Stage Analysis of Local Control Unit C-2329(*)/GRA-39

TM 11-5820-477-30

(2) Receiving. Signals from the radio set receiver are applied through switch S102, relay K101, filter FL101,

and audio line transformer T101 to the LINE binding post. From here the signals are coupled to the remote

control unit over the connecting field wire. Signals from the receiver are also applied through S102 to the local

control unit operator's earpiece.

d. Sidetone. During telephone communication (para. 1-15a.(2)) or transmission of voice signals through the

radio set (para 1-15b.(1)), a sidetone signal developed in the H-138/U microphone is applied to the H-138/U

earpiece.

(1) TEL position. Voice signals developed in the H-138/U microphone are applied through the preamplifier

(Q101 and Q102), T101, and S102 to the H-138/U earpiece.

(2) RADIO position. Voice signals developed in the H-138/U microphone are applied through S102,T102,

and FL104 to the radio set. Sidetone developed in the radio set is applied through S101 to the H-138/U earpiece.

e. Power Supply. The chart below lists the circuits energized when the TEL-REMOTE-RADIO switch is in the

p o s i t i o n indicated.

S102 Position

Circuit Energized

REMOTE

Preamplifier (Q101, Q102).

Resonant relay amplifier (0103, Q104, Q105).

RADIO

Relay K1O1.

TEL

Preamplifier (Q101, Q102).

I-

I 6. Stage Analysis of Local Control Unit C-2329(*)/GRA-39 (figures FO-5 through FO-8)

NOTE

The following discussion applies to all models of Control, Radio Set C-2329(*)/GRA-39,

except where noted.

Refer to schematic diagrams FO-5, FO-6 FO-7 and FO-8 for minor differences between

models.

The setting of the TEL-REMOTE-RADIO switch determines the distribution of battery

voltage to the stages in paragraphs a. through c. below. This action is described in

a. Prearnplifier (0101 and Q102). The local control unit prearnplifier is functionally the same as the

preamplifier (Q201, Q202) in the remote control unit. For explanation of the circuit and component functions, see

b. Resonant Relay Arnplifier (Q103, (Q104, and Q105). The resonant relay amplifier consists of 3,900-Hz

amplifier Q105 and two emitter followers Q103 and Q104. Emitter followers 0103 and Q104 rectify the output of

3,900-Hz amplifier Q105.

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