Adjustments
HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual 7-23
PA adjustments
108-04963 and 08-05237
Driver bias
Adjusting the driver bias
q Disconnect exciter output to the PA by removing the connector from J2 on
the PA and Filter PCB assembly.
q With the transceiver switched off and the DC supply disconnected, unsolder
LINK (DC supply to the driver transistors V21 and V22) next to the black
negative battery lead.
q Connect a multimeter, set to DC 100 mA range, in place of the removed link
(+ positive to the left as viewed from the front).
q Connect the DC supply and switch on the transceiver.
q Select any transmit channel and operate the PTT (Transmit mode). Check
the driver current measures 18 mA ±3 mA.
If the current is out of the specified limit stated above it can be changed by
selecting an alternative SOT resistor R54.
q Switch off the transceiver, disconnect multimeter and replace LINK with a
length of TCW.
PA bias
Adjusting the bias of the output PA transistors
q Disconnect exciter output to the PA by removing the connector from J2 on
the PA and Filter PCB assembly.
q With the transceiver switched off and the DC supply disconnected, unsolder
fuse PA O/P (DC supply to the output transistors V23 and V24) next to the
red positive battery lead.
q Connect a multimeter, set to DC 1 A range, in place of the removed fuse
(positive to the left as viewed from the front).
q Connect the DC supply and switch on the transceiver.
q Select any transmit channel and operate the PTT (Transmit mode). Check
the output transistor current measures 300 mA ±30 mA.
q If the current is out of the specified limits stated above, adjust preset
potentiometer R59 to 300 mA ±30 mA.
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