Adjustments
7-28 HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual
Receiver performance checks
Sensitivity and (S+N)/N ratio
q Connect an AC voltmeter across the audio output (loudspeaker).
q Select RF gain on test channel 3.
q Set the signal generator frequency 1 kHz above the SCF of the selected
channel (1 kHz below for LSB).
q Connect the output, set to 0.15 µV PD (−123 dBm), to the antenna
socket J1.
q Adjust the volume control for a suitable near full scale dB reading on the
AC voltmeter. Take note of the reading.
q Switch off or adjust the signal generator output to a frequency outside the
receiver band-pass. Check that the audio output drops by at least 10 dB.
q Repeat the above test with the RF gain 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]) and with the signal generator output set to 0.4 µV PD
(-115 dBm).
q Check the audio output drops by at least 10 dB when the signal generator is
switched off or tuned out of the band-pass.
AGC check
q Set up the equipment as for the sensitivity test (see page 7-28, Sensitivity
and (S+N)/N ratio) but with the signal generator output set to 50 mV PD
(-13 dBm).
q Adjust the volume control for a suitable, near full-scale dB reading on the
AC voltmeter.
q Take note of the reading.
q Reduce the signal generator output until the receiver output drops by 6 dB.
The signal generator level should be less than 2.5 µV PD (−99 dBm).
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