Heathkit Service Bulletins: SB-102 (Complete 1966-89) -------------------------------------------------------------------------------- Joseph W Lutz (joelutz@JUNO.COM) Fri, 3 Apr 1998 13:37:36 -0800 Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] Next message: William Lockwood: "Frequency Counter IB-1101" Previous message: Sir Robin: "Re: Heathkit GDO" -------------------------------------------------------------------------------- November 25, 1970 SB-102 Bulletin No. SSB Transceiver SB-102-1 Meter Zeroing Original 10-147 control tolerance not sufficient to allow zeroing in all units. This part is being respecified to a closer tolerance. In the meantime, any field problems requarding zeroing of the meter can be corrected as follows: Change: R-107 from 100K Ohm to 82K Ohm [PN 1-159]. -------------------------------------------------------------------------------------------------------------------- September 14, 1972 SB-102 Bulletin No. SSB Transceiver SB-102-2 Repeated Heterdodyne Oscillator Tube Failure Change: R-212 from 220 Ohm to 330 Ohm 1/2 Watt resister [PN 1-4]. -------------------------------------------------------------------------------------------------------------------- March 23, 1973 SB-102 Bulletin No. SSB Transceiver SB-102-3 Low Grid Drive - Alignment Problems This has been related to the differences [internal electrode capacitance] between Tung-Sol & RCA 6146's. Purchasing has ceased buying Tung-Sol tubes; all new stock since late 1972 will be RCA's which give better performance. In addition, an additional alignment sequence is being put into the manuals which insures adequate gride drive -- previous tune-up was done in receive only where the peaks were broader than required for transmitter tuning. The new procedure uses the receiver sequence to get in the "ball park"; the added sequence peaks for maximum grid drive. The following modifications to the manual will help avoid the many questions: PAGE 103: 8th step, right column, last two sentances: Then turn the meter switch to GRID [grid current]. The meter should have some up-scale indication. The meter may read as much as full scale -- this is normal. PAGE 104: left column #2: Turn the meter switch to GRID & adjust the MIC/CW LEVEL control for a grid current reading, just enough so a peak may be seen when making the adjustment in the next step. PAGE 104: Right Column #4 - will be deleted. PAGE 119: Right Column #14 - will be deleted. ---------------------------------------------------------------------------------------------------------------- March 30, 1973 SB-102 Bulletin No: SSB Transceiver SB-102-4 LMO Instability We have a possible cure for some of the LMO instability problems in the SB-102. The following should help eliminate any stress on the LMO chassis when installed on the main chassis. Remove and discard the lockwashers & nuts used to mount the LMO to the chassis. Use instead a #6 flat washer [PN 253-25] & hex lock not [PN 252-27] at each lug, tightening each lug A TURN AT A TIME in a criss-cross pattern. We recommend this be done on all SB-102 units in for service even if customer has no complaints about LMO. ---------------------------------------------------------------------------------------------------------------- October 29,1973 SB-102 Bulletin No: SSB Transceiver SB-102-5 Low 40 Meter Output 1. REMOVE the 1-1/2" bare wire from hole 1 on the DRIVER PLATE circuit board & the ground foil of the RF DRIVER board. 2. Connect a 3/4" bare wire between the ground foils of these same two boards. 3. REMOVE the 1-3/4" bare wire from hole 1 in the DRIVE GRID circuit board & the ground foil of the RF DRIVER board. 4. Connect a 3/4" bare wire between the ground foils of these same two boards. 5. Remove the 2-3/4" bare wire which ties the groundfoils of the circuit boards to the shields. 6. Remove the coil cover. Then REMOVE four of the light spring clips & their hardware as shown: [[[NOTE: the pictorial shows removal of the set of clips & hardward located directly down from the 2 holes in the cover; the other set to be removed is directly across and down from the 3 holes in the cover.]]] 7. Readjust the driver grid & drive plate coils as instructed on page 102 in the SB-102 manual. ------------------------------------------------------------------------------------------------------------------ May 23, 1974 SB-102 Bulletin No: SSB Transceiver SB-102-6 SB & HW Series Audio Preamplifier & VOX Circuit Trouble Shooting Guide. It is assumed that the basic steps such as making DC voltage measurement, checking tubes & reviewing the soldering have been completed. The following information was compiled from the above transceivers in the 80M LSB position. The mike level control was at the 9:00 o'clock poisition. AC signal voltages are listed below. These voltages were measured from the microphone connector through the VOX circuit. All measurements were made with a VTVM. A microphone or audio generator for .1V @ 1KHZ can be used as the signal source. Mike Connector Lug 1 .1VAC Pin 2 of V1 .02VAC Pin 6 of V1 10-15VAC Pin 6 Level Control 10-15VAC Pin 5 Level Control .5VAC Pin 9 of V1 .2VAC Pin 8 of V1 .1 - .3VAC Center Arm of VOX Sensitivity Control 5-15VAC Pin 7 of V17 5-10VAC Pin 6 of V17 40-50VAC Junction of C211-D201 40-50VAC Pin 9 of V12 9-15VAC By tracing the AC signal from stage to stage the point of trouble can be isolated & steps taken to correct it. POSSIBLE TROUBLE AREAS - Check each of the shielded cables for a possible open or poorly grounded shield. - Check for continuity through each of the shielded cables. - Check for a proper ground at the mike control level. - If the frequency response of the audio stage is not within specifications check the values & installation of C1, C2, C3 & C9. - A change in VOX delay after operating for a period of time can be caused by leakage in diode D201. The other possibility is a change in value of capacitor C213. Either component could experience a change in operation characteristics due to heat. ----------------------------------------------------------------------------------------------------------------- May 23, 1974 SB-102 Bulletin No: SSB Transceiver SB-102-7 SB & HW Series Instability & Corrective Information. We suggest you check for each of the following possible causes: 1. Intermittent, rosin or cold solder joints. 2. Loose hardware at the tube sockets, terminal strips, circuit boards, shields and rear panel sockets. 3. Poor lead dress at tube sockets V8 & V9. The component leads must be short as possible. 4. Check C925 (Final tune capacitor) to be sure it is isolated from the tuning shaft. This is to prevent RF from traveling on the shaft to the front panel. 5. Check all edges of the final enclosures for proper grounding to the main chassis. 6. Check the hardware for the side rails to be sure a good ground is being provided. 7. Be sure that all the ground clips on the coil cover are making good contact with the switch shields. 8. Check the soldering of the switch shields to the center pins of tube sockets V6, V7, V10 & V11. 9. Check the ground leads from the switch board & shields, to be sure they are going to ground foil & not to the preselector capacitor foil pods on the RF driver board. 10. Check for broken or shorted pigtails on each of the shielded cables in the unit. 11. Check RFC801 & L901 for any signs of deterioration or physical damage, (burn spots). If apparent replace the part. 12. Improper adjustment of the Het. Osc. coils could cause improper mixing action, resulting in the final operating at a different frequency appearing as instability. 13. Change driver & final tubes then reneutralize per manual instructions. 14. Check driver tube shield to be sure that it has a good ground contact with the socket spring clip. 15. Check for a good ground between the front panel & chassis. 16. Check the SWR of the antenna system at the frequency of opertion. Should be below 2:1. 17. Check the antenna coax for leakage, poor connectors & broken shield connections. 18. Is the transmitter properly grounded? 19. Be sure all shields & tube shields are installed. 20. Realign using a properly terminated 50 ohm non-reactive dummy load. NOTE: This does not include a light bulb. 21. Check for normal Het. Osc. test-point voltage. 22. Check for proper LMO injection voltage 1.0-1.5 VRF. 23. Check for a high AC ripple content in the LV-B+, HV-B+ and bias voltages from the power supply. 24. Check to be sure that the shafts do not touch each other in the insulated coupling, and that the set screws do not touch the PA shield. 25. Check to be sure that the PA tune shaft turns the variable capacitor & is not slipping in the insulated coupling. ------------------------------------------------------------------------------------------------------------------- May 23, 1974 SB-102 Bulletin No: SSB Transceiver SB-102-8 Alternate Method of Neutralizing The Final Amplifiers NOTE: Be sure unit is off and power supply high voltage capacitors are discharged. 1. Disconect final plates & screen grid.*** 2. Turn unit on. 3. Rotate the BAND switch to 28.5. 4. Place the VTVM RF probe in the ANTENNA connector.** 5. Set the FUNCTION switch to TUNE. 6. Rotate the LEVEL control fully clockwise. 7. Adjust the PRESELECTOR control for a maximum reading on the VTVM. 8. Adjust the FINAL control for a maximum indication on the VTVM, with the LOAD control set at the 50 ohm position. 9. Using an insulated screwdriver, adjust neutralizing capacitor for a MINIMUM indication on the VTVM. 10. Readjust the neutralizing capacitor for a minimum indication on the VTVM. 11. Turn the FUNCTION switch to the off position. 12. Discharge high voltage power supply capacitors. 13. Reconnect final plates & screen grid. **VTVM & RF probe will be needed. ***To remove screen voltage in SB-100, SB-101, HW-100 & HW-101 disconnect R920 (100 ohm resistor) from buss wire between pins of V8 & V9. In the SB-102 removal of accessory plug is all that's required. To remove high voltage in SB-100, SB-101 & SB-102 disconnect red wire at lug 4 (in Sb-100 lug 3) of terminal strip BK that goes to grommet BL. In HW100 & HW101 disconnect red wire going to lug 1 of RF choke in final cage. NOTE: Take adequate steps to eliminate any possible contact with B+ or B+ shorts to chassis after disconnecting wire & resistor. ----------------------------------------------------------------------------------------------------------------- December 18, 1974 SB-102 Bulletin No: SSB Transceiver SB-102-9 Oscillations or Low Drive Loose boards cause sporatic self oscillations & unstable RF conditions, particularly at the high [15 & 10 meter] bands. The comb brackets which ahve been used are aluminum & could not be soldered. Steel brackets are now available [PN 204-2096] & should be used whenever encountered in the field. Both the switch shields & the driver boards should be soldered to these brackets. This change helps to increase grid drive as well as increase stability. ---------------------------------------------------------------------------------------------------------------- May 2, 1975 SB-102 Bulletin No: SSB Transceiver SB-102-10 Self Oscillations Occurring After Installation of Steel Comb Brackets. It has been found that in a number of units, self oscillations are still occurring after installation of both steel comb brackets [PN 204-2096]. To correct the condition, the screws around the RF driver board must be tightened securely. Also, the lockwashers between the circuit board & chassis must be installed, otherwise a good ground is not assured. Retightening screws which are already snug will also cause these oscillations to disappear in units where it is a problem. -------------------------------------------------------------------------------------------------------------- June 5, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-14 Relays Remain Energized After Transmit Condition After keying the transceiver with PTT for thirty to forty seconds, a positive voltage in excess of 10 volts appears at the control grid, pin 9 of V12, thus keeping the relays energized. To correct the problem, replace V12 [PN 411-124]. IEC brand tubes have been found defective in several cases, but other brands may also cause this problem. --------------------------------------------------------------------------------------------------------------- June 5, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-15 Poor AGC Action Leakage in the 6HS6 tubes [PN 411-247] at V10 and/or V11 has been found to cause: - poor AGC action - Fast S-meter decay - poor sensitivity when RF gain control is fully clockwise. This usually occurs after warmup of at least an hour. A positive voltage, usually over 1 volt, will appear at the grid, pin 1, of either one or both tubes. Replacement of the tube with the positive voltage corrects the problem. ---------------------------------------------------------------------------------------------------------------- June 5, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-16 100KHZ Calibrator Spurs Strong signals may occur at other than 100khz points. Look at the calibrator output [ahead of output diode] with an oscilloscope. Use high input gain and a slow sweep speed. If the upper portion of the sine-wave signal appears choppy or uneven, the Y201 crystal may be at fault. After installation of a new crystal [PN 404-43], recheck with oscilloscope. ---------------------------------------------------------------------------------------------------------------- July 24, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-17 Poor Preselector Tracking This problem is more noticeable on the 10-meter band. It may be caused by the drive belt slipping or by one of the variable capacitors not turning due to excessive friction inits bearings. Check the belt for being loose or worn and replace as needed. Lubricate the bearing of the variable capacitors. If lubricating the capacitor bearings does not allow the rotor to turn freely, replace the capacitor [PN 26-122]. ------------------------------------------------------------------------------------------------------------------ July 24, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-18 Carrier Nulls with IC14 Trimmer Plates Completely Meshed If C14 nulls the carrier with its plates fully meshed toward V2 [to the right], relocate C18, 12pf capacitor, to the other section of the null trimmer [C14]. ----------------------------------------------------------------------------------------------------------------- August 7, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-19 Relays Chatter In VOX Mode This may occur when the VOX gain is in the near-full CW position with the MIC level advanced past the 12 o'clock position. Also, the unit will not return to receive when the operator stops talking. Check the tube at V1. A "GE" tube will tend to oscillate, thus causing the above problem. Other 6EA8 tube brands should operate properly at V1. ---------------------------------------------------------------------------------------------------------------- August 7, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-20 Loading Capacitor Turns As Plate Capacitor Is Rotated This problem can be caused by: - Insuffiecent friction in the loading capacitor or; - Excessive friction between the plate and load tuning shafts. If the problem persists after freeing and lubricating the shafts, install a rubber grommet [PN 73-3] on the loading capacitor shaft between the pulley and the RF cage. Apply slight pressure to the grommet as the pulley set-screw is tighted. This will add enough friction to keep the loading capacitor still while tuning the plate control. Use only as needed. -------------------------------------------------------------------------------------------------------------- August 7, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-21 "Chirping" & Slow Receiver Recovery If "chirping" of the audio in the receive mode and slow recovery of the receiver after long periods of transmitting are encountered, remove the cover of RL2 and check for carbon buildup at the base, just below the contact. Clean dirt or carbon tracks, or replace if necessary. A dirt or carbon buildup will cause the +300 volts to be applied to adjacent contacts such as the bias or AGC lines, adversely affecting receiver cutoff by upsetting the operation of 1) V12, receiver mixer; 2) V10, RF amplifier; and 3) V11, first receiver mixer. -------------------------------------------------------------------------------------------------------------- August 22, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-22 S Meter Drift If the S meter drops below zero and pins after 1/2 hour of operation, there may be leakage in one or more of the following tubes: V3, V4, V10 or V11. New RCA tubes may exhibit the same problem. The following procedure will aid in finding the leaky tube: 1. Disconnect R415 to isolate V3 and V4 from the AGC line. Monitor the control grid at P1 of V3 for several minutes. If the voltage drifts in the positive [+] direction, V3 or V4 is leaky. Proceed to step 2. If the voltage remains stable, go to step 5. 2. Remove the white/blue wire from pin 2 of T102 and repeat the test. This will isolate V4 from V3. If the voltage still drifts, V3 is at fault. 3. To verify, reconnect the white/blue wire and then disconnect R101. Monitor the voltage at pin 1 of V4. The voltage should remain stable. 4. Reconnect R415 and R101. 5. Disconnect R408 and check the voltage at pin 1 of V10. If voltage drifts, replace V10. If the voltage is stable, replace V11. 6. Reconnect R415 and R408. Straight substitution with new tubes may not work if more than one tube is causing the problem, since even a small leakage can cause the drift. When you replace a tube, check for stable voltage at its control grid. Replace with the tube which gives most stable voltage. ------------------------------------------------------------------------------------------------------------ September 26, 1978 SB-102 Bulletin No: SSB Transceiver SB-102-23 Poor IF Sensitivity Check C101. It may have inadvertently been wired to point 2. It should be wired to point 15. It is an "easy-to-overlook" wiring error that would cause the transceiver to have low if sensitivity which would result in poor receiver sensitivity and low power output. ------------------------------------------------------------------------------------------------------------------- April 25, 1979 SB-102 Bulletin No: SSB Transceiver SB-102-24 Low Power Output; Poor VOX Sensitivity It has been determined that Sylvania, RCA and Westinghouse brand tubes do not functionproperly at locations V3 and V4. The brands found to work at other locations are: El-Menco, IEC, General Electric and Realistic. Westinghouse tubes at other locations throughout the unit may cause low power output and VOX problems. It is suggested not to use Westinghouse tubes at all. ---------------------------------------------------------------------------------------------------------------- September 20, 1979 SB-102 Bulletin No: SSB Tranceiver SB-102-25 Low Transmitter output; Low Receiver Sensitivity When cleaning the unit during prework [tube sockets, potentiometers, etc.], don't overlook the SSB/CW filter slide switch located with the RF gain control. This switch handles both transmit and receive signals and dirt and grease build-up can affect the performance of both functions. -------------------------------------------------------------------------------------------------------------------- January 21, 1980 SB-102 Bulletin No: SSB Tranceiver SB-102-26 Low Grid Drive on Certain Portions of One or More Bands + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- March 7, 1980 SB-102 Bulletin No: SSB Tranceiver SB-102-27 Finals Will Not Neutralize; C913 at Maximum Capacity + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- April 10, 1980 SB-102 Bulletin No: SSB Transceiver SB-102-28 Germanium Diode Change + + + + Information not yet available + + + + ------------------------------------------------------------------------------------------------------------------- November 13, 1981 SB-102 Bulletin No: SSB Transceiver SB-102-29 Tone in Audio when Switched to CW; Relay Chatters when Key is Closed + + + + Information not yet available + + + + -------------------------------------------------------------------------------------------------------------------- September 21, 1984 SB-102 Bulletin No: SSB Transceiver SB-102-30 S Meter Drifts; IF Oscillates Check the brand of 6AU6 tubes at V3 and V4. If a brand other than GE is used at these locations, replae them with GE brand tubes. Parts Replacement will stock only GE brand of 6AU6 tubes [PN 411-11]. ------------------------------------------------------------------------------------------------------------------ That is all that I have on the SB-102 up to 1989. Enjoy! 73 de Joe W7LPF/4 [NNN0KUU] QWCA - SOWP - NCVA - FISTS - RCC Gordonsville, Va 22942 [Orange Co] 73 de JOE- - - - - - - - - - -W7LPF/4 (NNN0KUU)- - - - - - - - - - - - - - -QWCA - NCVA - SOWP - FISTSGordonsville, Va 22942 (Orange County)Looking for: Heathkit HR/HX-20, MR/MT-1, Central Electronics 100V or 200V- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866] -------------------------------------------------------------------------------- Next message: William Lockwood: "Frequency Counter IB-1101" Previous message: Sir Robin: "Re: Heathkit GDO" --------------------------------------------------------------------------------