25. Check to be sure that the PA tune shaft turns the variable capacitor & is not slipping
in the insulated coupling.
ah.2.5. SB-100-5: Oscillations or Low Drive
December 18,1974
SB-100 Bulletin No: SSB Transceiver SB-100-5
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 [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.
ah.2.6. SB-100-6: Self Oscillations Occurring After Installation of Steel Comb
Brackets
May 2, 1975
SB-100 Bulletin No: SSB Transceiver SB-100-6
It has been found that in a number of units, self oscillations are still occurring after
installation of both steel comb brackets [Part No: 204-2096].
To correct the condition, the screws around the RF driver board must be tightened
securely. Also, the lock washers 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.2.7. SB-100-7: S-Meter Drift
March 26, 1976
SB-100 Bulletin No: SSB Transceiver SB-100-7
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.2.8. SB-100-8: Transmitter Oscillates in Transmit with the Mic Keyed
September 27, 1977
SB-100 Bulletin No: SSB Transceiver SB-100-8
SB-100 Service Bulletins Page 165
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