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.
ah.2.4. SB-100-4: SB & HW Series Instability and Corrective Information
May 23, 1974
SB-100 Bulletin No: SSB Transceiver SB-100-4
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.
SB-100 Service Bulletins Page 163
To Next Page
Loading...
Need help?
General
