circuit. The cathodes of V805, V806, V807,
are combined across the center-tapped
and V808 are returned to ground through
primary of output transformer T802.
m e t e r shunt resistor R828. The voltage
b. Plate voltage is supplied from the
drop across resistor R828, caused by
+300-volt dc supply through the center tap
cathode current drawn by the tubes, is ap-
(terminal 4) of the primary winding. On
plied to the meter circuit (para 72) to indi-
receive, the voltage is dropped to approxi-
cate the percentage of modulation (% MOD)
mately +270 volts dc. Screen grid voltage
on transmit. The voltage across the tapped
is supplied from the +125-volt dc supply.
secondary winding of T802 is applied to the
Resistors R845, R846, R847, and R848 are
audio output circuits (para 45).
p a r a s i t i c suppressors in the screen grid
Figure 14. Second receiver audio amplifier V804 and receiver output amplifiers V805, V806, V807, and
V808, schematic diagram.
off terminal 6 of the secondary of
45. Audio Output Circuits
o u t p u t transformer T802 and ap-
plied to the speaker circuits
through contacts 8 and 17 of relay
The audio ouput circuits supply received
K 8 0 2 to the speaker circuits. On
audio signals to the speaker and headset
transmit, contacts 9 and 17, and 11
terminals of the front panel and to Radio
and 19 of relay K802 close. Speaker
Set Control C-1439/U AUDIO jacks. When
audio is tapped off terminal 8 of
R a d i o Set AN/GRC-3 through -8 is used
T802. Resistor R833 decreases the
f o r retransmission purposes, fixed-level
s p e a k e r sidetone audio level ap-
audio can be applied through P1.
proximately 20 decibels (db) with
r e s p e c t to the audio level on re-
a. Speaker Audio.
(1) On receive, speaker audio is tapped