DISTRIBUTION OF +16 VDC

TM 11-5820-670-30

1-58. RECEIVER-TRANSMITTER INTRAUNIT CIRCUIT FUNCTIONING. (CONT)

In transmit operation, relay K9601 couples regulated +24 vdc through contacts 2 and 6 and contacts 1

and 5 to the rf control modules and rf amplifier. Application of +24 vdc to the rf control through

connector P4501 pin 4, causes the communications antenna to be removed from the receiver input

and connected to the output of band

and band

harmonic filters. Regulated +24 vdc applied to

the rf amplifier activates the amplifier during transmit operation.

DISTRIBUTION OF +16 VDC

Voltage regulator assembly A2100 supplies +16 vdc to the receiver-transmitter. The voltage is

supplied through connector P2101, pin 6 to P3001 pin c on crs A3000, contact 2 on if attenuator

A4900, P5501 pin 7 on receiver-audio amplifier A5500, and to P4501 pin 15 on rf control module

A4500. The +16 vdc is also applied to TEST SWITCH S9601 on the main chassis for metering and to rf

oscillator module A2000 through connector P2001. The vhf tuner receives + 16 vdc through contact 4.

When the radio set is in receive condition, relays K9601, K9603, and K9605 are deenergized, relay

K9605 applies + 16 vdc through contacts 2 and 4 to connector P4001, pin H to activate the circuits in if.

amplifier assembly A4000. Relay K9605 becomes energized only when the radio set is tuning and then

applies + 16 vdc through contacts 5 and 2 to connector P5501 pin 19 on receiver-audio amplifier

assembly A5500. This action turns on the 800 Hz oscillator within the receiver audio amplifier. The 800

Hz tuning tone is applied to the audio line and operator's headset.

During the tuning operation, the voltage regulator assembly applies +16 vdc through connector

P2101, pin 8 to P3001, pin F of crs A3000. This action disables the crs error signal and prevents it

from being applied to receiver local oscillator A1500 when the radio set is tuning.

In transmit operation, relays K9601 and K9603 are energized. Relay K9603 connects +16 vdc output of

voltage regulator assembly A2100 through contacts 5 and 2 to amplifier modulator A8700, oscillator-

buffer A6000, isolation amplifier A6600, and vhf tuner A1000. The power oscillator circuit within the

vhf tuner supplies higher level dc voltages that are used by the tuner.

During homing operation, + 27.5 vdc is applied from the control unit through pin 16 of main power con-

nector P9601 to pin 12 of P4501 on rf control assembly A4500. The + 27.5 vdc homer operate voltage

energizes relay K4502 in the rf control assembly which, in turn, applies + 16 vdc through P4501 pin 6 to

homer amplifier detector assembly A4800 through pin 6 of connector P4801. This voltage activates the

homer detector amplifier.

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