November 1, 1967HW-100 Bulletin No: SSB Transceiver HW-100-1DImproper tuning Delete: [2] 26-109 [2] Variable Capacitor, 2 Sect. P.C. Mtg Add: [2] 27-122 [2] Variable Capacitor, 2 Sect. P.C. Mtg Delete: [4] 85-131-1 [1] PC Board, RF Driver Mixer [85-131 Screened 605-1225] Add: [4] 85-131-2 [1] PC Board, RF Driver Mixer [85-131 Screened 605-1616] Reason for change: To correct tuning trouble.September 14, 1972 HW-100 Bulletin No: SSB Transceiver HW-100-1 Repeated Heterdodyne Oscillator Tube FailureInadequate USB-LSBFrequency Shift Change: R-212 from 220 ohm to 330 ohm ˝ watt resistor [PN 1-4]. Lack of VFO shift range can be corrected by changing the value of the FET source resistor.Change: R-947 from 470 ohm to 10000 ohm [PN 1-9]. September 14, 1972HW-100 Bulletin No: SSB Transceiver HW-100-2 Diode Leakage in the SB-100/SB-101/HW-100 The silcon diodes used in the SB-100 and SB-101 are standard power diodes rated at 500V PIV and 750ma. For each condition described, the diodes should be replaced with an equal value top maintain proper operation. 1. Diodes D902 and D903, when leaky, will have an effect on ALC indication. The ALC indication will be normal for the first half hour to an hour. Then the meter indication will start dropping off until there is very little indication. 2. D101, when leaky or defective, will cause slow or no receiver recovery after transmitting for any period of time. 3. D905, under leaky conditions, will cause very slow receiver recovery and false meter indications. The meter will kick up scale and slowly drift down to zero. 4. D201 will result in a decrease in VOX sensitivity to the point where the VOX circuit will not be activated. It can also result in increasing VOX delay, causing the relay to stay in the transmit condition.May 23, 1974 HW-100 Bulletin No: SSB Transceiver HW-100-3 Alternate Method of Neutralizing the Final Amplifiers Note: Be sure unit is off and power supply high voltage capacitors are discharged. 1. Disconnect final plates and 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 indication 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 and screen grid.? VTVM and RF probe will be needed. **To remove screen voltage in SB-100, HW-100 and HW-101 disconnect R920 [100 ohm resistor] from buss wire between pins of V8 and V9. In the SB-102 removal of accessory plug is all that’s required. To remove high voltage in SB-100, SB-101 and SB-102 disconnect red wire at lug 4 [in SB-100 lug 3] of terminal strip BK that goes to grommet BL. In HW-100 and HW-101 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 and resistor. May 23, 1974HW-100 Bulletin No: SSB Transceiver HW-100-4 SB & HW Series Audio Preamplifier & VOXCircuit Trouble ShootingGuide 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 1.1VACPin 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, 1974HW-100 Bulletin No: SSB Transceiver HW-100-5 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. December 18, 1974HW-100 Bulletin No: SSB Transceiver HW-100-6 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 have 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. November 15, 1976HW-100 Bulletin No: SSB Transceiver HW-100-7Low Receiver Sensitivity Note: Sensitivity of the unit is worse on the higher frequencies [15] & [10] meters. Cure: Diode D907 may be in backwards or banded backwards.June 5, 1978 HW-100 Bulletin No: SSB Transceiver HW-100-9 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 HW-100 Bulletin No: SSB Transceiver HW-100-10Poor AGC Action Leakage in the 6HS6 [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, 1978HW-100 Bulletin No: SSB Transceiver HW-100-11 100 KHZ Calibrator SpursStrong signals may occur at other than 100 KHZ 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 an oscilloscope. August 3, 1978HW-100 Bulletin No: SSB Transceiver HW-100-12Receiver Recovery Slow ************Bulletin Obsolete--------Refer to Bulletin No: HW-100-20******************July 24, 1978 HW-100 Bulletin No: SSB Transceiver HW-100-13 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, 1978HW-100 Bulletin No: SSB Transceiver HW-100-14 Carrier Nulls With 1C14 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 3, 1978 HW-100 Bulletin No: SSB Transceiver HW-100-15 Relays Chatter In VOX Mode This may occur when the VOX gain is in the near-full CW