Adjustments
HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual 7-27
q Set up the spectrum analyser as follows:
Centre frequency
Set to frequency of the selected test
channel
Frequency span
20 kHz (2 kHz per division)
Vertical level
10 dB/div
Video bandwidth
300 Hz
Sensitivity
Depends on the signal level applied to the
analyser and will require adjusting when
transmitting
q Select PTT (Transmit mode) and adjust the two tones for compression.
If the compression level is unknown, use an oscilloscope to check the output
of the microphone amplifier at test point TX–AF [1 08-04966]. Adjust the
output for a signal level of 500 mV PP.
q Adjust the two tones displayed on the spectrum analyser for equal amplitude
by operating the balance control on the two-tone signal generator.
q Adjust the sensitivity control on the spectrum analyser to set the two tones at
the top of the screen.
q Measure the intermodulation distortion levels at 2.5 MHz with respect to
each tone. Add 6 dB to the reading if referenced to PEP (refer to transmit
specifications for limits).
q Check the intermodulation distortion on the remaining frequencies including
the 27 MHz channel for the 9323 (see Table 7-4). The centre frequency of
the spectrum analyser must be set to the channel frequency selected.
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To check for spurious and harmonic components during the IMD checks,
adjust the frequency span of the spectrum analyser.
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