shown in Figure 11, with the black wire at the top and the

connector holes facing up.

Black Wire

R31

C25

Figure 10

Pin 1 Mark

GNDAF

Pin 1 Mark

Figure 11

Install keying inserts in position 4 of both connectors. The inserts include break-off tabs that aid installation. The inserts should lock in place and be flush with the mating surface of the connector.

Page 22

The cables that connect the KPA100 to the K2 are all kept

short to avoid pickup of stray RF. Because of this, the KPA100 assembly must be placed on top of a 3 to 4 inch (7 to 10 cm) platform to the right of the K2 during test and alignment. You can use books, a cardboard box, etc. Do not use metallic objects.

Place the KPA100 on a suitable platform as described above. The front edge of the KPA100 board should be facing toward you (speaker cutout to the right).

Plug one end of the ribbon cable into the Control board at P4. The correct end can be determined from Figure 12. The black wire should be oriented toward the lower end of P4 (away from pin 1). If the indicated end of the ribbon cable cannot be plugged in at P4, the keying insert may be installed at the wrong position.

GND

12 K2

Pin 1 Mark

Black Wire

Figure 12

Plug the other end of the ribbon cable into the KPA100 at P1. The correct orientation is shown in Figure 13.

The SSB option microcontroller (U1, KSB2) must have revision 1.06 firmware or later. Check the label to determine the revision. If it's older than 1.06, a new 28-pin IC (16C72A or 16F872) should have been supplied with your KPA100 kit. Install it at this time, with pin 1 of the IC oriented toward the left side of the K2.

Ribbon Cable To Control

Board, P4

SPKR

GND

Figure 13

Connect a 12-14 volt power supply or battery to the K2's DC

input jack (DC barrel connector, J3 on the RF board).

Turn on the K2; you should see E L E C R A F T on the LCD, followed by N O P A P S . This message is a reminder that no high- current power supply is connected to the KPA100 yet. You may also hear relays switching on the KPA100 (in addition to the K2 relays).

Tap D I S P L A Y to check the K2 power supply voltage (E) and current (i). If the voltage is lower than expected, or the current is over

0 . 5 0 amps, refer to Troubleshooting (page 56 of this appendix). Note: Installing the KPA100 increases K2 receive-mode current drain by approximately 100-200 mA. In transmit mode, additional current is drawn, but this will not be included in the voltage/current display.

Tap D I S P L A Y until the frequency display returns.

Page 23

Set your DMM for DC volts, 20 or 30 V full scale (or auto

Downloaded by

RadioAmateur.EU

ranging). Connect the DMM's (-) probe to the ground jumper on the KPA100 board (near U1). Using the DMM's (+) probe, make the voltage measurements listed below. Voltages should be within +/- 10% except as noted.

When making measurements at IC pins, be careful not

to short adjacent pins. Use only a fine-tip DMM probe. Do not attempt to make measurements using a wire or a probe with a large, blunt tip.

KPA100 Test Point (+) Voltage

U1 pin 1 5.0

U1 pin 7 0 to 0.1 U1 pin 13 0 to 0.1 U1 pin 14 0 to 0.1 U1 pin 15 0 to 0.1 U1 pin 20 5.0 U1 pin 27 5.8 U1 pin 28 5.7 U2 pin 10 12-15

U4 pin 1 12-15 U4 pin 11 5.0

U5 pin 1 0 to 0.1

U5 pin 7 0 to 0.1

U6 pin 1 0 to 0.1

Tap M E N U , then tap D I S P L A Y to bring up the K2's secondary

menu (S E C will be flashed). This menu is used to configure various features that are available in K2 revision 2 firmware.

Use the VFO knob or the B A N D + / B A N D - switches to scroll to

the P A menu entry. If you see P A - - , the KPA100 microcontroller is not communicating properly with the K2. Refer to Troubleshooting.

The P A parameter will probably be set to O F F initially. Hold

E D I T to highlight the parameter, then scroll until you find an entry

starting with E (error status). The error status should be E 1 2 , where 1 indicates that the KPA100 is in bypass (QRP) mode, and 2 indicates that no KPA100 power supply is present. If you see any other error numbers, see Error Status in the Troubleshooting section.

Set the P A parameter to O N . Tap M E N U to return to menu

scroll mode.

Tap D I S P L A Y to return to the primary menu (P R I will be

flashed). Tap M E N U again to return to the normal frequency display.

Turn off the K2 and disconnect the power supply.

Disconnect the KPA100 end of the ribbon cable.

Page 24

Assembly, Part II

A number of toroidal inductors are used on the KPA100 PC board. The first inductor to be wound uses a type T44-2 core. The letter T identifies an iron-powder core. 44 specifies the outside diameter in hundredths of an inch, in this case 0.44 inches (11.2 mm). The -2 suffix refers to the core type and color, in this case a red iron-powder core.

There are also two ferrite toroid cores used, such as type FT37-61. In this part number, FT identifies the core as ferrite, and 37 is the size (0.37", 9.5 mm). The -61 identifies the type of ferrite, although all the ferrite cores are dark gray in color. (There are also two "binocular" ferrite cores in the kit, which will be described later.)

Three types of enamel wire are supplied with the kit: #22 red, #26 red, and #26 green. #22 wire is much larger in diameter than #26. Be sure to use only the type called for in the instructions; do not substitute other wire types. Cut wires to the specified lengths to avoid running out of wire.

Cut 13 inches (33 cm) of #22 red enamel wire. To wind L18, "sew" the long end of the wire through the T44-2 core. Each pass through the core counts as one turn. 14 turns are needed, as shown in Figure 14. The enamel insulation will be removed in a later step.

Remove insulation

Figure 14

Seven red iron-powder toroid cores are supplied with the kit. Four of these are type T50-2 (0.5" [12.7 mm] dia.), and three are smaller, type T44-2 (0.44" [11.2 mm] dia.). Locate a T44-2 core for use at L18.

Find the component outline for L18, at the right side of the board near the cutout for power transistor Q1. Compare this component outline to Figure 14, which shows two views of a typical toroidal inductor. L18 will be mounted vertically as shown at the right side of the drawing, with one wire exiting at the core’s upper left, and the other at the lower right.

#22 enamel wire is fairly stiff, and may be difficult to

wind tightly onto the core. The turns should not be loose, but it is acceptable to have a very small gap between the wire and the core's flat surfaces. If you try to wind #22 so that it "hugs" the core all the away around, you may have to pull the wire too hard, resulting in hand fatigue.

Pre-wound toroids are available from an Elecraft-approved source; see page 3.

Verify that the turns of L18 are not bunched together. They should be evenly spaced, and should occupy about 80-90% of the core. Typical turns spacing is shown in the photograph below (Figure 15).

Figure 15

Toroids shown in photos are wound on white cores to highlight turns counts and spacing. Place L18 on top of the photo above,

then adjust the turns spacing until it is similar to that shown.

Page 25

of solder (a "blob") on the end of your soldering iron, then insert the clipped end of the wire into the hot solder. If the iron is hot enough, you should see the insulation bubble after 4 to 6 seconds. Add more solder and feed more of the wire into it as the enamel melts. Continue tinning the wire up to slightly past the edge of the core. Then slowly pull the wire out of the solder. If any enamel remains on the lead, scrape it away using your thumb and forefinger. You can also burn the insulation off by heating it with a butane lighter for a few seconds, then use sandpaper to remove the enamel residue. If you scrape the insulation off with a razor blade, avoid nicking the wire.

from the leads up to the edge of the core (see Figure 14).

adhering very well, remove any residual enamel and re-tin the lead.

leads taut on the bottom of the board.

solder binds well to the leads. If the lead appears to be an "island"

in a pool of solder, it is not making good contact; remove the toroid and prepare the leads as described above. (For further

information, look for "Soldering Tips" on our web site.)

between L18's pads (not the leads) on the bottom of the board. If the reading is over 1 ohm, re-strip the leads. Note: Your DMM probes will have some residual resistance. Short them together to measure this amount, and subtract it from your continuity readings.

The enamel wire can be heat-stripped. Place a small amount

Strip the leads of L18 as described above. Remove the enamel

Tin L18's leads. If the solder on the leads looks dull or is not

Install L18 vertically as shown by its component outline. Pull the

Solder the leads of L18. When soldering, make sure that the

Do not apply adhesives or fixatives of any kind to toroids.

Using your DMM on a low resistance scale, check for continuity

__ L1: 27 T, RED __ L2: 25 T, RED __ L4: 17 T, BLK 22" (56 cm) 21" (53 cm) 15" (37 cm)

__ L5, 16 T, BLK __ L6, 16 T, BLK __ L7, 11 T, BLK 14" (36 cm) 14" (36 cm) 10" (26 cm)

__ L8, 10 T, BLK __ L10, 9 T, BLK __ L11, 8 T, BLK

9.5" (24 cm) 9" (23 cm) 8" (20 cm)

The low-pass filter toroids are shown in the photos at right (Figure 16). Wind each of these toroids using the indicated powderediron cores, either RED (T50-2) or BLACK (T50-10). All are wound using #22 enamel wire. Use the wire length and number of turns shown.

Prepare the leads of these toroids as you did for L18.

__ L12, 8 T, BLK __ L13, 21 T, RED 8" (20 cm) 18" (45 cm) 17" (43 cm)

Figure 16

L14, 20 T, RED

Page 26

Place each of the low-pass filter toroids on its photo and adjust the turns spacing so it is similar to that shown. Re-check turns counts and core colors. (Each pass through the core counts as one turn.)

Good electrical contact between toroid leads and their

pads is critical for safe and reliable operation at high power levels. If you see any indication that the solder is not binding well to a lead, remove the toroid and prepare the leads again.

Install L1 vertically as indicated by its component outline (near relay K3).

Prepare the leads of L15 and L16 as before.

Install L15 and L16, located near relay K2.

Locate the two dark gray (ferrite) toroid cores. The smaller of the two (type FT37-61) has a diameter of 0.37" (9.5 mm). This core will be used in the following steps.

Toroidal transformer T3 uses a bi-filar winding, which means that two wires are wound on the core together. The wires will be twisted together loosely before they're wound onto the core.

Install and solder the remaining low-pass filter toroids. Match each of the low-pass filter toroids to its reference designator carefully. Exchanging any of them will result in poor performance on two or more bands.

On the bottom side of the board, check for continuity between the pads of all the low-pass filter toroids. If you get a reading of > 1 ohm, remove the toroid from the board and prepare the leads again.

Two more T44-2 cores (red, 0.44" [11.2 mm]) will be used at L15 and L16. Cut two 24" (61 cm) lengths of #26 red enamel wire (the smaller gauge red enamel wire). Wind 29 turns on each inductor as shown in Figure 17.

Cut two 8" (20 cm) lengths of #26 enamel wire, one red and

one green.

Twist the red and green wires together over their entire length.

The wires should cross over each other about every 1/2" (1 cm).

Wind 7 turns of the twisted wires onto the small ferrite core (FT37-61). The turns should be spaced to cover about 80-90% of the core, as shown in Figure 18. Note: To make the turns spacing easy to see, the wires shown in the photo were not twisted together.

Separate T3’s leads as shown in Figure 19. The numbers on the leads correspond to numbered pads on T3's PC board outline.

Figure 18

Figure 17

Strip and tin the leads of T3. (Figure 18 shows T3 with its leads tinned.) Keep the red and green leads spaced slightly apart during stripping and tinning.

Page 27

Using a magnifying glass, examine the red/green lead pairs to

(GRN)

make sure that the leads are not shorting together near the core.

Install T3 vertically on the PC board as indicated by its outline (near the microcontroller, U1). Insert the red and green leads into their numbered holes as shown in Figure 19. Pull the leads taut on the bottom, then solder.

Separate T4’s leads as shown in Figure 21. The numbers on the

leads correspond to numbered pads on T4's PC board outline.

Figure 20

(RED)

Figure 19

Verify continuity between the #1 and #4 pads of T3. If you get a reading over 1 ohm, remove T3 and prepare the leads again.

Transformer T4 also uses a bifilar winding. Cut two 11" (28 cm) lengths of #26 enamel wire, one red and one green. Twist the red and green wires together as you did for T3.

Wind 12 turns of the twisted wires onto the large ferrite core (FT50-43). The turns should cover about 80-90% of the core, as shown in Figure 20.

Strip and tin the leads of T4. Using a magnifying glass, examine the red/green lead pairs to

make sure that the leads are not shorting together.

(RED)

Figure 21

Page 28

Install T4 vertically on the PC board as indicated by its outline near the small notch (back edge). Insert the red and green leads into their numbered holes as shown in Figure 21.

T4's leads are numbered differently from T3's. Be sure

to insert the leads into the correct numbered holes in the PC board, or the SWR bridge will not properly indicate forward and reflected power. This could result in damage to the power transistors.

Verify continuity between the #1 and #4 pads of T4.

Figure 22 (page 29) shows the connectors and other hardware that will be attached to the rear panel in the following steps. The antenna jack (J2), DC power jack (J3), and fan will be secured to the panel first, then the rear panel assembly will be attached to the KPA100 PC board.

Unwrap the rear panel. Orient it with the antenna jack at the left.

Always use bright (zinc-plated) hardware unless an item is described as black in the instruction step.

In the next step, do not use a small-gauge component

lead for Z1. Use a lead from a 1N4007 diode or 3-watt resistor.

Locate the two ferrite beads (gray). Slip the two beads onto a bare component lead (see above). Install this assembly at Z1, which is near the hole for RF power transistor Q1. Form the leads to match the indicated pad spacing.

Attach the antenna jack, J2 (SO239) to the rear panel as shown in Figure 22. Use four 4-40 x 1/4" (6.4 mm) pan head screws, one solder lug, three #4 split lock washers, and four 4-40 nuts. As shown in Detail A1, the solder lug takes the place of one lock washer. The lug must be installed on the screw nearest the top edge of the rear panel.

Do not overtighten the hardware.

Locate the four fan mounting holes (countersunk from the inside of the panel). Test a 4-40 flat-head screw at each screw location, and remove any burrs that might be obstructing flush seating of the screw head.

A small hole is provided near one of the countersunk holes for routing the fan wires. Insert the fan wires into this hole, and orient the fan as shown. The label side of the fan should face away from the panel.

Page 29

Downloaded by

RadioAmateur.EU

J7 J6

Fan Wires

BLK

RED

FAN

J8J3J2

RED

BLACK

GND

Figure 22

Page 30

Cut the two fan wires to a length of 2" (5 cm), measured from where they exit the fan's frame. Remove 1/4" (6.4 mm) of insulation from each wire, then twist together and lightly tin the strands.

Cut two lengths of #20 insulated hookup wire: one black, 1.5" (4 cm) long; and one red, 1.25" (3.2 cm). Remove 1/4" (6 mm) of insulation from each end of both wires.

Secure the fan to the rear panel using four 4-40 x 9/16" (14.3 mm) flat head screws, four #4 split lock washers, and four 4-40 nuts. Note: The screws may not extend through to the ends of the nuts, but the nuts should still be secure with 2-3 threads. Avoid tightening the screws further, as this could distort the fan's plastic frame.

Locate two DC input connector housings, one red and one black. Hold the two connectors in the orientation shown in Detail B1 of Figure 22. Look closely at the sides of the connectors. Each has a small tongue on the right side, and a groove on the left.

Slide the tongue on the right side of the red housing into the groove on the left side of the black housing. Make sure the housings are mated exactly as shown in Detail B1, with the black housing to the right and the "hoods" at the front of the connectors facing up. Make sure the interlocking tongue and groove are fully meshed.

Install right-angle PCB pins into the housings (Detail B2). The long end of the pin should be inserted into the housing until it snaps into position, and the short end must point down. When the pin is correctly inserted, the distance from the back end of the housing to the bend in the pin will be exactly 0.4" (10 mm).

Insert the paired housings through the rectangular rear-panel hole, with the red housing aligned with the "+" label.

Solder one end of the red wire to the center pin of the antenna connector (J2) as shown in Figure 22, Detail A2. Remove any excess solder from the outside of the pin using desoldering braid.

Solder one end of the black wire to the solder lug.

Make a 1" long jumper using a discarded component lead (from a small resistor or capacitor). Solder one end of this jumper to the center pin of J2, as close to the body of the connector as possible (Detail A2). Leave the other end free, oriented as shown.

Remove the finishing nut from the external speaker jack (J6).

Install the rear panel assembly onto the KPA100 PC board, threading J2's red wire through the center of transformer T4. At the same time, insert J3's leads into their holes.

Secure J6 (EXT SPKR) to the rear panel with its finishing nut.

Secure J8 (AUX I/O jack) to the rear panel using two male-female standoffs. Do not overtighten the standoffs.

Secure E1 (GND) to rear panel with the 6-32 thumbscrew, 6-32 nut, and two #6 flat washers. The nut must be installed between the washers and thumb screw as shown to ensure good electrical contact.

Use two E-shaped brackets to hold the housings in place, as shown in Detail B3 (one from above, one from below). Secure the brackets to the rear panel using two 4-40 x 1/4" (6.4 mm) flat head screws, two #4 split lock washers, and two 4-40 nuts. This hardware is shown in Figure 22 (at top).

The rear panel should now be flush with the back edge of the

PC board. If not, one of the connectors may not be properly installed.

Solder J3's leads to the board. These connections are critical to

reliable operation. The solder should coat J3's pads on both sides of the board, and the joints should be clean and shiny.

Trim J3's leads on the bottom of the board.

Page 31

Solder the red fan wire to the pad labeled "FAN+" (near J6).

Solder the black fan wire to the "FAN-" pad.

Top

Route the fan wires away from RFC1.

Solder J2's wires to the points indicated in Detail A2 of Figure 22. The red wire goes to T4 pin 5, black wire to the pad labeled "GND" near E1, and bare wire jumper to T4 pin 6.

Locate a large 100-µH RF choke ("101") for use at RFC10 (0.75" lead spacing). Position the RF choke as close as possible to the rear panel as shown in Figure 23. Solder RFC10 to the center pin of J2 and the grounded solder lug using short leads.

RFC10

101

Figure 23

Examine the area around J2 closely to make sure that none of the wires running to the center pin are contacting nearby hardware.

Locate the smaller binocular coil form for use at T1. As shown in the side view, Figure 24a, the ferrite core is offset upward slightly, leaving a gap at the bottom. The end view, Figure 24b, identifies contacts 1 and 3. The other end is contact 2.

(a)

(c)

(b)

1 3

Figure 24

Place T1 at its indicated location, with the gap (bottom side) toward the PC board. Contacts 1, 2, and 3 must be aligned with their PCB pads. Figure 24c shows all of T1's pads (1-5).

T1 is very difficult to remove once installed. While

soldering, make sure it is centered directly over its component outline and is seated flat against the board. T1 may be just slightly larger or smaller than the indicated outline.

Using a heavy solder iron (pencil or gun), solder only contact 1 of T1 to the board. Solder over the full length of the contact.

If T1 is not centered, reheat contact 1 and adjust its position.

Solder contacts 2 and 3. Solder along the full length of each contact.

Page 32

There are two sizes of Teflon wire (gray): #18 (larger) and #22 (smaller). The smaller size will be used at T1, and the larger at T2. Cut a 9" (23 cm) length of the #22 Teflon wire.

Remove 1/4" (6 mm) of insulation from one end, then twist the strands together. Tin the strands using a small amount of solder.

Solder the Teflon wire to the pad labeled T1-4.

Thread the wire through the core (1 turn) as shown in Figure 25a. You'll then have one loop of wire on the left side of the core.

Add a second turn by passing the free end of the wire back through both holes in the core, as you did in (a). Pull on the wire so that the winding is tight. The winding should then look like Figure 25b, with two loops on the left side.

Add a third turn, again passing the free end back through both holes in the core (Figure 25c). Pull the wire to tighten the winding.

Count the loops on the left side to make sure you now have exactly three. There will be two loops on the right side, plus the two ends of the wire.

Cut the free end of the wire to a length of 5/8" (16 mm), measured from where it exits the core. Remove 1/4" (6 mm) of insulation, then tin and twist the leads.

(a)

(b)

Solder the wire to the pad labeled T1-5.

(c)

Figure 25

Page 33

Locate the larger binocular coil form for use at T2. Note: T2 may vary in length from 1" to 1 1/8" (25 to 29 mm). The given pads can accommodate either length. Figure 26 shows all five of T2's pads.

Cut an 18" (46 cm) length of #18 Teflon wire (gray). Remove

1/4" (6 mm) of insulation from one end, then twist and tin the strands.

Solder the Teflon wire to the pad labeled T2-5.

Thread the wire through the core (1 turn) as shown in Figure 27a.

Figure 26

Center T2 at its indicated location with the gap (bottom side) toward the board. Contacts 1-3 must be aligned with their PCB pads.

Once T2 is installed, it is nearly impossible to remove.

While soldering T2, make sure it is centered directly over its component outline and is seated flat against the board.

Using a heavy solder iron, solder contact 1 to its pad over just a small portion of its length.

Add a second turn, pulling the wire so that the winding is tight.

The winding should look like Figure 27b (2 loops on the right).

Add two more turns (c), (d). Pull the wire to tighten the winding.

There should now be exactly four loops on the right side.

Cut the free end of the wire to a length of 1 1/4" (32 mm), measured from where it exits the core. Remove 1/4" (6 mm) of insulation, then tin and twist the strands. Solder the wire to T2-4.

(a) (b)

5 5

If T2 is not centered over its component outline, or is tilted,

reheat contact 1 and adjust T2's position.

Solder contact 3 over its full length.

Solder contact 2 over its full length. Keep the iron tip away from

nearby components, especially potentiometers R26 and R27.

Solder contact 1 over its full length.

Figure 27

Page 34

Install the following resistors near T1. Note: Three sizes of 10ohm resistors are to be installed, one rated at 1/4 watt, one rated at 1 watt, and three rated at 2 watts. Compare the sizes ahead of time.

__ R9, 10 ohms, 5%, 1/4 W (brown-black-black) __ R34 and __ R35, 10 ohms, 2 W __ R19 and __ R20, 3.6 ohms, 2 W __ R23, 10 ohms, 1 W (brown-black-black) __ R22, 100 ohms, 3 W __ R21, 10 ohms, 2 W (form leads to fit given pad spacing)

Install relay K3, located near T2.

Install the following capacitors in the low-pass filter area:

__ C2E, 1000 pF, 500 V silver mica __ C2A, and __ C6D, 1200 pF, 500 V silver mica __ C2C, 2200 pF, 500 V silver mica

Install the following capacitors, located in the area between the two power transistors.

__ C58 and __ C59, 0.1 µF (104), 0.2" lead spacing __ C80 and __ C81, 4700 pF (472), 0.25" lead spacing

Page 35

Unwrap the heat sink and place it on a soft, clean surface to protect the finish. Orient it with the speaker hole at top left and fins facing down (Figure 28). The raised area on the right side is the pedestal, where the power transistors will be mounted. The PC board will be mounted at the seven points marked H and S.

The heat sink has a non-conductive, black anodized

finish. To ensure good electrical contact between the heat sink and PC board, the finish will be removed at the seven points shown at right. When working with the heat sink, be careful not to nick or scratch the fins (on the opposite side).

Attach a portion of the supplied sandpaper (no more than 1/4th of the sheet) to a flat piece of wood or a sanding block. The block should be at least 4" long and 1" wide (10 x 2.5 cm).

Locate the two machined standoffs on the pedestal, labeled S in Figure 28. Lay the sanding block across the top surfaces of both standoffs. Keeping the block parallel to the pedestal at all times, carefully sand off just enough of the black finish to expose the top surfaces of the standoffs. Do not remove any further material,

since this may affect proper spacing of the power transistors.

Use the sandpaper (but not the sanding block) to remove the finish around the holes labeled H in Figure 28. The area of finish removed should be approximately centered over each hole, and at least 1/4" (6 mm) in diameter. Note: You can also scrape away the anodization with a sharp tool or a hand mill (Dremel tool) with a wirebrush attachment. Be careful not to cut down into the aluminum.

Locate the 7 set screws (4-40 x 1/2") and the small hex wrench. Thread a set screw into each hole marked H or S, being very careful not to cross or strip the threads during insertion. Tighten the set screws using the hex wrench.

Pedestal

Figure 28

The leads of some components near the power

transistors must be flush-trimmed as explained in the next step. This will prevent leads from shorting to the pedestal.

Flush-trim the leads of the components listed below on the

bottom of the board. The leads must be less than 1/32" (0.7 mm) long.

__ C40 __ C50 __ C80 __ C81 __ C58 __ C59 __ L18 __ C31 __ Z1 __ L16

Thread 3/16" dia., 3/16" long standoffs onto the five set screws marked H. Do not use lock washers. Tighten the standoffs using pliers, but do not over-tighten.

Using your DMM's lowest resistance scale, check for continuity (< 1 ohm) between one set screw and all of the others.

Over the rest of the board, trim any component leads that you may have missed earlier, including connector leads. Use a ruler to make sure that all leads are trimmed to less than 1/8" (3 mm).

Page 36

The PC board will be attached to the heat sink

temporarily in the next step. This will position the power transistors correctly for soldering. Do not install thermal pads at this time.

Place the KPA100 PC board assembly on top of the heat sink. Secure the board to the heat sink at the pedestal set screws using 1/2" (12.5 mm) long standoffs. Thread them on hand-tight only.

Locate the two flange-mount power transistors. If the tabs are bent, straighten them carefully using long-nose pliers.

Pre-tin the tabs of Q1/Q2 (top and bottom) with a small amount of solder. Also pre-tin the pads for Q1 and Q2 on the PC board. A

high-wattage iron will be required to tin the emitter pads.

Place power transistors at Q1 and Q2, orienting the four tabs as shown in Figure 29a. The notched tab must be aligned with the

PCB pad labeled "C" (collector).

Use an iron with a large tip when soldering the

emitters of Q1 and Q2. A small tip cannot supply enough heat.

Solder all four tabs of Q1 and Q2 to their pads. The solder should

coat the entire tab and the PC board pad surrounding it (Figure 29b).

Remove the screws from Q1 and Q2.

Remove the standoffs holding the PC board to the heat sink, then

remove the board.

Wrap the heat sink back up and set it aside.

Install 68-ohm, 2-watt resistors at R38 and R39. These resistors straddle the adjacent emitter leads of Q1 and Q2. Form the leads to match the pad spacing, and keep the resistors spaced slightly apart.

Solder R38 and R39, then flush-trim the leads.

Locate a 1200-pF silver mica capacitor (C83). Trim the leads to exactly 1/8" (3 mm) long.

(a)

(b)

C B

Figure 29

Secure Q1 and Q2 to the pedestal temporarily using four 4-40 x

1/4" (6 mm) pan head screws and four split lock washers. The lock

washers must be used, or the screws may bottom out.

Place C83 in exactly the position shown in Figure 30, near the "R38" and "R39" labels. Solder C83 to the tops of the indicated

pads. Do not insert the leads into the holes.

R39

R38

(a)

Figure 30

(b)

Page 37

Figure 32 (page 38) shows wiring details for J1, J4, and J5.

Refer to this illustration while completing the following steps.

As shown in Figure 32, two types of 2-pin connector housings are supplied: 0.156" pin spacing for use at J1 and J4, and 0.1" spacing for J5. Also supplied are small and large crimp terminals (see parts list photos). Locate the smaller of the housings and two of the small crimp terminals for use at J5.

Cut a 4.5" (11.5 cm) length of RG-174 coaxial cable. Using a sharp tool, remove about 3/4" (2 cm) of the coax jacket from each end (see Figure 31). Be careful not to nick the braid.

Figure 31

Cut a 6" (15 cm) length of two-conductor speaker cable (small gauge, with clear insulation). Split the conductors at both ends, then remove 1/4" (6 mm) of insulation from all four wires. Avoid nicking

or tearing the wire strands when removing the insulation.

Twist each wire's strands together, then tin the wires, using a very small amount of solder (just enough to hold the strands together).

Attach crimp terminals to the two wires at one end as shown in Figure 32 (Detail A). Before soldering, fold the small flaps of the terminal closed using long-nose pliers. This will hold the wire in place.

When you insert crimp terminals into the housing in the next step, they should snap into place. Each terminal has a small retaining tab on the back that latches into a hole in the housing. The location of the retainer and its hole in the housing are shown in Detail B.

Figure 32 shows J5 with the wires attached, and the small guides on the connector facing down and away from you. Hold the connector in this orientation, then insert the silver wire into the right hole of the housing until it snaps into place. Insert the copper wire into the left hole. Verify that the retainer tab is locked in place (Detail B).

Insert the wires at the other end of this cable into the pads labeled AF (silver wire) and GND (copper wire) on the KPA100 board. Insert the wires all the way up to the insulation to avoid leaving any exposed lead length. Solder both wires.

Locate the two larger 2-pin housings and four of the large crimp pins for use at J1 and J4.

Separate the braid (shield) from the center conductor at both ends. Clip off about half the strands of the braid close to the jacket, then twist the remaining braid into a thin bundle.

Remove a small amount of insulation from the center conductor. Use long-nose pliers to hold the center conductor while stripping it.

Solder the center conductor and shield to crimp terminals.

Insert the terminals into a 2-pin housing as shown in Figure 32 (center conductor on the left, braid on the right).

Solder the other end of the coax cable to the two pads labeled "RF IN" and "GND" on the KPA100 board (near relay K1). The shield

goes to "GND".

Cut two 4.5" (11.5 cm) lengths of #20 AWG stranded insulated hookup wire, one red and one black. Remove 1/4" of insulation from each end of both wires.

Twist the strands together tightly, then tin the wires. Use a very

small amount of solder.

Solder one end of each wire to a large crimp terminal.

Insert the terminals into a large 2-pin housing as shown in Figure 32 (black wire on the left, red wire on the right).

Solder the free end of the red wire to the pad labeled "12K2" on the KPA100 board. Solder the black wire to the nearby "GND" pad.

Use two cable ties to secure the wires at the indicated locations.

Page 38

J1, RF

Downloaded by

RadioAmateur.EU

(0.156")

4.5" (11.5 cm)

SHIELD

4.5" (11.5 cm)

RF IN GND

GND

12 K2

FAN

J4, 12V

(0.156")

RETAINER

RED

6" (15 cm)

J5, AF

(0.1")

GND AF

Ribbon Cable To Control Board, P4

SILVER

Figure 32

2.5" (6.4 cm)

SPKR

SPEAKER

GND

Page 39

The 12V and RF cables to the K2 use identical connectors. In the next section, a capacitor will be added to the RF board to prevent damage to components in the event that the cables are reversed. In addition to this, you should mark the 12 V connectors (KPA100-J4 and RF-P3) in some way to distinguish them from the RF connectors.

Unwrap the heat sink and place it on a soft, clean surface.

Using sand paper, remove the heat sink's black finish at the four

areas shown in white in Figure 33. At point A, be very careful to

sand only on the narrow shelf, not on the tops of the fins.

Cut a 3" (7.5 cm) length of the 2-conductor speaker wire.

Split the conductors out at each end. Remove 1/4" (6 mm) of insulation from all four wires, then twist and tin the strands using a small amount of solder.

Near the speaker cutout on the KPA100 board you'll find two pads labeled "SPKR" and "GND". Solder the silver-colored wire to the pad labeled "SPKR", and the copper wire to "GND".

Trim the grille cloth so that it is the same size as the speaker

frame.

Place fibre washers (black) on each of the heat sink's four speaker mounting holes. Cut just enough material off each corner of the grille cloth so that it fits between the washers, not touching them.

Place the speaker on top of the grille cloth and fibre washers (Figure 34). Align the speaker frame with the front and side edges of the heat sink. The speaker terminals should face the front, as

shown in Figure 32.

Secure the speaker using 4-40 x 3/16" (4.8 m) black, flat head screws (Figure 34.) Do not use lock washers.

Figure 33

Figure 34

At this point you should have no unfilled component locations.

Page 40

Locate the two TO-126 thermal pads (rectangular, gray). Remove the adhesive backing, then attach them to the heat sink pedestal (adhesive side down) at the locations marked Q3 and Q4 in Figure 35. Center each pad over its associated hole.

Install the PC board/rear panel assembly onto the heat sink. Press the board down until it is flat against all seven standoffs on the heat sink, including the two machined standoffs on the pedestal.

Secure the rear panel to the heat sink using three 4-40 x 3/16" (4.8 mm) black pan head screws.

Figure 35

Locate the thermal pads for Q1 and Q2. Remove the small punch-outs at the mounting holes in each pad, if still present. Note: these thermal pads do not have adhesive backing.

Place thermal pads at Q1 and Q2 as shown above. Align the holes in the pads with the holes in the heat sink. Do not omit these pads:

the power transistors will be quickly destroyed without them.

Do not use lock washers between the heat sink and the

PC board when attaching the board in the next step.

Adjust the locations of the thermal pads for Q1 and Q2, if

necessary, so that they are still aligned with the mounting holes.

Secure Q1 and Q2 to the heat sink using 4-40 x 1/4" (6 mm) pan

head screws and split lock washers. Use a small-handled Phillips

screw driver to fasten the hardware tightly without risk of over-tightening or stripping out the screw heads.

Secure Q3 and Q4 to the heat sink using 4-40 x 1/4" (6 mm) pan head screws and split lock washers. Use a small-handled driver as you did with Q1 and Q2.

Look between the PC board and heat sink to verify that no component leads or bottom-mounted components are touching the heat sink or associated hardware.

Place a #4 split lock washer over each of the seven set screws.

Install 1/2" (12.5 mm) standoffs on the two set screws at the front edge of the board. One is near the "SPKR" and "GND" pads, and the other is near the "AF" and "GND" pads. Do not overtighten.

Install 5/8" (16 mm) standoffs on the remaining five set screws.

Unwrap the top cover panel. If masking tape (usually green in color) is present on the inside surface, you'll need to remove it. Use a ball-point pen to push on the tape through each hole until the tape lifts away. Then peel the tape off, using a sharp tool if necessary. Be careful not to scratch the outside surface of the panel.

Install the top cover panel onto the narrow shelf at the front of the heat sink. Secure the panel using three 4-40 x 3/16" (4.8 mm) black pan head screws.

Solder the speaker wires to the speaker. The silver wire should be soldered to the speaker's (+) terminal.

Page 41

Alignment and Installation

You will need two power supplies to complete testing of

the KPA100: the low-current supply that you use with your K2 at the 10-watt level (3 amps minimum), and a 20-amp, 13.8 V supply for high power use. The instructions will specify when to connect each power supply.

Make the resistance measurements listed below, touching the DMM's (+) lead to the indicated points, and the (-) lead to ground. Note: The reading from J3 to ground may initially read a short (0 ohms) because of the large electrolytic capacitor on the 12 V line. Use a low resistance range, and wait up to 20 seconds for the reading to stabilize.

KPA100 Test Points (+) Resistance

J3 + lead (red) (see note above) > 10 k

Q1 collector > 10 k Q2 collector > 10 k

Q1 base 12-16 ohms Q2 base 12-16 ohms

J2 (antenna jack) center pin 0-2 ohms

Q9 tab (near rear panel) > 10 k

D13 cathode (banded end) > 10 k

Closely examine all of the cables on the left side of the KPA100. Make sure the crimp terminals are properly seated, and that there are no loose wire strands that might cause a short.

RED

SOLDER

BLACK

Figure 36

Use only the supplied 12 AWG, 2-conductor stranded

wire (red/black) for the DC power cable.

Separate the two conductors at one end of the 12 AWG, 2conductor cable. Remove 5/16" (8 mm) of insulation from the red and black wires at one end. Do not nick or cut off any of the strands.

Do not crimp the 30-amp terminals. They will be

soldered in the next step, providing a reliable connection.

Insert the wires into 30-amp terminals as shown above. Solder the wires to the crimp terminals, using enough solder to completely surround the wire and fill the interior of the terminal. (This may take as long as 10 seconds if you're using a small iron.) Be careful not to get solder on the thin tongue that extends from the front of the terminal.

Locate two DC input connector housings, one red and one black. Hold the two connectors in the orientation shown in Figure 36. Look closely at the sides of the connectors. Each has a small tongue on the right side, and a groove on the left.

Slide the tongue on the right side of the red housing into the groove on the left side of the black housing. Make sure the housings are mated exactly as shown, with the black housing to the right and the "hoods" at the front of the connectors facing up. The interlocking tongue and groove must be fully meshed.

Insert the terminals into the housings exactly as shown in Figure

36. The terminals should snap securely into place. Pull on the wires individually and make sure that they cannot be pulled out (if so, the terminals are probably inserted upside down).

Optional: The supplied spring pin may be used to keep the red and black housings from slipping apart (see above). The manufacturer of the connectors recommends gluing the pin in place with super-glue.

Page 42

You should install the supplied fuse holder even if your

20-amp power supply has its own fuse or circuit breaker. This will allow you to use the K2/100 transceiver with an unfused power supply or battery if the need arises.

Insert the 8" (20 cm) red wire through a fuse holder half. Remove

5/16" (8 mm) of insulation, then solder the wire to a fuse terminal (c).

Pull the terminals back inside the holder halves, and install the

supplied fuse (c). Press the two halves together and twist to secure.

At the far end of the DC power cable, clip the red wire at the

point shown (Figure 37a). Peel away and save the short red wire.

(a)

8" (20 cm)

(b)

(c)

Figure 37

Peel the attached red wire back 3" (8 cm). Remove 5/16" (8 mm)

of insulation from the end (Figure 37a).

Prepare the free end of the cable as needed to match your 20-amp

power supply connections.

At the far right edge of the K2 RF board are connectors P6 (Aux RF) and P3 (Aux 12V). If you have not previously installed the KAT2 and KBT2 options, you'll need to install the supplied 2-pin,

0.156" spacing male connectors as described below. A DC blocking capacitor (RF-Crf) has also been supplied, which can protect against damage due to accidental swapping of the RF and 12V cables.

If the 160-meter option is present, remove its one screw and

unplug it. Leave it (and the RX ANT jack) attached to the heat sink.

Remove the K2's bottom cover (6 screws).

Remove the K2's heat sink/lower rear panel (6 screws, two 4-40 nuts, and the nuts on the antenna and key jacks). Save the thermal pads for Q7 and Q8, which may fall off when the heat sink is removed.

Install 2-pin male connector at P6 and P3 as indicated by their outlines. They must be oriented so that their plastic polarizing tabs are toward the front panel of the K2. Solder P6 and P3.

Optional (recommended): Install the supplied DC blocking cap (RF-Crf, .047 µF) on the bottom of the RF board at the location shown in Figure 38 (page 43). The indicated trace must be fully cut; verify that it is open the lowest resistance scale of your DMM.

Insert the attached red wire through a fuse holder half, as well as the spring (b). Note: If the wire won't fit into the fuse holder or spring, you may need to peel off the thin, clear sleeve over the insulation. To remove the sleeve, slit it lengthwise with a sharp tool, with the blade inserted between the sleeve and the insulation. Be careful not to cut into the insulation itself.

Solder the red wire to a fuse terminal.

Carefully examine all hardware associated with the PA transistors, Q7 and Q8, on the bottom of the RF board. If any of the plastic hardware or the thermal pads appears to be melted or damaged, you should order the K2 PA Hardware Kit from Elecraft.

Re-install the heat sink/lower panel and any new Q7/Q8 hardware as described in Part III of the basic K2 assembly instructions. Do not

over-tighten any of the hardware.

Page 43

Using a DMM on its lowest resistance scale, measure resistance

from the collectors of Q7 and Q8 to ground. If you see a reading of less than 100 Ω, the heat sink may be shorted to one of the transistor tabs. Remove the heat sink and correct the short before proceeding.

Re-install and secure the 160-meter module if applicable.

Re-install the K2's bottom cover.

Crf

Set the KPA100 upside down to the right of the K2 on a suitable

platform, as you did earlier.

Connect a low-current (3 amp minimum) power supply to the

K2's DC barrel jack (RF-J3).

Plug in the ribbon between the KPA100 and the K2 Control

board.

Turn on the K2. You should see the N O P A P S message as

before, since no power supply is connected at KPA100-J3.

Check the K2 current drain and voltage using the DISPLAY switch. Current should be about 100-200 ma higher than without the KPA100.

Set your DMM for DC volts, 200 or 300 V full scale (or auto ranging). Connect the DMM's (-) probe to the ground jumper on the KPA100 board (near U1). Using the DMM's (+) probe, make the voltage measurements listed below.

KPA100 Test Point (+) Voltage

D13 cathode (banded end) 90 to 150 V

U4 (MAX1406) pin 8 -5 to -25 V

TP1 (near Q2 and T2) 0 to 0.1 V

J3 + lead (red) 0 V

Cut

K10

Figure 38

Install the black rubber BNC connector cap on the K2's BNC

antenna jack. The BNC antenna jack will not be used when

the KPA100 is installed. The antenna will be connected to the KPA100's SO239 jack instead, even when using low power.

If you have any difficulty during the test or alignment steps that follow, refer to the Troubleshooting and Repair section of this appendix.

RS232 Port Test

If you already have a serial I/O cable assembled for connecting your K2 to a PC, and have made any needed Control board modifications, you can test the RS232 interface at this time. Otherwise, you can complete alignment and installation and

Page 44

Receiver Tests

SWR Bridge Null Adjustment (C1)

Plug a pair of headphones into the K2's headphone jack. Turn on

the K2 and adjust the AF GAIN control so that noise can be heard.

Plug the audio cable from the KPA100 (J5) into the K2's internal speaker jack (RF-P5). If this has any effect on the noise heard in the headphones, you may have a short in the wiring of J5.

Unplug the headphones. You should now hear noise coming from the KPA100's speaker. The sound may be reduced in volume (it will sound normal when the KPA100 is installed inside the K2). If the signal sounds distorted or very weak, check the wiring of the J5.

Plug the headphones (or a speaker) into the external speaker jack at the back of the KPA100 (J6). You should hear the same signal as before, and louder if you're using headphones. Note: If you're using stereo headphones, you'll only hear the signal in one ear.

Turn the K2 off.

Connect the KPA100's internal RF cable (J1) to the K2, at RF-

P6 (labeled "AUX RF"). Do not plug J1 into RF-P3 ("AUX 12V").

Note: Do not connect the KPA100's internal 12VDC cable (J4) to the

K2 at this time.

Turn the K2 on.

Connect a 50-ohm dummy load rated at 5 watts or higher to the

KPA100's SO239 antenna jack (J2).

Select the 40 meter band (7000-7300 kHz). Set the K2's POWER

control for about 5 watts.

Turn the FWD and REFL potentiometers on the KPA100 (R26

and R27) to about their midpoints.

Set the SWR null trimmer (KPA100-C1, near the antenna jack)

so that its adjustment slot is perpendicular to the KPA100 rear panel.

Note: With the KPA100 installed, the TUNE mode display includes both forward power and SWR. For example, 5 . 0 1 . 0 - 1 m e a n s

5.0 watts, output, and an SWR of 1.0:1.

Locate a small insulated-handle screwdriver or tuning tool, and

prepare to adjust C1 on the KPA100. Enter TUNE mode by holding

T U N E . Adjust C1 for an SWR indication of 1 . 0 - 1 on the K2 LCD.

Cancel TUNE mode by tapping or holding T U N E again.

Note: You'll see an indication of 1.0-1 over a small range of C1's rotation. Position C1 at approximately the middle of this range, repeating the TUNE adjustment several times if necessary.

Optional SWR fine adjustment

Connect an antenna to the KPA100's SO239 antenna jack (J2). Verify that you hear signals or atmospheric noise on all bands. You should hear relays switching on the KPA100 as you change bands.

Note: The low-pass filter relays on the KPA100 will switch at different bands than those on the K2 RF board. On the KPA100, 30/40, 17/20, and 10/12/15 meters each share a single low-pass filter.

The signal from the KPA100's 4-MHz crystal oscillator (X2) may be audible at the high end of the 80-meter band. If this is the case, you can move it to a point just above 4 MHz using trimmer C27. The signal from the 4-MHz oscillator on the K2 Control board may be much stronger. Rotate C27 slightly to identify the KPA100 signal.

You may be able to adjust C1 more accurately by measuring the reflected voltage directly using a DMM or an analog voltmeter. Connect the (-) lead to the ground jumper on the KPA100 board (near U1). Touch the (+) lead to pin 1 of KPA100-U5 (LM358). Repeat the TUNE procedure from above, adjusting C1 for a reading as close as possible to zero volts on the voltmeter.

Page 45

Power Calibration (R26 and R27)

KPA100 Power Supply Test

Connect an external wattmeter between the KPA100 antenna

jack (J2) and the 50-ohm dummy load.

Select the 40 meter band (7000-7300 kHz). Set the POWER

control for 5.0 watts.

Note: This calibration step can be done later at a higher power level if your wattmeter doesn't have an accurate low-power scale.

Locate a small flat-blade screwdriver and prepare to adjust R26 on the KPA100. Enter TUNE mode on the K2. Adjust R26 for a power indication on the K2 LCD that matches the reading of the external wattmeter. Cancel TUNE mode. Repeat as needed until the K2's LCD shows the same power level as the external wattmeter.

Set R27 to exactly the same position as R26 (visually). This will provide adequate accuracy for SWR readings.

Check the SWR in TUNE mode on every band. The SWR should be close to 1.0 to 1 on all bands (1 . 0 - 1 ).

Temperature Calibration (CAL tPA)

Turn the KPA100 bias control, R6, fully counter-clockwise.

Tap M E N U to enter the K2 menu, then scroll to the C A L menu entry. Hold E D I T to highlight the CAL parameter. Select C A L t P A

(KPA100 temperature calibration). Then hold E D I T again to activate the C A L t P A function.

Using the VFO knob, adjust the temperature shown on the LCD to match the room temperature in degrees C (Celsius). To convert Fahrenheit to Celsius, subtract 32, then multiply the result by 0.55.

Tap or hold M E N U to exit C A L t P A .

In following tests, you'll connect both your low-current and highcurrent power supplies to the K2 in different combinations. This will test the K2's dual-supply capability, which is useful for emergencypower situations. For example, if a 12 volt battery is kept floatcharged and connected to the K2's low-current DC input jack, the transceiver can be operated at the 10- to 15-watt level even if the power mains go down or the high-current supply fails.

Do not key the transmitter during these tests.

Turn the K2 off. Disconnect the low-current power supply.

Make sure your high-current power supply is turned off.

Connect the high-current supply (20 A) to KPA100-J3.

Connect the KPA100's internal K2 DC cable (KPA100-J4) to the

K2's Aux 12V input (K2-P3, on the RF board).

Rotate the K2's POWER control fully counter-clockwise.

Turn your high-current supply on. The K2 should remain off.

Check your high-current supply's voltage and current drain, if it has built-in metering. The voltage should be the same as its no-load voltage (nominally 13.8V). The current should be nearly zero.

Turn on the K2. You should not see a N O P A P S message, since you do have a power supply connected to the KPA100.

Check the K2's voltage and current using the D I S P L A Y switch. The voltage indicated should be the same as the high-current power

supply's voltage, less about 0.3 to 0.5 volts (the voltage drop across diode KPA100-D9). The current should be about 100-200 mA higher than with the KPA100 removed.

Tap M E N U , then tap D I S P L A Y to access the secondary menu. Scroll to the P A menu entry, then hold E D I T and change the

parameter to O F F . Exit the menu.

Page 46

Verify that the POWER control range is 0.1-15 watts.

External Amplifier Keying Test (PA KEY)

Use the menu to set the P A parameter to O N . Exit the menu.

Verify that POWER can now be set in 0.5-watt increments up to

10.0 watts, and 1-watt increments from 11 to about 110 watts. Below 11 watts, the KPA100 will be in "bypass" mode. You should hear the bypass relays on the KPA100 (K1 and K2) switch at this point.

Turn the K2 off. Also turn off your high-current power supply.

Leaving the high-current power supply connected, but turned off, connect the low-current power supply to the K2's normal DC input jack (barrel connector, RF-J3).

Turn the K2 ON. After E L E C R A F T is shown on the LCD, you should see the message N O P A P S . POWER range will be 0.1-15 W.

Turn the high-current power supply on. You should see P A P S O N . POWER range should again be 0.1 to 110 watts.

Turn the high-current power supply off. After 1 to 10 seconds, should see N O P A P S . The delay depends on how long it takes for the high-current power supply to drop to about 8 volts.

Turn the high-current supply back on.

Turn off and disconnect the low-current power supply. It should not be used during the remaining tests.

Fan Test

Use the MODE switch to select CW mode (mode letter changes to C). Enter CW TEST mode by holding V O X . The letter C should now be flashing. In this mode, the K2 will not put out any power when you key the rig either with a key or with the TUNE switch.

Set your DMM to its lowest resistance scale. Connect the (-) probe to ground, and touch the (+) probe to the tab of Q9 on the KPA100 board (or to the center conductor of the PA KEY output jack, J7).

The DMM should be indicating a high resistance (typically indicated by a flashing display). Hold T U N E on the K2 to key the transmitter. The resistance reading should drop to less than 3 ohms.

Tap any switch to exit TUNE mode. Exit CW test mode by holding V O X . The mode letter will stop flashing.

Bias Current Adjustment

This is the most important KPA100 alignment step. If

your 20-amp power supply does not have accurate current measurement capability in the 0-1 amp range, you'll need a DC milliammeter to set the bias current. Most DMMs have a suitable high-current range. A full-scale range of about 1 amp (1000 mA) or higher is required, with resolution of 0.02 amps (20 mA) or better.

Turn the K2 off.

Enter the PA menu entry and edit the parameter. Tap D I S P L A Y

until you see F A N n o r (normal). The fan should not be running. (The purpose of the various fan modes will described later.)

Tap D I S P L A Y again to set the fan mode to F A N L o H i . The fan

should switch to low speed, which should be barely audible.

Tap D I S P L A Y to set the fan mode to F A N H i . The fan should switch to high speed. Tap D I S P L A Y again to return to F A N n o r . Exit the menu.

Turn the high-current power supply off.

As a precaution, connect a dummy load (any power rating) to the KPA100's antenna jack (J2). This will protect the transmitter in the event that bias is set too high or the transmitter is keyed.

Rotate R6 on the KPA100 (Bias Set) fully counter-clockwise.

Page 47

If you're using a DMM to make the current measurements, set it

to a 1 amp or higher range. Your DMM may have a separate high-

current tip jack. Consult the DMM's manual before using it.

The DMM must be inserted in series with the positive lead

of the DC power cable. Connect the (+) lead of the DMM to the power supply side of the circuit, and the (-) lead to the KPA100 side.

Transmit Tests

Connect a 100 watt dummy load to the KPA100 antenna jack

(J2). Avoid using an antenna for initial transmit tests.

Make sure the high-current power supply is connected to the

KPA100 and is turned on.

Turn on the high-current power supply, then turn on the K2. Using the menu (secondary), make sure that the P A menu entry is set to O N . Exit the menu.

Use the MODE switch to select CW mode (mode letter changes to C ). Enter CW TEST mode using V O X (the letter C should flash).

Rotate the POWER control on the K2 through its full range (0.1110 watts), then set it to 0.1 watts (fully counter-clockwise). The DMM (or other current meter) should show about 200-400 mA, depending on how you have the K2 configured.

Set the POWER control for 11 watts. The current should increase by about 200 mA (150 mA for the KPA100 T-R switch, and 50 mA for the fan, running at low speed). Record this current: ________ mA. Add 400 mA (200 mA per power transistor) to this to determine the target reading for the bias-setting step below: _______ mA.

Prepare to adjust R6 on the KPA100 (Bias Set). Make sure you're in CW TEST mode (mode letter C flashing).

Enter TUNE mode, then adjust R6 clockwise until the current meter shows approximately the target current recorded above. The current may slowly drift higher, but R6 should be left at a setting that provides the target current when you first enter TUNE mode.

Exit TUNE mode by holding any switch.

Turn the K2 off, then turn off the high-current power supply.

Turn the K2 on. If you're using an antenna, switch to the band it

is resonant on, and locate an unused frequency.

Set the POWER control for about 5 watts. The KPA100 will be

in bypass mode (disabled). Select the 40-meter band.

Enter TUNE mode for a few seconds (maximum) and make sure

that the K2 (and external wattmeter, if any) indicates about 5 watts.

Select CW mode using the M O D E switch. Using another ham-band

receiver or transceiver, listen to your signal while sending CW.

Set the POWER control for 20 watts. You should hear the relays

on the KPA100 switch into high-power mode at the 11-watt point.

Enter TUNE mode for a few seconds (maximum) and make sure that power output is about 20 watts. Note: The power may rise gradually to a few watts above the intended level, the drop back slightly below it. This is normal ALC behavior, and may happen more than once as the power transistor bias stabilizes during key-down.

Listen to the signal quality in the second receiver while keying. The 20-watt signal should be stronger than the 5-watt signal, but the quality of the keying and sound of the signal should be identical.

To protect the power transistors from high SWR, TUNE

mode initially limits power to 20 watts. To override, hold T U N E and

D I S P L A Y together, or turn the POWER knob after TUNE starts.

Disconnect the DMM and any clip leads you used for current measurement. If you moved your DMM's (+) lead to a different tipjack on the meter for high-current measurement, return it to the normal (+) jack.

Test the KPA100 at your dummy load's rated power, up to 100 watts. Limit key-down time to a few seconds. Note: If you're using an antenna, and the SWR is too high for a given power level, the K2/100 will automatically reduce power. You'll see H I R E F L on the LCD.

Page 48

RF amplifiers are most efficient at one power level;

efficiency decreases above or below this point. For example, at 50 W, the current may be 70-80% of the current at 100 W.

Installation

Turn off the K2.

Key-down current drain is typically 12-18 amps at 100 watts, depending on the band. You can confirm this easily if your power supply has current metering. An alternative is to measure the DC voltage across the current-sensing resistor, R7. Every 5 millivolts of voltage across R7 equals one amp of Q1+Q2 collector current.

Optional: If you want to re-do power calibration (R26/R27) at a higher power level, do so now. 50 watts is a good choice, assuming your dummy load is rated this high.

Check output capability, signal quality, and current drain on the remaining bands. This is necessary to ensure that all five low-pass filters are functioning correctly.

SSB Mode Transmit Tests (Requires KSB2 Option)

Switch to USB or LSB mode. Connect a microphone to the K2.

Set the compression level (SSBC) to 1-1 using the menu. This turns off speech compression, allowing you to better hear your voice quality in the next step.

Using headphones with the monitor receiver, listen carefully to your SSB signal at both 5 watts and 20 watts. If the signal quality is good in both cases, with no sign of distortion, try higher power levels (up to 100 watts or the rated power of your dummy load).

Before you go "live" in SSB mode, you should make sure

that you've properly aligned your K2/100 transceiver's filters for USB and LSB transmit. SSB transmit filter alignment (that is,

adjustment of the BFO settings for FL1) can be done by listening critically in a monitor receiver, or with the help of a station nearby, or by using a computer spectral analysis program. Refer to the KSB2 manual for basic alignment information. On our web site, you'll find more detailed application notes.

We recommend disconnecting the K2's internal frequency counter cable. Leaving this cable connected may cause a slight increase in the amplitude of spurious signals on some bands.

Verify that the two standoffs at the front edge of the KPA100 board are 1/2" (12.7 mm) tall. The others should be 5/8" (16.9 mm).

Make sure that the 4-MHz crystal, X2, does not have any solder on the top of the can. If the ground wire was installed on the top, it must be moved to the side of the can, and all solder removed from the top using desoldering braid. Otherwise the shield will not fit correctly.

Place the shield on the KPA100 assembly. If the shield doesn't

lay flat against all seven standoffs, it may need to be straightened.

Secure the shield to the standoffs using split lock washers and

4-40 x 1/4" (6 mm) pan head screws.

Turn the KPA100 assembly over carefully and install it in the K2. Make sure none of the cables become pinched. (After the KPA100 is installed, you can remove the right side panel to get a better look at cables, although this should not be necessary.)

Secure the KPA100 to the K2 using six 4-40 x 3/16" black pan head screws (see Figure 8, page 20). Note: There are no individual holes in the heat sink for the side panel screws. Instead, they thread into the thin channels that run the length of the heat sink.

If you plan to use the KPA100's RS232 port for remote control of the transceiver, follow the instructions starting on page 51.

Read the next section before putting your K2/100 on the air.

IMPORTANT: The hardware holding the RF power transistors in place will loosen slightly during initial use. After 5-10 hours of normal operation at 50 watts or more, remove the KPA100 assembly and its shield, then re-tighten the hardware approximately 1/8 turn.

Page 49

Using the K2/100 at High Power

Antenna

Power Supply

Dual-Supply Capability

There are two DC input jacks on the K2/100: a low-current DC barrel jack on the lower rear panel, and a high-current Anderson Power connector on the upper rear panel (KPA100). The low-current DC input is for a 3 amp (minimum) power supply that can power the K2/100 in QRP (low-power) mode, up to 15 watts. The high-current DC input is for a 20-amp power supply that allows operation at up to 100 watts. If a high-current supply is connected, the low-current supply is optional.

You can connect an emergency backup power supply at the lowcurrent input. Typically this would be a battery that is kept floatcharged. If the high-current supply ever fails, or the power mains go down, the K2/100 will immediately drop into bypass mode, and you'll be able to continue operating at QRP levels from the backup supply.

Two special status messages are provided in the case where two supplies are connected. If you turn off just the high power supply, you'll see N O P A P S (may take up to 10 seconds due to slow decay of the power supply voltage). If you turn the high-power supply back on, you'll see P A P S O N . The K2/100 will go in and out of bypass mode when the high-current supply is turned on and off.

High Current Power Supply Requirements

The high-current power supply should be rated at 20 amps or higher. You can use a switching or linear power supply, or, for portable use, a large battery. Switching supplies are compact and inexpensive, but may generate noise that can be heard in the ham bands, especially if you use wire antennas that terminate near the operating location with little or no feedline. If noise is a problem, use a linear supply.

Transmit/Receive Antenna Jacks

The K2/100 has two transmit/receive jacks: a BNC jack on the lower rear panel, and an SO239 on the upper rear panel (KPA100). The BNC connector is a QRP standard, provided with the basic K2 for use at up to 15 watts. The SO239 is the standard connector for high-power operation.

If the KPA100 is installed, you should use only the SO239 antenna jack. The BNC connector should be kept covered by the supplied rubber cap.

Receive Antenna

If you have the K160RX option installed, you'll have a separate receive antenna jack (BNC) on the lower rear panel. This input can be enabled on a per-band basis using the R A N T menu entry.

Ground

A ground thumbscrew is provided on the upper rear panel (KPA100).

Antenna and Antenna Tuner Considerations

The K2/100 can be used with coax-fed antennas or antenna tuners. In either case, SWR should be kept as low as possible. High reflected power (caused by high SWR) will result in an automatic reduction of power output by the transceiver. This is required to protect the power transistors. When the K2/100 reduces power due to high SWR, you'll see the message H I R E F L on the K2's LCD.

When an antenna tuner is being adjusted, it can present a very wide range of impedances to the power output stage. For this reason, initial tune-ups should be done in QRP mode (10 watts or less). Use only that amount of power required for your tuner to operate correctly.

The DC input jack on the KPA100 assembly, J3, is not switched. This means that 12-14VDC will appear on the KPA100 board anytime your external 20A supply is turned on. This is typical of most compact HF transceivers, and should not present a problem. The current drain from this power supply with the K2 turned off should be very low.

Note: If the POWER control is set above 20 watts, power will be temporarily set to 20 watts when you hold T U N E . This can be overridden by holding T U N E and D I S P L A Y together, or by adjusting

the POWER control after TUNE starts (see Controls, next page).

Page 50

Controls

High Power Configuration and Fan Control

High power (QRO) operation is controlled by the P A menu entry, located in the secondary menu. To access this menu, tap M E N U to

bring up the primary menu, then tap D I S P L A Y to select the secondary menu (S E C will flash on the LCD). Once you're in the secondary

menu, scroll to the P A entry using the VFO knob or the B A N D + and

B A N D - switches. To edit the parameter, hold E D I T .

The P A parameter has five possible settings:

• O F F puts the K2 in QRP mode (POWER range 0.1-15 W)

• O N is the normal setting (see POWER Control, below)

• F x . x x shows the KPA100 board's firmware revision

• E x x x shows KPA100 error status, if any (see Troubleshooting)

• t P A allows TUNE mode to display heat sink temperature (°C)

Whenever you're editing the P A menu parameter, you can also tap

D I S P L A Y to change the KPA100 fan mode:

• F A N n o r is the normal setting (goes to low or high if needed)

• F A N L o H i keeps the fan at low speed, going to high if needed

• F A N H i keeps the fan at high-speed at all times in QRO mode

Switches

R F / A L C : Use ALC meter mode only for testing, not continuously.

A N T 1 / 2 selects one of two antennas on the Elecraft KAT100 ATU.

T U N E puts the K2/100 into tune (key down) mode at no more than

20 watts, which protects the power transistors when an antenna tuner is being used. The 20-watt limit can be overridden by holding T U N E and D I S P L A Y together, or by adjusting POWER after TUNE starts.

Excluded Frequency Range

Transmit is disabled from 25.000 to 27.999 MHz in QRO mode.

PA KEY Output (KPA100, J7)

The PA KEY output can be used to key an external high-power amplifier T-R relay. (See Specifications for voltage and current limits.) You may want to use "8R HOLD" keying option to improve CW keying. Use the menu to set T - R to the desired delay time; tap

D I S P L A Y until you see 8 r h o l d on the LCD; then exit the menu.

Temperature Calibration (CAL tPA)

To exit parameter edit, tap M E N U once. You can then tap D I S P L A Y again to return to the primary menu if necessary (P R I will flash). Tap

M E N U again to return to the normal frequency display.

POWER Control

If P A is set to O F F in the menu, or there is no high-current power supply present, the POWER control range will be 0.1 to 15 watts. Each LED in the bargraph will represent 1 watt.

If the P A is set to O N , and a high-current supply is connected, the POWER control covers 0.1-110 watts. The lower third of the control's rotation provides 0.5-watt increments up to 10 watts (1 watt per LED bar). The upper two-thirds of the control's rotation provides 1-watt increments from 11-110 watts (10 W per LED bar). The bypass relays on the KPA100 will switch at the 10-watt point.

The maximum recommended power for data modes is 40 watts.

The C A L t P A function is used to calibrate the temperature sensor on the KPA100. See page 45 for instructions.

Transmit Warning Messages

If reflected power is too high in QRO mode, you may see H I R E F L on the LCD, along with an automatic reduction in power to a safe level (see antenna tuner considerations on previous page). If current is too high at either the K2's 10-watt stage or the 100-watt stage, you may see H I C U R , again accompanied by a power reduction.

CW Operation

During CW operation you may see the power output rise slowly to a few watts beyond the intended level, then drop back slightly below it. This is normal ALC behavior, and is intended to compensate for slight power gain changes as amplifier bias stabilizes.

Page 51

Remote Control using the RS232 Port

Control Board Preparation

If you have previously installed a KIO2 option in your K2, skip the steps on this page and continue with RS-232 Interface Setup and Test on page 52.

Turn off the K2. Before handling the Control board in the

following steps, touch a grounded surface.

Remove the screws that hold the K2 Control board to the front

panel board. Also remove the KAF2 audio filter board if present.

Use the long-handled Allen wrench supplied with the K2 to pry the Control board up at the point marked "LIFT HERE" on the RF board. Place the Control board in front of you, component side up.

Locate the K2 Control board revision letter, at the bottom righthand corner near P3 (top side of the board). If your Control board is rev. A (or XC, from the 1999 field test), you will need to modify it. If your Control board is revision B or later, skip the next four steps.

The trace between Q5-gate and U6 pin 25 must be cut as shown

above. This trace is located on the top side of the Control board. Once you have located the trace, use a sharp tool such as an X-acto

knife to make two small cuts near the location marked with an "X". Press down with the tip--don't draw the knife across the trace, since you may slip, cutting adjacent pads or traces. Next, pry up and remove the small segment between the cuts. Examine the trace closely to make sure the cut segment is completely removed.

Cut a 3/4" (19 mm) length of the supplied green-insulated hookup wire, and remove 1/8" (3 mm) of insulation from each end. Install and solder this jumper on the bottom of the board, between Q5-gate and U8 pin 4, as shown above. Make sure the jumper doesn't contact adjacent pads or component pins.

Solder a .001 µF, 0.2" LS capacitor ("102") across P4, pins 1 and

5. (Listed as Ctxd in the parts list.)

Prepare a 4" (10 cm) jumper using hookup wire. Solder it between U6 pin 25 and P4 pin 1 on the bottom side of the board (pin 1 is the round pad). Make sure the jumper doesn't touch adjacent pins.

Figure 39 shows the bottom side of the Control board, where

most of the changes will be made. One trace will be cut on the top side.

Cut trace on top side

Jumper, 3/4" (to pin 4 of U8, not to RP7)

Figure 39

Re-install the Control board (and KAF2 if applicable)

Jumper, 4"

Bottom view of Control board

.001 µF

Page 52

RS-232 Interface Setup and Test

Connect the KPA100 to the K2 Control board via the ribbon cable (see page 22). Also connect the KPA100 speaker cable (J5) to the K2 RF board.

Connect a low-current power supply to the K2's DC power input jack (lower rear panel).

Turn on the K2.

Tap M E N U and locate the S T L (sidetone volume) menu entry, then hold E D I T to edit the parameter. If no sidetone is heard (due to the Control board modification), tap D I S P L A Y to change the sidetone source to U 8 - 4 (default is U 6 - 2 5 ). If you still don't hear the sidetone, refer to Troubleshooting. Tap M E N U twice to return to the frequency display.

Turn off the K2.

KPA100 to Computer Cable Assembly

CAUTION: Do not use a pre-assembled cable of any

kind (printer cable, etc.) between the KPA100 and a computer.

Some of J8's pins provide special signals not intended for use with an RS-232 interface, and you could damage the K2, KPA100, or the computer if these lines are used incorrectly.

Locate the 4-conductor cable. The cable can be cut to a shorter length if desired, but it will work equally well at its full length (10', 3 m).

Remove 1/2" (12 mm) of the jacket from the cable. Be very careful not to nick the individual wires.

Peel back and cut away the foil shield.

The white wire will not be used for serial communications, but should be saved as a spare. Fold it against the cable jacket and secure it with tape.

Strip off 3/16" (5 mm) of insulation from each insulated wire.

Twist the strands of each wire together and tin them lightly with

solder.

Locate the DB9F (female) and DB9M (male) connectors. Arrange them as shown in Figure 40 (male connector on the right, solder cups facing up). Make sure the 5-pin rows are facing each other.

Clamp the DB9F (female) connector into a padded vise, if available.

As shown in Figure 40, pins 7 and 8 of the female connector can be wired together (using a discarded component lead) to provide RTS/CTS loop-back2. Some software requires this hardware handshaking. We recommend that you make this connection, unless you're sure that your application software does not need it. Some programs use these lines for CW keying, etc.

Clip the bare shield wire off at the PC end of the cable only. The shield wire will be connected at the K2 end.

Solder the RED, GREEN, and BLACK wires of the PC end of the cable (the end with no shield wire) to the female connector. Refer to Figure 40.

Remove the female connector from the vise, and insert the male connector. Keep this connector in the orientation shown.

Solder the BARE (shield), RED, GREEN, and BLACK wires to the male connector as shown.

Remove the male connector from the vise.

PC END (FEMALE)

1 1

RED

BLK

RTS/CTS LOOPBACK (SEE TEXT)

K2 END (MALE)

BARE

RED

GRNGRN

BLK

Figure 40

RTS = Request to send, CTS = Clear to send.

Page 53

Locate the connector housings (backshells) and associated hardware. Note: A single hinged backshell may be provided rather than a two-piece backshell.

Attach a backshell to the male connector (Figure 41). Use the provided cable clamp to hold the cable in position, then secure the clamp with two screws. The jackscrews must be retained by the shells. Secure the backshell halves with the provided hardware (or, if the shell is hinged, snap the backshell closed).

Attach a backshell to the female D connector.

JACK SCREW

CLAMP

Figure 41

BACK SHELL

You can use your logging or control program to verify that basic operations such as band or mode change are working. (See Software Configuration, following page.)

An alternative is to use a terminal program such as Hyperterminal:

• Run the terminal program. Set it up for 4800 baud, 2 stop bits (1

will also work), 8 data bits, no parity. Turn off hardware handshaking (RTS/CTS). If possible, turn on local echo and line- feed so you can see what you type.

• Tap M E N U and locate the P O R T menu entry as you did earlier.

Hold E D I T to enter edit mode.

• Tap D I S P L A Y to send a test message from the K2 to the

computer. A string of characters similar to FA00014020000; (VFO A frequency).

• Tap M E N U twice to exit the menu.

• At the computer keyboard, type SW01; (the semicolon is

required). This should cause the K2 to switch to the next higher band. Note: You cannot backspace and correct errors. Incorrect commands will be ignored.

If the K2 did not transmit and/or receive data as described above, or did not work properly with an application program, refer to

Troubleshooting.

Serial Interface Test

Connect the serial cable to the KPA10 (J8) and to the computer. Use a 9-pin to 25-pin adapter if required. Secure the cable at the computer using the jackscrews.

Turn on the K2 and computer.

Tap M E N U , then tap D I S P L A Y to gain access to the secondary menu.

Locate the P O R T menu entry using the B A N D + and B A N D - switches. To edit the parameter, hold E D I T , then change it from O F F to O N (using B A N D + / B A N D - ). Tap M E N U twice to exit.

Computer Control

Computer-Generated Noise Considerations

Computers and their peripherals can generate HF-range spurious signals. If you use coax-fed antennas, you may not hear any noise. However, if you use an wire antenna with a short feedline (or no feedline), you'll almost surely hear birdies or hash on some bands when the computer is on.

If computer-generated noise is a problem, you may have to improve your ground system, re-orient your antenna, move the antenna farther away, or use coax feed.

Page 54

Software Configuration

Table 1. Application software information.

The KPA100 is intended to be compatible with a wide range of existing PC-based logging, DXing, remote control, and contesting applications. However, we cannot guarantee 100% compatibility. In general, software used with the K2 should be set up as follows:

Radio Type: Elecraft K2

Interface: 4800 baud, 8 data bits, no parity, 2 stop bits (1 will also work)

Handshaking: Set to "None" if possible. No hardware handshaking is required.

Polling: Many programs periodically poll the radio to see if the operator has manually adjusted any of the controls. The K2 can respond very quickly to these requests, but we recommend a setting of 1-3 seconds to minimize possible computer noise. Polling during transmit is allowed, but we recommend turning it off if possible.

Table 1 provides details on setting up selected remote control and logging software for use with the K2. Check our web site additional information. Also available on the web is the Elecraft KIO2 Programmer's Reference, which you can consult when writing your own K2 control programs. The KPA100 and KIO2 serial interfaces are functionally identical.

Using Elecraft's K2REMOTE and K2VOICE PC Software

K2REMOTE provides flexible remote control of the K2, even over the Internet (using TCP/IP). K2VOICE is a voice feedback program for the K2 which make the K2 fully usable by hams who are unable to see the normal K2 controls and displays. You can download the programs and associated documentation from our web site.

If your software does not list the K2, select the TS-570D or the closest equivalent (950, 850, 50). The K2 can recognize a large subset of TS-570 commands. (TS-570 is a trademark of the Kenwood Corporation.)

Program K2 Configuration and Operating Notes

CT DOS program; requires a batch file to start up correctly (for

details see http://www.k1ea.com/hintkink.htm). In the batch file, use the command COMTSRx -Px -B4800 -N82 (e.g., x = 1 for COM1) Set Radio 1 to TS950 if K2 is not in the list. Optional: change bands from the K2 manually the first time so CT can store the values for VFO A and VFO B for each band.

DX4WIN Use Kenwood (generic) radio type, 4800 baud. Default

polling rate is 6000 msec with 6 retries, but 1000-2000 msec is recommended. Clicking on a DX spot may set the wrong mode. Don't use multiple-band scanning, since this could cause excessive relay wear.

K2REMOTE, K2VOICE

Log-EQF, Rig-EQF

MixW Version 2.02 and later includes K2 support (listed under

NA Run the "CONFIG" program. Select F4 (Serial Port Setup).

RCP570 TS-570 emulation; some controls not applicable to the K2.

T-R Log In the configuration file (.cfg), set: RADIO ONE TYPE =

TRX Manager

WriteLog Check the "Poll" box, and select No for "Comm PTT". YPLOG Specify 2-wire mode (RxD/TxD, no handshaking).

See descriptions on previous page.

A modified rig file for these programs that better supports the K2's RTTY and RTTY-reverse modes can be found on our web site.

Kenwood)

On the desired port, set baud to 4800, and set device to XCVR1. Select F5 (Equipment Configuration). Set XCVR #1 to KENWOOD1 Run NA. Go to the Equipment Control Panel and check Radio #1.

The program can take up to 30 seconds to turn on the radio display on start-up. Don't use SEND button (hangs the computer).

TS570 (Version 6.63 and later: use K2) Also add SHIFT KEY ENABLE = TRUE to use the right and left SHIFT

keys to change the receive frequency when RIT is on. Hitting both shift keys simultaneously resets the RIT to zero.

RTS/CTS loop-back required at computer end (pin 7 to 8).

Note: The program may send the K2 "FL" filter selection commands, which are not supported.

Page 55

CW Keying and PTT

Connecting Other Equipment to the KPA100

There are three basic ways to key the K2 when using a computer:

• Microphone, hand key, or paddle directly to the K2: This is

preferred if you don't use the computer to generate CQs and contest exchanges.

• Serial or parallel-port control line keying: Many programs

support this method. In SSB mode the computer turns a selected control line on to activate PTT. In CW mode, the computer generates the dots and dashes, turning the selected control line on and off in response. The control line(s) used--which may be at RS232 or TTL/CMOS levels--must be level-shifted for connection to the K2 key and/or mic jacks.

• "Virtual" keying, using computer commands sent to the

KPA100's serial port: In this case, no connection to the key or

mic jacks is required for keying the K2. In SSB mode, the computer sends the K2 "TX" and "RX" commands, which the K2 responds to by turning PTT on and off internally. In CW mode, the computer sends typed characters to the K2 using a "KY" command, and the K2 converts the characters to dots and dashes internally. This method of keying is supported by only a few remote-control applications, including Elecraft's K2REMOTE program. (For details on the TX, RX, and KY commands, refer to the KIO2 Programmer's Reference.)

For control-line keying, you can use the spare wire (white) in the 4conductor cable. You'll need to connect this wire to the specified control line at the PC end. At the K2 end, a level converter using an NPN transistor will be required (usually diagrammed in your program's user manual). The white wire must then be brought out from the connector at the K2 end and routed to a 1/8th inch stereo plug for the key jack. You can optionally use two diodes (or two transistors) to take advantage of the K2's "auto-detect" feature, allowing both the computer and a keyer paddle to be connected to the K2's key jack at the same time. Additional information on this topic can be found on our web site.

J8 provides a number of signals in addition to those needed for the RS232 serial interface (Table 2). Note: Use pin 1 as the electrical ground for any external devices. Pin 5 should only be used as the RS-232 ground return to the computer.

Table 2. J8 Signal Descriptions.

Pin Signal Notes

1 Chassis GND RF/DC ground 2 TxD RS-232 data from K2 to computer 3 RxD RS-232 data from computer to K2 4 -- Not connected 5 RS-232 GND RS-232 ground return 6 AuxBus K2 configuration network, intended for use

with AuxBus-compatible peripherals. Connections made to this line must be shielded, and total bypass capacitance should be between .001 and .005 µF.

7 RF Detect RF level feedback (DC), intended for use

with an external automatic antenna tuner. Improper use of this line could result in incorrect K2 power settings, high current, or other difficulties.

8 12CTRL This is intended as a power-on signal from

the K2, and/or for powering low-current external peripherals. Total load current should be kept under 50 mA continuous, 80 mA peak. A 150-Ω or larger series current limiting resistor should be used.

9 8 V Receive 8 V on receive, 0 V on transmit (approx.)

This signal is intended for use sequencing external amplifiers, although the use of the PA KEY output is preferred because it can drive amplifier relays directly.

Page 56

K2/100 Specifications

Downloaded by

RadioAmateur.EU

All measurements were made using a 13.8 V, 20-amp power supply and 50-ohm load. Numeric values are typical; your results will be somewhat different. Specifications are subject to change without notice. (Note: specifications in section 2 of the K2 owner's manual apply to the KPA100 except where superceded here.)

Keying Full break-in, diode switched

PA KEY output

Compatibility DC relay coil, pulled to ground

(do not use with AC-controlled relay)

Weight 5 pounds

Supply voltage 11 to 15 VDC, 13.8 V nominal

Current drain,

Receive

Transmit

Frequency ranges Same as K2, except 25-27.999 MHz

Spurious emissions Better than -40 dB @ 100 W

Harmonic content Better than -40 dB @ 100 W

Cooling 2-speed fan

These figures reflect the total current drain in receive mode. The current drain indicated on the K2's LCD in voltage/current monitor mode will be lower because some circuits on the KPA100 are powered from the KPA100's DC input jack. For details, see the Operation section of the this manual.

Current varies with band, supply voltage, configuration, and load impedance. External 20-A in-line fuse required if power supply does not include a fuse or circuit breaker.

Frequency counter cable removed. Adding the cable with the PA installed slightly increases spurious content on some bands. Keep the cable to the shortest possible length if it is installed (about 6").

The fan control circuit should not be used to directly drive a supplemental external fan.

PA OFF (QRP mode): 0.2-0.4 A PA ON (QRO mode): 0.3-0.5 A

15-20 A typ. @ 100 watts

transmit is excluded in high-power mode

Current 1 A

Voltage 200 VDC

RS-232 interface

Data rate 4800 baud

Format 8 data bits, no parity, 2 stop bits

Handshaking None required

ESD protection +/- 15 kV

Speaker

Internal 4 ohm, 3 watt

External Rear-panel mono jack

For CW operation with relay-keyed high-power amplifiers, you may want to use the "8R Hold" feature, which is described on page 50. Otherwise, the amplifier's T-R relays may switch too often.

Page 57

Troubleshooting and Repair

This information is specific to the KPA100 board. For other K2 troubleshooting, see Appendix E of the K2 owner's manual.

Replacing KPA100 firmware

If you upgrade your KPA100 firmware by replacing U1 (16F872), you must re-do the temperature calibration step (CAL tPA) on page 45. The temperature calibration constant is stored in U1's on-chip nonvolatile memory (EEPROM).

Replacing the power transistors (Q1, Q2)

Receiver problems

Noise: If you hear wide-band noise, or noise at certain frequencies,

especially noise that drifts in frequency, it may be caused by your power supply. Switching power supplies and computers often cause EMI across large portions of the HF spectrum. This will be especially noticeable if you use end-fed antennas with little or no feedline. The cure may be to use a linear power supply, relocate your computer, or switch to coax-fed antennas.

Loss of signals on all bands: If you don't hear anything on any band, or if all signals are generally attenuated, you may have a problem in the KPA100 T-R switch or SWR bridge. Also check relays K1-K2.

If you need to replace the RF power transistors, use only a matched set (request the Elecraft K2/100 PA Replacement Kit). Do not remove the old power transistors until you have read the instructions provided with this kit; you may damage the PC board.

General troubleshooting

If your specific symptoms are not covered below, do a complete visual inspection of the KPA100 board. Look for reversed diodes, leads not soldered (or not clipped), backwards ICs, and broken wires or components. Make the resistance measurements from earlier sections, and test all diodes in-circuit. Check continuity between the pads of all toroids (not the leads themselves).

Voltage Measurements

Table 3 and Table 4 provide voltages on all diodes, transistors, and ICs. Start with receive-mode (RX) measurements, then transmit-mode (TX) at low power (0-10 watts), and finally 11-110 watt TX mode. Be sure to observe all notes and cautions listed in the tables. Signal tracing is another possibility, but keep power set as low as possible, since RF probes are limited in the voltages they can safely handle.

PA menu parameter missing

Make sure KPA100-U1 is not installed backwards, and has no bent pins. Check all U1 voltages (see DC voltage tables). Also check the ribbon cable from the KPA100 to the K2.

Loss of signals on some bands: If you're missing signals on some bands but not all bands, look for a problem in the low-pass filter section. An inexpensive antenna analyzer can be very helpful. First, turn on the K2 and switch to the affected band, with POWER set for 10 watts or less (PA bypassed). Next, disconnect the RF cable running from the KPA100 to the K2, and insert a 47 or 51-ohm resistor into the 2 holes of the connector at the end of the coax cable (J1). Finally, connect an antenna analyzer to the KPA100's SO239 jack, and look at the SWR while sweeping the frequency across the band. If the SWR is poor, it probably indicates a problem with that low-pass filter.

Transmitter problems

H I C U R message: This LCD message indicates that the K2's 10-watt stage is drawing too much current. You should have CAL CUR set for at least 3.5 amps. Check all KPA100 T-R switch components, as well as R21-R23 (input equalization network), T1, and nearby components.

H I R E F L message: This LCD message will be flashed once (per

T U N E or band change) if the KPA100 has detected high SWR. When

this happens, the K2 reduces power output until reflected power is back to a safe level. H I R E F L warning may occur as low as an SWR of

1.5:1 at 100 watts, and at higher SWRs for lower power levels.

Excessive current from high-current supply: If the supply current exceeds 20 amps on one or more bands, you may have a problem with the associated low-pass filter. Current can also become excessive due to high SWR. Try improving the antenna matching or reducing power.

Page 58

Power output low: If power output is somewhat low across all bands, it may be because you used an inaccurate wattmeter during calibration of R26/R27. Other possibilities include incorrect bias adjustment (R6), reversed or poorly-prepared leads on T4, or a T-R switch problem (check D11-D14 and their voltages during transmit). If power is low on some bands, check the low-pass filters as described under Receiver Problems, above. Also note that many watt meters read too low on 160 meters even if they read correctly on the other bands.

E N D seen while transmitting: This usually indicates that you are out of band. Note: Transmit at high power is specifically excluded between 25 and 28 MHz.

Increasing temperature: If PA transistors temperature goes up when the PTT switch is closed, even while you're not talking, or if it increases in TUNE mode even with CW/TEST in effect, you may have the bias pot (R6 on the KPA100) set too high. Also check voltages in the bias circuitry. If these all check out OK, chances are that Q1 and/or Q2 have been damaged and will need to be replaced.

Miscellaneous

I N F O messages: If you see I N F O 0 8 0 or a similar message on the LCD, refer to the K2 Owner's Manual, Appendix E.

Missing 90-150 volt bias voltage or (-) RS232 driver voltage:

The most likely cause of this is a poorly prepared lead, or reversed leads, on T3. Next, check diodes D1-D8. These are located on the bottom of the PC board, but you can reach their pads easily from the top side (see Component Placement drawings).

RS232 I/O problems: Loss of K2 to computer data communication is often caused by a broken or poorly-soldered I/O connection, or by incorrect setup of the computer program. Verify the baud rate (4800) and related settings at the computer, and make sure the P O R T menu entry in the K2 is set to O N . Your software may require the CTS/RTS loopback. Also, some PC programs work only under DOS, or require extra serial port configuration steps.

Terminal program: There is a bug in some versions of Hyperterminal that prevents local character echo even if the appropriate box is checked.

Missing sidetone: The Control board modification changes the source of the sidetone to pin 4 of U8. The K2 needs to be configured to recognize the new source as explained on page 52. If the sidetone still can't be heard, re-check all Control board modification steps.

Table 3. KPA100 Diode DC Voltage Chart. Note 1: Caution--high RF voltages may be present.

Ref. Anode Cathode Ref. Anode

RX, 0-10w

D1 32 130 D11 14.1 1.5 14.1 1.6 139 128 139 0.8

D2 84 32 D12 14.1 1.5 14.1 1.6 135 128 135 114 D3 21 84 D13 14.1 1.6 14.1 Note 1 140 128 140 Note 1 D4 36 21 D14 14.1 1.6 135 0.8 135 0.8 135 114 D5 24 36 D6 13.7 24 D7 -22 -8.8 D8 -8.8 0.0 D9 14.1 13.8

D10 0.0 13.8

Anode

RX, 11-110w

Anode

TX, 0-10w

Anode

TX, 11-110w

Cathode

RX, 0-10w

Cathode

RX. 11-110w

Cathode

TX, 0-10w

Cathode

TX, 11-110w

Page 59

Table 4. KPA100 Transistor and IC DC Voltage Chart

Band=40m, DC supply voltage 14.1 VDC; power level 10w or less unless indicated. * = approximate and/or may fluctuate; @=depends on ext. amp control voltage; Note 1=depends on FWD/REF cal and SWR; Note 2: depends on 12PA supply voltage; Note 3=depends on Power level, 0-10w or >10w.

Ref. Pin VDC Ref. Pin VDC Ref. Pin VDC Ref. Pin VDC Ref. Pin VDC

Q1 RX E 0.0 Q1 TX E 0.0 Q12 G 13.8-0 U2 5 0.0 U5 1 0-4

B 0.0 B 0.57 Note 2 S 0-4 6 0.0 2 0-4 C 14.1 C 14.1 D 0-4 7 0.0 3 0-4

Q2 RX E 0.0 Q2 TX E 0.0 U1 RX 1 5 8 0.0 4 gnd

B 0.0 B 0.57 2 0.0 9 gnd 5 0-4 C 14.1 C 14.1 3 0.0 10 13.8 6 0-4

Q3 RX E 0.0 Q3 TX E 0.0 4 0.0 11 13.5 7 0-4

B 0.0 B 0.57 5 0.0 12 13.5 8 13.8 C 0.0 C 0.0 6 nc 13 13.8 U6 1 nc

Q4 RX E 0.0 Q4 TX E 0.67 Note 2 7 4 14 13.8 Note 3 2 0-4

B 0.45 Note 3 B 1.35 8 gnd 15 13.8 3 0-4 C 14.1 C 13.5 9 1.8 16 13.8 4 gnd

Q5 RX E 0.0 Q5 TX E 0.85 10 2.4 17 0.7 5 nc

B 0.0 (100w) B 1.4 11 5 18 13.8 6 0-4 C 14.1 (100w) C 13.3 Note 3 12 0, 5 U3 IN 13.8 7 5

Q6 RX G 5 Q6 TX G 0.0 RX, TX 13 0, 5 OUT 5 8 5

S 0.0 (100w) S 0.0 RX, TX 14 0, 5 gnd 0.0 U7 1 0-.8 D 0.6 (100w) D 115 15 0.0 U4 1 13.8 Note 3 2 14.1

Q7 RX G 0.0 Q7 TX G 5 RX, TX 16 0, 5 2 0.0 “ 3 14.1

S 0.0 (100w) S 0.0 Note 3 18 0, 5 3 13.8 4 gnd D 127 (100w) D 0.6 19 gnd 4 0.0 “ 5 0.68

Q8 RX E 0.0 Q8 TX E 0.0 20 5 5 -22 “ 6 0.68

B -2.5* B -2.5* 21 0.0 6 0.0 “ 7 0.4-1.4 C 11.6 C 11.6 22 0.0 7 13.3 8 14.1

Q9 RX G 0.0 Q9 TX G 5 23 0.0 8 -22

S 0.0@ S 0.0@ 24 0.0 9 0.0 D 0.0 D 0.0 25 4.9 10 0.0

Q10 RX G 0.0 Q10 TX G 5 26 0.0 11 5

D 0.0 Note 1 D 0-5 RX, TX 27 5.7,<0.3 12 5 S 0.0 S 0.0 U2 1 0.0 13 5

Q11 RX G 0.0 Q11 TX G 5 2 4.9 14 0.0

D 0.0 Note 1 D 0-5 3 0.0 15 5 S 0.0 S 0.0 4 0.0 16 5

Page 60

Circuit Details

Sheet 1

D11-D14, Q6, Q7, and related components form a high-isolation, full break-in T-R switch. D12 and D14 are forward-biased in receive mode; D11 and D13 are forward-biased in transmit mode. The "off" diodes are reversed biased by the high-voltage bias supply (90-150 V), preventing RF leakage across the inactive path. In QRP (bypass) mode, relays K1 and K2 route RF around the T-R switch, and both the transmit and receive diode paths are turned off to reduce current drain.

R21-R23, C82, and L18 form an equalization network that reduces the required drive power on higher bands while increasing them on the lower bands. This keeps the overall frequency response of the power amplifier relatively flat from 160-10 meters.

Matched PA transistors Q1 and Q2 are conservatively rated at the 100-watt power level. They are operated in push-pull, providing a high degree of even-order harmonic suppression. U7B and Q4 supply bias. Q4 is an emitter follower, and U7B provides closed-loop regulation of the voltage at the emitter of Q4. Q3, attached to the heat sink, provides temperature feedback, reducing bias at high temperatures.

In high-power (QRO) mode, Q10 and Q11 are turned on by the SCALE line from U1. This pulls RP1 pins 2 and 3 to ground, which, in combination with R24 and R25, divides the VFWD and VREFL voltages by approximately 3.16 (square root of 10). Since KPA100 power output is proportional to the square of the voltage at the VRFDET line, this in effect scales power up by a factor of 10.

RFC10 prevents build-up of any static charge at the antenna jack.

Sheet 2

Microcontroller U1 acts as a relay driver for the low-pass filter and bypass relays, and also gathers data from the SWR, current, 12V supply, and temperature sensors. It forwards this data to the K2 when requested, and can also signal the K2 when any monitored condition is out of range and may require a power reduction. This communication takes place across the K2's 1-wire network, the AuxBus, which is connected to pin 28 of U1. U1 also controls the fan, based on heat sink temperature, and drives the PA KEY transistor (Q9).

Unlike other AuxBus devices in the K2, which sleep during inactive periods, U1 runs continuously monitoring KPA100 sensors. For this reason, it uses a crystal oscillator rather than a ceramic resonator.

R7 and U7A form a current-sensing circuit. This is used by the microcontroller (U1, sheet 2) to check for excessive current drain.

L15, L16, and C64 form a high-pass filter that helps ensure amplifier stability. Its cutoff frequency is 1.5 MHz. The output of the high-pass filter is routed to the low-pass filters (sheet 2) via D13 and C79.

Following the low-pass filters is the forward/reflected power bridge (T4, D16, D17). Rectified DC voltage from the bridge is buffered by voltage followers U5A and U5B. U6 further buffers the VFWD voltage (forward power) and drives the VRFDET line, which is returned to the K2 for purposes of closing the ALC loop (for power control).

In low-power (QRP) mode, Q10 and Q11 are turned off (high impedance), allowing the full voltage from the bridge to reach the associated A-to-D converter inputs on the microcontroller. In this case, the bridge performs identically to the one in the KAT2 ATU.

Relays K3-K12 select one of the five low-pass filters. The relays drive lines from U1 are buffered by U2, which has diode-protected outputs.

The output of the 16.289 MHz crystal oscillator (Q8, X1, T3, etc.) is to derive the T-R switch bias voltage (90-150 V) as well as the negative voltage for the RS232 driver IC. D1-D8 are used in pairs for rectification and voltage doubling.

U4 is an RS-232 transceiver IC. It converts the 5V logic-level signals at pins 11 and 12 (RX and TX data) to RS-232 levels, typically +/- 5 to +/- 12 VDC.

P1 is the interface connector between the K2 Control board and the KPA100. The 12CTRL line (12 volts switched) is used to power the KPA100 fan, relays, HV bias supply, RS232 interface and SWR bridge. This allows these circuits to be used and tested even if a high-current power supply is not connected at J3.

Page 61

KPA100 Schematic

Downloaded by

RadioAmateur.EU

K2 RF

("AUX RF")

RF IN

GND

12V, 20A

(Ext. Fuse)

K2 12V

("AUX 12V")

12PA

R14

470

RFC5

100µH

C86

1N4007

.047

C67

.033

200V

15K

Bias Set

T SENSE

MJE182

12K2

GND

N:111

C76

.01

D11

1200

C82

R21 R23

R22

100

L18

1.2µH

T44-2

0.6-0.9 V

D10

1N5404

SB530

TP2

90-150V

R11

ZVN4424

C72 .01

D12

1N4007 1N4007

RFC3

100µH

510K

C71

.0018

200V

C77

.015

200V

R12

180K

C31 .033 200V

RFC11

100µH

ZVN4424

C73 .01

D14

T-R Switch

RFC4

100µH 5µH

C81

4700

10 1W

12PA

C66

180

C63 .047

C62 .047

C61 .047

C60100µF

R9 10

C85

.047

9:1

U7B

LMC6482

R32

100 1%

C33

0.1

3.6

R20

3.6

R19

4700

C80

MJE182

Current Sense

R7 .005 ohms

C34

0.1

R30

3.09k, 1%

C59

R39

68 2W

0.1

High-pass Filter

R38

C83

1200

s.m.

523

R35

R34

10 2W

2SC2879

C58

68 2W0.1

FB110-43

(2 beads)

C49

.047

2N3904

I SENSE

(0-5 V = approx. 0-32 A)

C30

0.1

U7A

LMC6482

C48

.047

12PA

R13 100

C75

0.1

L16

T44-2

L15

5µH T44-2

1:16

C57 .047

.047

C56

C55 .047

C54 .047

C53 .047

C52

.047

470µF

C51

25V

Not on the PC board.

= on bottom of PC board

1N5404

1800

200V

AF In

RFC1

100µH

D13

C64

Low-Pass Filters

C79 .039 200V

LPF OUTLPF IN

(SHEET 2)

SWR Bridge

C70

.001

T4-5

FT50-43

D16

1N5711

C87

.001

FWD REFL

R28

200

100K

T4-6

30pF

C95

100

D17

1N5711

R27R26

RFC10

100µH

C88

.001

Antenna

GND

R29

3.3K

GND Post

C69

.001

U5A

12CTRL

U5B

LM358

GND

C10

2.7 ohms

0.1

2.7 ohms

TP4

VFWD

R24

8.45K

RP1

3.9K

C11

0.1

R25

8.45K

SCALE

Q10 Q11

2N7000

RP1

3.9K

VREFL

SPKR

GND

Elecraft

W. Burdick E. Swartz

3.3K

R15

3.3K

KPA100

Rev. Sht. DateBy

E 5/13/02

R16

C89

.01

VRFEN

EL5146C

VRFDET

C65

.01

Ext. Spkr

SP1

Int. Spkr

1 of 2

C68 .01

Page 62

12CTRL

Downloaded by

RadioAmateur.EU

Ext. PA Key

Aux I/O

78L05

BIAS SET TEST POINT

TP1

I SENSE

C26

C27

4 MHz

30pF

12PA SENSE

RP1

3.9K

Q12

2N7000

123456789

TXD

RXD

C98

C99

.01

1 2 3 4 5

6 7 8 9

OUT

C23

0.1

VFWD

VREFL

T SENSE

VRFEN

SCALE

IRF830 or IRL620

VRFDET

12CTRL

C97 .01

(BACK VIEW)

MCU

PIC16C72

MCLR

RA0

RA1

RA2

RA3

RA4

RA5

VSS

OSC1

OSC2

RC0

RC1

RC2

14 15

RC3 RC4

10K

3.3K

RFC6-8: 100 µH

C7-C9, C32: .01 µF

RFC6

RFC7

RFC8

C32

RFC9

15µH

AUXBUS

C84

.001

RB7

RB6

RB5

RB4

RB3

RB2

RB1

RB0

VDD

VSS

RC7

RC6

RC5

12PA

RS232 Interface

VSS

GND

VRFDET

12CTRL

T3OUT

T3IN

RP1

3.9K

8 7

547

T2OUT

R3IN

R3OUT

T2IN

121415

/K2 RX

123456789

AUXBUS

8T (NC)

C25

.001

C90

.01

-5 TO -25V

12CTRL

391

T1OUT

R2IN

R1IN

R2OUT

R1OUT

T1IN

VCCVDD

/K2 TX

To Ctrl Board

AUXBUS

12CTRL

MAX1406

TD62083

or ULN2803

IN0

IN1

IN2

IN3

IN4

IN5

IN6

IN7

GND

FAN+

C35

0.1uF

16.289MHz

/OUT0

/OUT1

/OUT2

/OUT3

/OUT4

/OUT5

/OUT6

/OUT7

100

FAN

C41

COM

R31

200

1/2W

FAN-

C74 .01

C22

C29

.01

C12

C14 .01

C16

.01

C18

.01

C20 .01

High-Voltage Bias Supply

C39

C38

.01

100K

2N3904

C46

.01

C40

0.1

.01

C13 .01

C15 .01

C17 .01

C19 .01

C21 .01

C13-C21

12CTRL

Low-Pass Filters

L1 L2

160m

C24

.01

C2A

C2B

S.M.

C2C

S.M.

L5 L6

C2D C2E

S.M.

30/40m

LPF IN

C3B

C3A

C3C

C3E

C3D C3F

C3H

C3J

C3G

LPF OUT

17/20m

TP3

C4A

L10 L11

C4B

C4C

C4D

L12

C4E

K10

10/12/15m

K10

K11

K11 K12

C5C

L13 L14

C5D C5F

C5E

C5GC5BC5A

80m

K12

C28

.01

C6A

C6C

C6D C6FC6B S.M.

C6E

C6G

All relays are shown in the RESET (de-energized) condition.NOTES:

= on bottom of PC board (nearest the heatsink).

30V

432

R10

C44

.01

7T bifilar FT37-61

12CTRL

C42

.015 200V

80V

D3C37

C36

.015

200V

D1-D8 = 1N4148

C43 .015 200V

90-150V

Elecraft

W. Burdick E. Swartz

KPA100

Rev. Sht. DateBy

E 5/13/02

2 of 2

Page 63

Parts Placement Drawing

Downloaded by

RadioAmateur.EU

(Top Side)

C28

C11

C2E C2C

C12

C3J

L8 L7

L12

C2D

KPA100 REV B 2002 ELECRAFT

C37

C42

Q12

RP1

R25

C36 C43

C64

C23

C26

C57

C52

TD62083

16F872

R10

TP1

L16

(SOCKET)

C49

C50

C31

L18

RFC4

R24

TP4

C38

C39 C44

C35

C70

R26

100K

C69

R27

C2B

100K

C2A

C3A

L10

C51

D13

C59

C58

C81

C80

D11

R15

R16

R20

R19

R31

C89

C30 C33 C34

C60

R35

C66

R34

C67

C68C25

MAX1406

BIAS SET

C82

GND

R32R30

C61 C62

C63

T1-4

T1-5

R23

R22

R21

C48

D12 C86

D14

C76

K1 D9

R14

RFC8 RFC6RFC7 RFC9

C7 C9C8

RFC1

C90

C71

R13

Q6 Q7

C72

C73

FANFAN+

C10

C77

C6G C6F

L11

TP2

C79

C95

D17

C6E

R29

C6D

D16

C88 C87

GND

T4C1

C6C

K11

C85

Page 64

Parts Placment Drawing

Downloaded by

RadioAmateur.EU

(Bottom Side)