Audio-Frequency Amplifiers

changer, and pull it out on its slides until it locks in

(CCTV) is receiving wide use throughout the Navy.

place.

So broad are the applications of television that a

special enlisted code is assigned to the IC Electricians

who maintain these systems.

Audio-Frequency Amplifiers

The two audio-frequency (AF) amplifiers are

BLACK-AND-WHITE TV

located in drawers directly below the phonograph

record changer. The upper amplifier is used for

In comparing CCTV with commercial television,

channels 1 and 2, and the lower amplifier is used for

you will notice how nearly alike they are in operation.

channels 3 and 4. A power switch is located on the

The major difference is the methods of transmitting

front of each amplifier drawer.

the picture and sound. In CCTV, several methods of

transmission are used to bring the signals from the

camera to the receiver/monitor. These units may be

OPERATING TIPS

physically connected using telephone or coaxial

cables for short distances. For greater distances, or

When the ship's entertainment system is

when numerous receivers/monitors are involved,

operating, the following procedures should be

transmission is normally accomplished through the

followed:

same media as commercial transmission. This may be

accomplished by using a standard transmitter on

Never permit a program to peak into the red

specially assigned frequencies. When a receiver is

area of the volume output meter unnecessarily.

used, the receiver is generally a standard television

Monitor the output levels of all four channels

receiver. The monitor is basically the same as the

frequently. An increase could overload the am-

television receiver except that the set does not use a

plifier and cause damage. A decrease could be

tuner or associated circuits.

caused by a short circuit or an amplifier mal-

function.

TELEVISED INFORMATION

Monitor each program source routinely for dis-

To understand how a TV system works, you must

tortion.

know what information is passed from the camera to

the receiver. There are four basic kinds of information

Never permit a tape to run out unexpectedly, a

required:

needle to stick in a record groove, or distorted

sound to be broadcast.

Video signal--This signal is the actual moment-

to-moment information that tells the receiving set how

Keep tape recorder/reproducer tape heads and

light or dark each little spot in the picture should be.

guides clean.

Unlike movies, in which an entire picture is flashed

upon the screen every 1/24th of a second, TV pictures

Keep phonograph needle and stylus clean, and

are built up, line by line (525 horizontal lines per

play only clean unscratched records.

picture) and spot by spot within each line (approxi-

mately 426 spots per line). In TV, 30 complete pictures

SHIP'S ENTERTAINMENT

are produced every second.

LOUDSPEAKERS

Blanking signals--These signals tell the camera

and the receiving set when no video signal should be

The type of loudspeaker used with the ship's

present (such as between the end of one line and the

entertainment system are the permanent-magnet,

beginning of the next).

direct-radiator type. Each loudspeaker contains a

volume control switch and a channel selector switch.

Sync signals--Sync (synchronizing) signals are

required to tell the receiving set exactly when to begin

each picture (vertical sync) and when to begin each line

CLOSED-CIRCUIT TELEVISION

within that picture (horizontal sync).

Audio signals--The audio is the sound, or

Television is a rapidly advancing area where IC

Electricians are used. Closed-circuit television

audible, portion of the total TV presentation.

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