ah.3.12. SB-101-7: Oscillations or Low Drive
December 18, 1974
SB-101 Bulletin No. SSB Transceiver SB-101-7
Loose boards cause sporadic 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 [Part No: 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.
ah.3.13. SB-101-8: Self Oscillations Occurring After Installation of Steel Comb
Brackets
May 2, 1975
SB-101 Bulletin No. SSB Transceiver SB-101-8
It has been found that in a number of units, self oscillations are still occurring after
installation of both sets of comb brackets [Part No: 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.
ah.3.14. SB-101-9: S-Meter Drift
March 29, 1976
SB-101 Bulletin No:SSB Transceiver SB-101-9
To bring the meter drift to an acceptable level, install the following:
- CHANGE: R107 from 100K Ohm 1/2 Watt to 100K 1 Watt [PN 1-28-1]
This makes the voltage divider string more stable with temperature changes caused by
internal heating.
This change will be made in future production runs.
ah.3.15. SB-101-10: Low Receiver Sensitivity
November 15, 1976
SB-101 Bulletin No: SSB Transceiver SB-101-10
Note: Sensitivity of the unit is worse on the higher frequencies [15] & [10] meters.
Cure: Diode D907 may be in backwards or banded backwards.
SB-101 Service Bulletins Page 173
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