ELECRAFT KSB2 SSB ADAPTER Assembly and Operating Instructions Revision G, July 2, 2011. Copyright © 2011, Elecraft; All Rights Reserved Introduction The KSB2 option provides the Elecraft K2 with single-sideband transceive capability. With the KSB2 installed, the operator can use digital communications modes such as RTTY, packet, SSTV and PSK31 in addition to SSB voice. The KSB2 includes a 7-pole crystal filter optimized for SSB transmit and receive. This filter is always used for SSB transmit.
Parts Inventory The table below lists all parts in the kit. The K2 Owner's manual has photographs of similar parts. Ref.
Components on KSB2 Module, continued R21 R22 R1 RP3 RP1,RP2 RP5 RFC1,RFC2 T1 T2 U1 U2 U3 U4 U5 U6 X1-X7 Z1 Resistor, 68K, 5%, 1/4-watt (blue-gray-orange) Resistor, 560K, 5%, 1/4-watt (green-blue-yellow) Potentiometer, 1 M trimmer ("105") Resistor network, 2.0 K, 3 R, 6 pins (77063202 or 980663202) Resistor network, 2.7 K, 4 R, 8 pins (77083272) Resistor network, 47K, 5 R, 6 pins (61473) Toroidal inductor, 19 turns on FT23-43 core (0.23") Toroidal transformer on FT37-43 core (0.
Firmware Upgrades If you received new main-processor firmware (U6 on the K2 control board) along with your SSB adapter, you should install and test it before proceeding with assembly. The SSB adapter requires main processor firmware revision 1.04A or later. (Hold any button on power-up to check your revision number.) See separate instructions that were supplied with the firmware upgrade. BFO Crystals If you have a field-test K2 (s/n 1-100), you should have received two replacement BFO crystals.
The KSB2 PC board uses close-spaced components in the crystal filter area to minimize stray signal pickup. Some capacitors are assigned letters rather than numbers, and some components are not labeled. Place the KSB2 PC board in front of you as shown below. At the far right end of the board, you'll find an area with a very symmetrical layout. This area contains the SSB crystal filter and filter switching components.
KSB2 PC Board Assembly i A fine-point, temperature-controlled soldering iron (700-800 deg. F, 340-370 deg. C) is required to assemble this kit, due to the high density of the PC board layout. A highwattage iron or one with a wide tip may damage components, pads, or traces. Use a minimum amount of solder to avoid ground shorts. i To avoid difficulties in soldering adjacent components, install components only in the order described below.
Install all of the lettered capacitors shown below (CC, CM, etc.). After inserting each capacitor, bend its leads slightly to hold it in place. Limit soldering time to 2 or 3 seconds per lead, using a minimum amount of solder to avoid ground shorts. __CC and __CG and __CE and __CA and __CF and __CM (27 pF, "27" or "270") __CH (39 pF, "39" or "390") __ CK (39 pF, "39" or "390") __ CP (39 pF, "39" or "390") __ CJ (100 pF, "101") Install short wire jumpers at CD and CL.
i All diodes will be installed vertically as shown below. The anode lead will be inserted into the pad enclosed by a circle. The cathode lead (banded end) must be folded down and inserted into the adjacent pad, which is connected to the first pad by a white line. When installing diodes, check the Parts Placement Drawing as needed to make sure that you're inserting the leads into the correct pads. Install D3 and D4 (1N4148), both of which are near U5.
U3 is a surface-mount IC that should already be installed on the top side of the board (SSM-2166). Examine U3 with a magnifying glass to verify that all leads are soldered. Install U6, the 78L06 voltage regulator IC. This device has a plastic package like a transistor. The flat side must face the U6 label as indicated by the component outline. Install the 28-pin socket for U1. The notched end goes towards the left edge of the board. Install the 8-pin DIP ICs, U2 through U5.
__R4 __R20 __R21 __R22 __R23, __R24 (56K, green-blue-orange) (18K, brown-gray-orange) (68K, blue-gray-orange) (560K, green-blue-yellow) (10K, brown-black-orange) Re-check the values of capacitors CG and CH (39 pF). Once the crystals are installed (following steps) it is difficult to gain access to these two capacitors. Locate the envelope containing the matched SSB filter crystals (X1-X7). On the outside of the envelope you'll find a calibration number that ranges between 3.2 and 3.9.
i T1 and T2 are toroidal transformers, with two numbered windings: 1–2 and 3–4. These numbers are printed next to the pads on the PC board, and they also appear on the schematic drawing. T1 will be wound on a ferrite core (FT37-43, 3/8” [9.5 mm] diameter). For the larger winding, 3-4, use 22 turns of red enamel wire (13”, 33 cm). This winding will occupy about 80 to 90% of the core, as shown in the drawing below. (The drawing shows only 14 turns on the 3-4 winding.
i Very small ferrite cores are used for RFC1 and RFC2 to minimize stray signal coupling. These cores are a little harder to work with than larger cores, and are also more fragile. If you find it necessary to hold them with a vice, use only plastic or rubber jaws and a minimum of pressure. Inductor RFC1 is wound with 19 turns of red enamel wire (9" [23 cm]) on an FT23-43 core.
KSB2 Module Installation Remove the top and bottom covers. (Do not remove the heat sink.) Disconnect and remove the frequency counter probe. Locate the 5-crystal CW filter on the K2 RF board (X7 through X11). If any ground wires are soldered to the tops of these crystals, re-locate them to the sides of the crystals, about 1/4" (6 mm) up from the surface of the PC board. Note: There are two ground pads for each of these crystals (one on either side). For best performance, solder two wires to each crystal.
Install the 3/8" (9.5 mm) standoff on the top of the RF board as shown below, using three split lock washers and a 1/4" (6 mm) machine screw. The hole for the standoff is near the BFO test point (TP2). i If you have difficulty getting the screw threads started into the standoff, hold the standoff with pliers on one side while pushing and turning the screw from the other with a phillips screwdriver. Once the lock washers start to compress, the screw will mate adequately with the standoff.
Initial Test Turn on the K2 and verify that you see the usual ELE C R A FT display. If you see IN F O 0 8 0 or no display, you may have the SSB adapter plugged in incorrectly. If it appears to be installed correctly, unplug the adapter and look for a short to ground on one of the pins of P1. Tap the M E N U button, then use the B A N D + / B A N D - buttons to get to the SSB A and SSB C menu entries.
BFO Setup for LSB/USB Tap the B A N D - button to see the BFO setting for the first SSB filter (BF1). You should see a display similar to B F1 t 1 2 0 L . The BFO frequency control parameter (in this case 1 2 0 ) has a range of 000-255. (A lower-case letter t appears in the BFO display for BF1, e.g. B F1 t 1 2 0 L . This is a reminder that on transmit, BFO setting B F1 is always used, regardless of how you set the BFO for FL2 through FL4.) Tap D I S P L A Y to show the present LSB BFO frequency in kHz.
Microphone Configuration Follow the steps below to configure the K2 for your microphone. 1. If the Front Panel assembly is plugged in, remove the appropriate screws and unplug it. There are two screws holding the Front Panel board to the Control board, and four chassis screws that hold the Front Panel assembly to the chassis. 2. Place the Front Panel board upside-down on a soft cloth, with P1 to your right.
Table 2. P1 Wiring for Selected Microphones (NC = no connection). Elecraft MH2, MD2, Proset-K2 Mic kit includes 8 jumper blocks for use at P1, plus a 5.6-k resistor. Install the jumpers first, then solder the resistor from pin 1 to 6. Note: Do not attempt do disassemble the microphone. Signal AF Mic pin 1 (resistor to pin 6) PTT 2 DN 3 UP 4 FUNC 5 5V 6 GND 7 GND 8 Yaesu (MD-1, MH-1, 27, 31, YM-35, MD-100) Kenwood (MC-43,47,48,60), Alinco EMS-11 Do not connect pin 5 unless mic has internal preamp.
Alignment If your K2 serial number is 2999 or lower: Locate the PA Bias control, R60, on the K2's RF board near the PA transformer. Set R60 fully counter-clockwise. (Newer K2s have a fixed resistor at R60.) Locate the carrier balance control, R1 on the KSB2 module. Set it close to the center of its range. Turn on power to the K2. Select 40 meters, LSB mode, and filter FL1. Set RF GAIN = max. Coarse Carrier Balance Adjustment Disconnect the microphone.
Filter Setup Connect the K2's internal frequency counter probe to TP2 (BFO). Select 40 meters, LSB mode, and filter FL1. (It's important to always do filter setup on 17 m or below to avoid confusion due to the K2's sideband inversion above 17 m. The settings apply to all bands.) Set up your filters exactly as shown in Table 3 (below), using CAL FIL. Both the filters (FL1-4) and BFOs (BF1-4) must be set up for each operating mode.
Using The SSB Adapter Basic SSB Setup Mode Selection: To use SSB, select LSB or USB using the M O D E button. Tap A G C to select SLO AGC (recommended for all data modes). Filter Selection and Setup: Use the X F I L button to select the desired receive-mode crystal filter. In SSB modes you'll usually select FL2 , since the BFO settings for this filter have been optimized for receive (see Table 3). In transmit, the BFO settings for FL1 are always used, regardless of what receive filter is selected.
Power Control and ALC Tracking ALC: SSB transceivers use Automatic Level Control (ALC) to reduce transmit drive if output exceeds a desired level. Many transceivers require that you adjust the mic gain manually until the ALC indication is in a certain range. The K2's ALC is different: the drive level is automatically adjusted, over time, to keep ALC close to the optimal level. This tracking ALC (TALC) eliminates the need to adjust mic gain in most cases.
Troubleshooting If you have difficulty during test or alignment, do the following: 1. 2. 3. 4. Check the orientation of all ICs, diodes, transistors, electrolytic capacitors and resistor networks. Look for unsoldered pins, solder splashes, or shorts to ground, especially in the area of the crystal filter. Measure resistances to ground in the crystal filter area, checking each crystal, both resistor networks, all diodes, numbered capacitors, and R5.
