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95307-000-01 6/87
RET-041 Instructions
page 13
2) Extend Card #1F1O.
Remove Card #1F1O, insert a card extender into slot #1 of OPTIMOD-AM ' s card cage,
and then plug Card #1F1O into the extender card.
3) Verify DC voltages.
Measure voltages against circuit ground available at pin C of the edge connector on Card
#1F1O.).
a) Set the MODE switch to OPERATE.
b) Turn the POS PEAK THRESH control fully counterclockwise.
c) Measure the voltage at the anode of diode CR2 on Card #1F1O to verify that it is -4.1
volts DC, ±0.4V.
d) Measure the voltage at the cathode of diode CR1 on Card #1F1O to verify that it is
+4.1 volts DC, ±0.4V.
e) Set the MODE switch to PROOF.
f) Measure the voltage at the anode of diode CR2 on Card #1F1O to verify that it is
approximately -14 volts DC.
g) Measure the voltage at the cathode of diode CR1 on Card #1F1O to verify that it is
approximately +14 volts DC.
4) Verify performance of the 5kHz low-pass filter, and of " bypass " .
In " bypass " , 12kHz low-pass filtering is provided by other OPTIMOD-AM cards.
a) Connect the output of a sweep or tracking generator to OPTIMOD-AM ' s input
b) Connect the input of a spectrum analyzer or oscilloscope to TP2 on Card #1F1O.
c) Place jumpers A night) and B day) on Card #1F1O in the " 12kHz " position.
d) Verify that response is flat ± IdB to 12kHz.
e) Place jumpers A night) and B day) on Card #1F1O in the " 5kHz " position.
f) Verify that response is flat ± IdB to 5.0kHz, and rolls off with a slope of greater than
30dB/octave above 5kHz.
It is normal to see a slight " glitch** at 10kHz about -30dB.
g) Place jumper B day) on Card #1F1O in the " 12kHz " position.
h) Verify that the 5kHz 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 steep rolloff of frequencies higher than
5kHz, as above.
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