10. Stage-Gain Measurements
use voltage and resistance measurements
to isolate the trouble to a particular part.
Use the techniques outlined below when
b. Use of Chart. The troubleshooting
the output of the rf amplifiers abnormally
chart is designed to supplement the oper-
low or distorted (item 4 or 5 of the trou-
ational checks detailed in TM 11-6625-
bleshooting chart).
3 5 3 - 1 2 . If previous operational checks
a. Connections. Connect the rf ampli-
have resulted in reference to a particular
fier to a suitable power source and set the
i t e m of this chart, go directly to the
GAIN control to 40 DB. Connect the out-
referenced item. If no operational symp-
p u t terminals of Audio Oscillator TS-
toms are known, begin with item 1 of the
3 8 2 A / U (or equivalent, such as Audio
troubleshooting chart and proceed until a
Oscillator TS-421A/U) to the rf amplifier
symptom of trouble appears.
as indicated in below. Connect the OUT-
PUT terminals of the rf amplifier to the
Caution: If operational symptoms are
I N P U T terminals on Voltmeter, Meter
not known or if they indicate the possibi-
ME-30A/U.
lity of short circuits within the rf ampli-
b. Procedure. Apply a 1,000-cycle sig-
fier, m a k e the short-circuit tests de-
nal from the audio oscillator to the points
scribed in paragraph 7 before applying
indicated in the following table; at each
power to the rf amplifier.
point, adjust the audio oscillator output
at each step to obtain a reading of 1 volt
c. Conditions to Tests. All checks out-
o n the ME-30A/U. Compare the audio
l i n e d in the chart are to be conducted
oscillator output and the computed stage
with the rf amplifier connected to a power
gains (found by dividing the audio oscillator
source as described in TM 11-6625-353-
voltage applied to the plate, by the audio
12.
Figure 6. Rf amplifier chassis, top view.
11
