Retransmission Using RT-505/PRC-25's or RT-841/PRG-77's

TM 11-5820-498-35

2-7 Retransmission Using RT-505/PRC-25's or

No. 2 go into standby condition as described in

RT-841/PRG-77's

(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.

receiver-transmitter.

(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).

A25/A55.

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

NOTE

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

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

2-9