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Page Title: Retransmission Using RT-505/PRC-25's or RT-841/PRG-77's
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TM 11-5820-498-35
2-7 Retransmission Using RT-505/PRC-25's or
No. 2 go into standby condition as described in
(1) above.
a. Basic Setup. The CX-4656/GRC connection
(7) When radio station No. 4 keys its trans-
between the two receiver-transmitters No. 2 and
mitter and transmits its signals, receiver-trans-
No. 3 at the relay site is shown in note 5, figure
mitters No. 3 and No. 2 perform in the same
4-7. On the receiver-transmitters, the function
manner as described in (2) through (5) above.
pitches are set to RETRANS. The distant radio
(8) When an audio accessory is connected to
stations must be set up for squelch operation in
the audio accessory receptacle on the
order to provide the automatic sending of the
CX-4656/GRC network box, the audio accessory
150-Hz squelch signal when they are keyed for
circuits are effectively connected to the output
transmission. When the relay site receiver-trans-
audio circuits of receiver-transmitter No. 3 (the
mitters are set up for retransmission, the 150-Hz
one next to the choke box of the CX-4656/GRC
squelch signal is used to operate relays for auto-
48 feet away). Accordingly, the audio accessory
matic retransmission and keying of the sending
user can perform the following operations.
(a) Hear the signal being transmitted
b. Circuit Functioning. Under the setup in a
from radio station No. 4 to radio station No. 1.
above, the retransmission circuits perform as
(b) While receiver-transmitter No. 2 is
given in (1) through (8) below.
keyed (by squelch tone from No. 4), the user can
(1) Before a radio signal is received from
talk to radio station No. 1.
either distant radio station, the relay site re-
(c) If the radios are on standby, the user
can key (through pin C) and transmit (through
ceiver-transmitters are in standby mode. Under
pin D) over receiver-transmitter No. 3 to No. 4.
this condition, the audio output transformers in
receiver  a m p l i f i e r s A25/A55 are grounded
The reply from radio station No. 4 will be heard
(through pin B). The action will also cause the
through contacts of squelch relay K1 and func-
reply to be heard at radio station No. 1
tion switch S1. Thus, no audio signals can pass
(d) To transmit to radio station No. 1, the
between the relay site radios.
(2) When a signal, including the 150-Hz
user must transfer the audio accessory to the
AUDIO connector on receiver-transmitter No. 2,
quelch signal, is received at receiver-transmitter
No. 2, it is applied through RF-IF amplifiers and
w h i c h is next to the network box of the
discriminator to receiver audio amplifier
CX-4656/GRC (2 feet away).
2-8. Retransmission Using Receiver-
(3) From the discriminator, the 150/Hz
Transmitters  r Radio RT-246(*)/VRC or
squelch signal is applied to squelch relay control
RT-524(*)/VRC With RT-505/PRC-25
A24/A54. A24/A54 then provides a closed circuit
or RT-841/PRC-77
to operate relay K3. When K3 operates, contact
8-3 remove the short from audio output trans-
RT246(*)/VRC and RT-524(*)/VRC rep-
former in A25/A55 ((1) above).
resent all models of each receiver-transmitter.
(4) Simultaneously, ground on audio output
When the RT-505/PRC-25 or RT-841/PRC-77 is
transformer in A25/A55 is provided through the
connected  to
RT-246(*)/VRC  or
function switch and applied through the diode in
RT-524(*)/VRC for retransmission, the circuit
the CX-4656/GRC, and through receiver-trans-
performance of the radios during retransmission
mitter No. 3 relays K1 and K2 to the battery.
is similar to that described in paragraph 2-7.
Thus, contacts 4-7 of relay K1 provide 10 volts
Refer to figure 4-8 for the following circuit func-
operating power to receiver-transmitter No. 3
tioning descriptions.
transmitting circuits.
a. Basic Setup. The CX-4656/GRC connection
(5) With the transmitting circuits in re-
between receiver-transmitters No. 2 and 3 is
ceiver-transmitter No. 3 in transmit mode, speech
shown in figure 4-5. On receiver-transmitter No.
signals now can be applied from receiver-trans-
2, the function switch is set to RETRANS; on re-
mitter No. 2 through the CX-4656/GRC to re-
ceiver-transmitter No. 3, the SQUELCH switch is
ceiver-transmitter No. 3 speech amplifier A22,
set to NEW ON or OLD ON, depending on the
and through the transmitting amplifier and P.A.
radio station used at radio station No. 4.
stages to the antenna for transmission to radio
b. Circuit Functioning. Under the setup in a
station No. 4.
above, the retransmission circuits function as
(6) When radio station No. 1 ceases keying
given in (1) through (7) below.
its transmitter, receiver-transmitters No. 3 and

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