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|  (4) Connect Radio Frequency Watt-
average deviation is the bandwidth
in megacycles (determined in d or
meter AN/URM-43A to the rt unit
ANT. jack with a 10-foot length of
e above) divided by 2.
RG-8/U coaxial cable.
Note. Always subtract the smaller deviation from
b. Turn the radio set on and set the vari-
the larger deviation.
Example: If the two recorded frequencies
able autotransformer for 115 (or 230) volts
( d above) are 3.538635 and
ac (AN/TRC-68) or the potentiometer for
3.456647 mc, the deviation (plus)
26.4 volts dc (AN/VRC-24) as indicated on
equals 0.038635 mc, the devia-
the ME-26/U. Allow a 2-hour warmup
tion (minus) equals 0.043353,
time.
and the total bandwidth equals
c. Key the transmitter by connecting a
0.081988 mc. The half band-
lead between the RADIO CONT LINE and
width is 0.081988-2 or 0.040994.
CONT LINE RETURN terminals on the
Therefore: half bandwidth dif-
audio test box. Readjust the input voltage
ference percentage at 6 db =
control to maintain the voltage in b above.
100
(.043353 - .038635)
X
= 11.5 percent
indicated on the AN/URM-43A for the fre-
.040994
quency settings listed in the chart in para-
h. The half-bandwidth difference per-
centages (6 or 60 db) must not exceed 15
not less than 16 watts at any test frequency.
percent.
e. Reduce the input voltage to 103 (207)
volts ac (AN/TRC-68) or 22 volts dc (AN/
VRC-24) with the transmitter keyed.
f. Repeat the procedure given in d above.
a. Make the following connections. Use
The rf power output must be not less than
fig. 118 as a guide.
4 watts.
(1) Connect the input voltage control
(variable autotransformer (AN/
TRC-68) or potentiometer (AN/
a. Connections for Normal Audio Test
VRC-24)) and Multimeter ME-26/
U to the radio set input line.
(1) Connect Audio Oscillator TS-382/
(2) Connect the audio test box 10-pin
U to the dummy microphone input.
connector to either AUDIO recep-
Connect Electronic Voltmeter ME-
tacle on the rt unit front panel.
30B/U across the 150-ohm resistor
(3) Connect the 600-ohm load between
in the dummy microphone (fig. 119,
the SPEAKER and AF OUTPUT
note 2).
RETURN terminals on the audio
test box.
(2) Connect the dummy microphone
If.
bandwidth test setup, block diagram.
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