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RET-041 Instructions
95307-000-01 6/87
i) Verify that the 5kHz low-pass filter is deactivated when the TX EQ
day
/
night
switch
is moved to the DAY position.
If the filter is inactive, you will not see a steep rolloff above 5kHz.
j) On Card #1F1O, place jumper A night) in the " 12kHz " position, and jumper B day)
in the " 5kHz " position.
k) Verify that the 5kHz low-pass filter is activated when the TX EQ
day
/
night
switch is
moved to the DAY position.
1) Verify that the 5kHz low-pass filter is deactivated when the TX EQ DAY/NIGHT switch
is moved to the NIGHT position.
m) Disconnect the sweep or tracking generator and spectrum analyzer or oscilloscope from
OPTIMOD-AM.
5) Check DC servo operation.
a) Place jumper A night) and B day) on Card #1F1O in the " 10kHz " position.
b) With a digital voltmeter, verify that the DC offset is less than 15mV at TP2.
6) Adjust 10kHz low-pass filter gain.
a) On Card #1F1O, place jumper _B day) in the " 12kHz " position.
b) Connect an audio oscillator to OPTIMOD-AM ' s input
c) Set OPTIMOD-AM ' s VU meter selector to L AGC.
d) Set the audio oscillator to 1kHz, and adjust its output level until OPTIMOD-AM*s VU
meter reads approximately " -6VU " .
e) Set OPTIMOD-AM ' s TX EQ DAY/NIGHT switch to DAY.
f) Observe the level at TP2. Make a note of it
g) Move the TX EQ DAY/NIGHT switch to the NIGHT position.
h) Adjust trimmer R62 until the level at TP2 is the same ±0.1dB) as that observed in
step f, above.
7) Adjust frequency of the first 10kHz low-pass filter ' s notch.
a) Place jumper B day) on Card #1F1O in the " 10kHz " position.
b) Set the audio oscillator for 10,100Hz ±10Hz, and check the frequency with a counter.
The audio oscillator should still be connected to OPTIMOD-AM ' s input Do not
change the audio oscillator ' s output level.
c) While observing TP2 with an audio voltmeter, adjust trimmer R17 to null the signal.
The null should be more than 45dB below the input signal level.
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