Adjustments
7-30 HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual
Noise limiter operation
q Check the RF gain is off (test channel 20 for 2 to 26.5 MHz PA
[1 08-04963] or test channel 29 for 2.25 to 30 MHz PA [1 08-05237]).
q Set the signal generator frequency 1 kHz above the SCF of the selected
channel (1 kHz below for LSB).
q Connect the output via a tee piece to the antenna socket J1.
q Set the signal generator to 0.4 µV PD.
q Connect a BNC to a two-terminal adaptor. Connect this to the other end of
the tee piece.
q Connect the output of a square-wave generator to the adaptor via a 100 pF
capacitor.
q Set the square-wave generator frequency to a 100 Hz and the output to
5 V PP.
When the noise limiter is on, the signal produced by the signal generator
should be clearly heard over the interfering signal from the square-wave
generator.
q Switch the noise limiter off by shorting A–E on noise limiter test point
TP202 located on the Rx/Exciter PCB [1 08-04962 and 08-05322].
The noise from the square-wave generator should swamp the wanted signal
from the signal generator. This test will verify the noise limiter is
functioning correctly.
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