TA-312/PT

The TA-312/PT and the TA-43/PT are two-wire, battery-operated field telephones. They may be used in a point-to-point wire system or in any two-wire ring-down subscriber position of a telephone communications system. The Handset H-60 contains a push-to-talk switch which connects power for talking. The TA-312/PT has a built-in Receptacle Connector U-79/U for use with a headset and an associated EXT-INT switch; the TA-43/PT does not. The TA-43/PT was replaced by the TA-312/PT. The TA-955/PT dual tone multi frequency (DTMF) adapter allows push button operational interface with automatic analog switches and regular civilian type phone systems.

Differences Between TA-312 and TA-312A

Case on the "A" is made from a composite material, and the TA-312 is metallic
The handset retaining spring on the "A" is a locking mechanism, you need to push the handset upward to release it. The regular TA-312 has a simple spring.
The "A" version has recessed areas around the battery lock and the EXT-INT switch.
The "A" version has screws to retain the hinges
The ID plates on the "A" is horizontal, where the standard version is vertical.

Technical Characteristics

Range

Wet

Approximately 22.5km(14mi) on WD-1/TT (36 dB working limit)

Dry

Approximately 36.4 km (22 mi) on WD-1/TT (36 dB working limit)

Type of Operation

Common Battery

Voice transmission and signaling power supplied by switchboard

Local Battery

Voice transmission power supplied by two BA-30s, signaling power supplied by a hand-crank generator

Common-Battery Signaling

Signaling power supplied by switchboard, voice transmission provided by two BA-30s

Signaling (Outgoing)

Hand generated, 90 to 100VAC, 20Hz

Signaling (Incoming)

Audible tone, adjustable volume

Controls and Indicators

Hook Switch

Connects H-60PT to line during operation. Switch is operated when H-60/PT is removed from retaining cradle and is open when H-60PT is in retaining cradle.

Selector Switch

Connects internal circuits of TA-312/PT for particular type of service to be used:

Position

CB

Common battery operation, power comes from the switchboard

LB

Local battery operation, power is from the local installed batteries

CBS

Common battery signaling (local battery for voice), power from switch board, but the installed batteries are used for voice. this is useful if the sound quality is low due to long distance from the switchboard.

EXT-INT Switch

Permits selection of H-144(*)/U in place of H-60/PT:

EXT

Selects H-144(*)/U (H-60/PT inoperative).

INT

Selects H-60/PT (H-144(*)/U inoperative).

LOW-LOUD: Adjusts BZ-23/PT (ringer) Volume
HandCrank (part of G-4WPT): When turned, operates G-42A/PT for signaling in LB operation.

Operation

Connect WD-1/TT wire or other to the terminal posts of each phone. It doesnt matter which post, there is no polarity/
Install 2 "D" size batteries
Set the Selector switch to LB (Local Battery) mode
Turn side crank several times quickly to ring the other phone.
lift handset to listen for an answer. In the TA-312 simply lift up on the handset, in the TA-312A, you need to push the handset up to release it from the cradle.
press button on handset to talk. you should hear a sidetone (hear yourself in the speaker) when you talk.
release handset button to allow the other person to talk.
when the call is completed, hang up the phone. You should keep the phone in the cradle when not in use, this will keep the batteries from draining. If the handset is not fully seated anyone on the other side can still hear your conversations via the sound powered function.

Emergency Sound Power Operation

If no battery supply is available, it is possible to transmit for approximately 4 miles by using the receiver (ear speaker, not the microphone) element as a sound-powered transmitter element.