Advertisement
95307-000-01 6/87
RET-041 Instructions
page 15
d) Disconnect the audio oscillator and voltmeter from OPTIMOD-AM.
8) Verify 10kHz low-pass filter performance.
a) Connect the output of the sweep or tracking generator to OPTIMOD-AM ' s input.
b) Connect the input of the spectrum analyzer or oscilloscope to TP2.
c) Verify that response is flat +0.5dB, -2.0dB to 9600Hz, and rolls off with a slope of
greater than 60dB/octave above 10kHz.
d) Place jumper B day) on Card #1F1O in the " 12kHz " position.
e) Verify that the 10kHz low-pass filter is activated when the TX EQ DAY/NIGHT switch is
moved to the NIGHT position.
If the filter is operating, you will see a very steep rolloff of frequencies higher
than 10kHz.
f) Verify that the 10kHz low-pass filter is deactivated when the Tk EQ DAY/NIGHT switch
is moved to the DAY position.
If the filter is inactive, you will not see a steep rolloff above 10kHz.
g) On Card #1F1O, place jumper A night) in the " 12kHz " position, and jumper B day)
in the " 10kHz " position.
h) Verify that the 10kHz low-pass filter is activated when the TX EQ DAY/NIGHT switch is
moved to the DAY position.
i) Verify that the 10kHz low-pass filter is deactivated when the TX EQ DAY/NIGHT switch
is moved to the NIGHT position.
j) Disconnect the sweep or tracking generator and spectrum analyzer or oscilloscope from
OPTIMOD-AM.
) Verify distortion performance.
a) Place jumper B day) on Card #1F1O in the " 5kHz " position.
b) Connect the input of a THD analyzer to TP2.
C) Set the TX EQ DAY/NIGHT switch to DAY.
d) Verify that distortion is less than 0.2% with the audio oscillator set for 100Hz, 1.0kHz,
and 4.0kHz in a 20-20, 000Hz bandwidth.
e) Set the TX EQ DAY/NIGHT switch to NIGHT.
f) Verify that distortion is less than 0.2% with the audio oscillator set for 100Hz, 1.0kHz,
5.0kHz, and 10.0kHz in a 20-20, 000Hz bandwidth.
g) Place jumper A night) on Card #1F1O in the " 10kHz " position.
h) Verify that distortion is less than 0.2% with the audio oscillator set for 100Hz, 1.0kHz,
5.0kHz, and 9.0kHz in a 20-20, 000Hz bandwidth.
Advertisement
