- 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.
ah.3.9. SB-101-4: Diode Leakage in the SB-100, SB-101, HW-101
May 23, 1974
SB-101 Bulletin No:SSB Transceiver SB-101-4
The silicon diodes used in the SB100 & SB101 are standard power diodes rated at
500PIV & 750MA. For each condition described, the diodes should be replaced with an
equal value to maintain proper operation.
1. Diodes D902 & 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 or no receiver recovery and
false meter indications. The meter will kick up scale & 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.
ah.3.10. SB-101-5: SB & HW Series Instability & Corrective Information
May 23, 1974
SB-101 Bulletin No: SSB Transceiver SB-101-5
Instability -- Troubleshooting
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 tothe front panel.
SB-101 Service Bulletins Page 170
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