TM 11-6625-828-45
attached to the front panel, which normally is used to
simultaneous voice and signal transmission. The voice
terminate J105.
modulation is connected through amplifier stage V116B
to modulator V102. Amplifier V116B also functions as
the amplifier for any other external modulation source
meter M102 circuit is a linear voltmeter circuit designed
which may be connected to EXT E102 and MOD E103
to measure the audio voltage derived from the
binding posts, located on the front panel. These binding
modulated RF carrier by cathode follower V11OB in RF
posts are automatically short- circuited when the push-
unit Z104. The demodulated output from Z104 (terminal
to-talk button of a microphone plugged into MIC jack
3) is connected through C162 which acts to remove the
J108 is operated.
dc component present. % M meter M102 is connected
between the cathode circuits of modulation monitor
1,000-cycle oscillator uses V107 as a phase-shift
cathode follower V115A and V115B which detects the
oscillator. Feedback is attained from the plate circuit of
audio voltage of second doubler V109. Initial meter
V107 back to the common connection of C127 and
current is bucked out as explained previously. Under a
C128. When IDENTIFIER switch S104 is at ON, it
condition of no modulation, zero setting of M102 is
grounds V106. Therefore, V106 in parallel. with the
achieved by adjustment of ZERO SET control R218.
plate circuit of V107 illuminates. When MODULATION
When the RF out- put is set at the standard level (the
switch S102 is in position 11 (1,000 cycles), oscillation is
redline indication on RF meter M101), %M meter M102
fed from the grid circuit of V107, through the wiper of
indicates the percent modulation. The sensitivity of
1000- MOD control R163 and the switch to the grid of
M102 is such that with MODULATION switch S102 in
V104B. This signal is then amplified by modulation
either the 9,960- SET or the 30- SET position, the
amplifier by V104B and fed to modulator V102.
LEVEL SET (green arrow) indication corresponds to 30
percent modulation.
w. Microphone and External Modulation Circuit
828-4S TION switch S102, voice modulation may be
superimposed on the internal test modulations to permit
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