The KY-57 is the primary piece of VINSON COMSEC equipment used today for voice/data encryption on VHF radios and for a large number of wireline devices. When hooked to a radio, a teletype piece of gear, or a telephone device, the KY-57 can scramble (encrypt) the information being passed through it so only stations on our net having the same key as we do receive the information. The KY-57 uses electronic keys to encrypt the information, can be rekeyed remotely, and can accept signal fades up to 12 seconds without losing synchronization with the transmitting station. The KY-57 can be set up in the man-pack, vehicular, or fixed-site configuration.

TA-312/PT TELEPHONE

The TA-312/PT telephone set shown in figure 11-15 is a lightweight, waterproof, battery-powered, field telephone designed for local-battery or common-battery circuits. It has facilities for operating push-to-talk radio circuits and a range of 14 to 22 miles. The set weighs about 9 1/2 pounds.

The TA-312/PT consists of three primary components.

1. The telephone set case, made of reinforced canvas.

2. The panel and housing assembly that encloses all electrical components.

Figure 11-16.-TA-1/PT telephone set.

3. A transmitter, a receiver with a push-to-talk switch, and a retractable cord. The power supply for the transmitter consists of two dry-cell (BA-30) batteries in series furnishing 3 volts for local battery (LB) operation. The batteries are used on both local-battery and common-battery signaling (CBS) circuits. One battery is installed in the battery compartment with the positive end up; the other with the positive end down. After you install the batteries, close the battery compartment cover and fasten the cover latch. An external, 3-volt battery source maybe used in place of the two BA-30s. Connect the back from the external batteries to the BAT binding posts on the panel. No batteries are required for common-battery operation. In order to operate the TA-312 with the handset, follow the instructions listed below.

1. Put the EXT-INT SWITCH in the INT position.

2. To place a call in LB operation, leave the handset in the retaining brackets and turn the generator hand crank. Remove the handset from the brackets and listen for the party you are calling to answer.

3. To place a call in CB operation, remove the handset from the retaining brackets and listen for the operator to answer.

4. To talk and listen in CBS operation, push in on the press-to-talk switch when you talk release it when you listen.

5. To talk and listen in CB operation, you do not operate the press-to-talk switch.

6. To adjust the buzzer volume, request a distant party to signal; then place the handset in the brackets. When a signal is received, rotate the buzzer control for desired volume.

7. To complete the call, place the handset in the retaining brackets. When the set is connected through an LB switchboard, ring off by turning the hand crank.