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DYNAMIC MEASUREMENTS
DETECTOR AND ACG TEST
Turn the power OFF and connect the VOM and RF
generator as shown in Figure 15.
Set the VOM to accurately read 2 volts DC and set
the output of the RF generator for 455kHz, no
modulation, and minimum amplitude. Turn the power
Amps
TP8
Figure 15
If your RF generator does not have amplitude modulation or you do not have an oscilloscope, go to Section 3.
SYSTEM CHECK
Connect equipment as shown in Figure 16.
Set the RF generator at 455kHz, 1kHz at 80%
modulation and minimum output. Turn the power ON
and put the volume control at full clockwise position.
Oscilloscope
DETECTOR BANDWIDTH TEST
Connect equipment as shown in Figure 16. Set the
RF generator at 455kHz with 80% modulation at a
modulation frequency of 1kHz. Set the oscilloscope
to read .1 volts per division. Turn the power ON and
put the volume control at minimum. Increase the
amplitude of the RF generator until the signal on the
oscilloscope is 4 divisions peak to peak. Check the
signal to make sure it is free of all distortion. Leave
V
COM
V
Probe
TP8
ON and slowly increase the amplitude of the 455kHz
signal from the RF generator until the voltage at TP3
just starts to drop. This point is called the AGC
threshold with no IF gain.
amplitude setting on the RF generator here:
____________. Turn the power OFF.
Slowly adjust the amplitude of the RF generator
output until you hear the 1kHz on the speaker. If this
test fails, turn the power OFF and check C11, R12,
volume control, D1 and TP3.
.02μF
the frequency of the RF output at 455kHz, but
increase the modulation frequency until the output
drops to 0.28 Vpp. Record the modulation frequency
on the RF generator here:
This frequency should be greater than 5kHz. Turn
the power OFF.
-17-
Make a note of the
Generator
TP8
Output
Adjust
.02μF
Generator
Output
TP8
Adjust
Figure 16
____________
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