Service Manual Part 1
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In this Section, deviation settings are given first for wide band, followed by settings for
medium band in brackets ( ) and settings for narrow band in square brackets [ ].
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Connect an oscilloscope to monitor the waveform at TSP901 (TCXO PCB).
Plug the microphone test lead into the control head microphone input socket.
Apply a 1kHz sine wave.
Slowly increase the sine wave output level until the waveform begins to distort
(squaring), indicating that limiting has commenced.
Any further increase in sine wave output level should not increase the amplitude
of the waveform.
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Connect an oscilloscope to monitor the waveform at TP606 (logic PCB).
Apply a 1kHz sine wave.
Connect an EVM to the junction of R667 and C639.
Increase the sine wave output level to 10dB above the limiting level, as described
in Section 4.5.1.1.
Note the amplitude on the oscilloscope, then increase the output level by another
10dB.
Check that the amplitude of the waveform does not increase or distort signifi-
cantly.
The EVM should show a positive DC reading.