Ringing Circuit.

TM 11-5820-489-20

TO 31R4-2GRA6-32

Simplified block diagrams and a general description of the Control Group circuits are used to

show the interrelation of the Control Group and radio set operation. This information will also be

helpful when troubleshooting the equipment.

A. Ringing Circuit.

q A hand-cranked, 20-cycle ringing generator is used as the ringing signal transmitting

device.

q The ringing signal is transmitted over a two-wire telephone line between the local and

remote units. A bell and lamp are used as ringing signal receivers.

q A signal switch is used to select the type of ringing signal to be received (audible or

visual).

q The operator of either the local or remote unit can send a ringing signal to the distant

operator.

q The ringing signal has no relationship with the radio set connected to the local control

unit.

B. Telephone Circuit.

q Each of the two control units provides a line transformer with microphone input, receiver

output, and balanced 600-ohm line windings.

q When the transformers are connected by a two-wire telephone line (WD-1/TT), they make

up the basic telephone circuit.

q Installation of two dry cell batteries (BA-30) in each unit, and connection of a Handset

(H-33(*)/PT) to the AUDIO connector of each unit, allows two-way telephone communica-

tion between the local and remote operations.

C. Control Circuit.

q Used to operate push-to-talk capabilities of one or two radio sets (SET 1 and/or SET 2) from

a local or remote position.

q Type of radio set control and mode of operation depend upon the settings of the control

switches at each of the two units. See Operator's Manual TM 11-5820-489-10.

q In some instances, the control circuit is used to control ON/OFF power of the radio set.

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