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Drawing of sailor using test equipment.

CHAPTER 19
REMOTE CONTROL SYSTEMS
WHY USE THEM?

Radio transmitters and receivers are sometimes located a considerable distance away from the operator's station.

The CIC-COMBAT INFORMATION CENTER-of an aircraft carrier is a good example of this. At the CIC, the FIGHTER DIRECTOR OFFICER, FDO, is in constant contact with the fighter squadrons, receiving reports from them and giving orders to direct their operations. You won't always find the TBS or TDQ TRANSMITTERS installed in the CIC, and yet the FDO must be able to control the transmitter without leaving his station. REMOTE CONTROL is the answer.

The compartments where the transmitters and receivers are actually installed vary with the class of ship and the modifications that have been made In the basic design of the ship. On a BB or a CV, the transmitters

 
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are usually several decks below. On a DD or a DE, the transmitter and receiver may be on opposite sides of a bulkhead on one of the superstructure decks.

REMOTE CONTROL SYSTEMS not only eliminate the wasted energy of rushing below to start and stop the transmitter each time a message is to be sent, but they also permit the radio equipment to be operated from several control points about the ship.

With REMOTE CONTROL the operator can use either code or voice, can switch from one transmitter or receiver to another, can start, stop, or key the transmitter and can handle a number of other tasks necessary to maintaining communication-all without going near the transmitter room.

NOT ALL of these operations are completely automatic, to be achieved by merely punching a button. Several require the aid of an E TM or another RM to switch the PATCH CORDS on the TRANSFER PANELS, tune the receivers and transmitters, and make several other necessary operating adjustments.

PARTS OF A TYPICAL REMOTE CONTROL SYSTEM

Remote control systems on all Navy ships follow the same general pattern. The systems installed in a BB or CA have many circuits. Those on a DD have the same variety of parts, but not AS MANY pieces of each type of part. This relationship may be compared to the telephone systems in a large city and a small town. Both systems have the same parts-desk sets, switch boards, wires, and the like-but the larger city will have a greater number of each of these parts.

In figure 129, you see a typical REMOTE CONTROL SYSTEM that you will find installed in Navy ships. The circuits handle one transmitter, one receiver, and a remote station. If additional transmitters, receivers, and remote stations are used, the extra units and circuits will be DUPLICATES of these shown.

In addition to the two major units-the TRANSMITTER and the RECEIVER-a remote control system has a number

 
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FOLDOUT-Figure 129.-Typical remote control system.

of other parts. In figure 129, the RECEIVER UNIT is in the lower left-hand corner. A KEY CONTROL PANEL is next to the receiver. From the key panel you can start, stop, and key the transmitter.

A JACK BOX with a receiver OFF-ON switch is connected to the receiver OUTPUT. The box has two outlets so that you can use two sets of headphones.

Another key control panel and jack box is indicated in the upper left-hand corner. This tells you that several of these units may be installed at various stations in the ship.

The TRANSMITTER-VOICE AMPLIFIER-MODULATOR UNIT is in the lower right-hand corner of figure 129.

The FREQUENCY METER between the transmitter and receiver units is used to check the frequency of the transmitter. This check can be made locally or, with some installations, from one of the remote stations.

The upper right hand corner of figure 129 contains a RADIOPHONE UNIT, with the controls necessary for maintaining both VOICE and C.W. COMMUNICATION.

Three TRANSFER PANELS-RECEIVER, TRANSMITTER, and RADIOPHONE-extend across the center section of the illustration. These panels are SWITCH BOARDS, similar to those used with telephone circuits. The E TM or RM who mans these boards can switch from one transmitter or receiver to another by pulling the PATCH CORDS out of one jack and inserting them in another.

CONNECTING CABLES and TERMINAL STRIPS for connecting the cables make up the rest of the remote control system.

KEY CONTROL PANEL

Figure 130 is a top and a sectional view of a KEY CONTROL PANEL. This unit is mounted so that the top of the panel is FLUSH with the top of the operator's desk. Notice that this panel contains the OFF-ON switch and INDICATOR light to show whether the transmitter is turned on or not. With the newer systems all you need to do to

 
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Key control panel.
Figure 130.-Key control panel.
start the transmitter is press the ON button. And pressing the OFF button shuts it down.

RADIOPHONE UNIT

Figure 131 is the front panel of a RADIOPHONE UNIT. The unit is provided with a cover that is water-tight when closed and locked.

The radiophone has a combination microphone-and-receiver, similar to a handset telephone. When not being used, the handset is held in place on the unit by a clamp hook. When you remove the handset from the hook, a switch is closed, just as it is when you pick up the handset of a regular telephone. The "CARRIER-ON" BULB lights up when the handset is removed from the hook, indicating that power is being applied to the handset.

The intensity of sound produced by the earphone is regulated by the knob marked "EARPHONE LEVEL," near the center of the panel.

Two plugs for 5-tip jacks are mounted at the bottom of the panel. These are for use with extension handset or breastset phones.

 
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The KEY CIRCUIT OFF-ON SWITCH is used only when you wish to send a C.W. message instead of a voice message. The KEY is a separate unit and may be installed some distance away from the RADIOPHONE UNIT.

The NOISE SUPPRESSOR is normally ON. This device reduces the level of the audible message, as well as the level of the noise. When the messages are at low-level intensity, you PRESS the button to CUT-OFF the noise suppressor so that the message will be stronger. When you release the button, the noise suppressor is automatically CUT-IN to the circuit.

A water-tight radiophone unit.
Figure 131.-A water-tight radiophone unit.
 
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The POWER START-STOP BUTTON arrangement is just the same as on the key control panel.

JACK BOXES

Two types of JACK BOXES are used with most remote control systems. The type with a switch, identified by number 49029 in figure 129, is shown in figure 132. The other jack, identified in figure 129 by number 49063, is

Jack box with switch.
Figure 132.-Jack box with switch.
shown in figure 133. This type has six jacks, but no switch. It is used in figure 129, to connect the frequency meter to the transmitter.

TRANSFER PANELS

TRANSFER PANELS are sheets of bakelite or some other insulating material equipped with jacks or sockets to receive the PATCH CORD PLUGS.

 
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Shielded jack box.
Figure 133.-Shielded jack box.
The RECEIVER TRANSFER PANEL uses jacks of the type shown in figure 133. At each end of the cords is a plug of the type shown in figure 134.
Two-contact plug.
Figure 134.-Two-contact plug.
If the operator at the radiophone unit, in figure 131, wishes to check the frequency of the transmitter, he will insert one end of the patch cord in jack C and the other end in jack I.
 
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If the operator wishes to cut-in on the receiver, he will plug one end of the patch cord into jack H, the other end into jack C.

The transfer panels for the TRANSMITTER and RADIO-PHONE unit are slightly different from the RECEIVER panel. The SOCKETS resemble vacuum tube sockets. The PLUG is similar to the base of a vacuum tube. The plug is prevented from slipping out of the socket by a COLLAR that fits over the plug and screws tightly to the base.

The spacing and the size of holes in the sockets prevent you from inserting the plug into a socket incorrectly.

THE RELAY

The RELAY is the device that really makes a remote CONTROL system work. You first heard about the relay in BASIC ELECTRICITY. Here is a brief explanation of its principles.

Basic relay circuit.
Figure 135.-Basic relay circuit.
In figure 135 when switch SW is closed, the electromagnet is energized and pulls the armature TOWARD the core of the magnet. When this happens, the contacts on
 
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the armature close the circuit and turn on the light. When the switch is opened, the contacts open and the light goes out.

The relay in figure 135 is a single-contact, single-acting type. In addition to this type, the Navy uses many multiple contact and multiple pole relays. Some are designed to open one circuit and at the same time close another. Others close two and open one.

RELAY CLASSIFICATION

Relays used with Navy radio equipment are divided into three classes-OPERATIVE, PROTECTIVE, and CONTROL-according to their USE. The wide variety of applications is responsible for the many modifications in the basic design of the relay.

RELAY KEYING

Practically all Navy equipment uses a RELAY CIRCUIT to make-and-break the transmitter circuit in forming the dits and dahs of a code message. The use of a KEYING RELAY has two decided advantages-SAFETY, and CONVENIENCE of installation.

The potential used to energize the relay is Low, usually less than 10 volts a.c. or d.c. While a potential of 110 volts is not dangerous IN MOST CASES, relay keying gives assurance to the operator that he can touch any part of the key safely and without receiving a painful shock.

The transmitter usually is located some distance from the operator's desk. If a relay is not used, it is necessary to run the HIGH-VOLTAGE lines a considerable distance to reach the key. But when a relay is used, the high voltages are kept completely inside the transmitter cabinet where they belong, and you avoid the task of installing a high-voltage line.

The use of a relay requires additional equipment, but the convenience of installation, and the safety achieved, more than compensate for the additional expense. Seldom will you find a keying circuit that does not use a relay. The keying relay is an example of the OPERATIVE TYPE of relay.

 
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PROTECTIVE RELAYS

A PROTECTIVE RELAY safeguards a piece of electrical gear from damage that may be caused by excessive current drainage. Some relays are designed to break the circuit INSTANTLY; others have TIME DELAY features that will permit small overloads for short periods of time. Still others are designed to DELAY the TURNING-ON of a high voltage until a certain length of time has elapsed.

The DELAYED ACTION RELAY POSTPONES the CLOSING of a circuit for a certain number of seconds after the operating button is punched. This type of relay is used in starting the transmitters. One of its actions is to defer the turning on of the high voltage until the filaments of the tubes are hot. Its action is not dependent upon the overloading of a circuit, as is true with the inverse-time-delay relay.

CONTROL RELAYS

CONTROL RELAYS are used to START and STOP electric motors. The heavy relay that actually applies the power to the motor is the MAIN LINE CONTACTOR. The relays

Sequence closing relays used with grid and plate circuits.
Figure 136.-Sequence closing relays used with grid and plate circuits.
 
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that control the main line contactors are usually SERIES or SHUNT RELAYS. All of the relay units are referred to collectively as MAGNETIC CONTROLLERS.

SEQUENCE OF CLOSING RELAY SYSTEMS

Many circuits require that the voltages be turned on in the proper order. The grid and plate circuits of a transmitter are examples of this. If the plate potential is turned on before the grid voltage, the tube may be damaged by excessively high current. In figure 136, the potential applied to the grid circuit closes the plate circuit. If anything happens to make the bias voltage fail, the plate circuit will open, preventing damage to the tube.

Without relays, remote control systems would not be possible, and this in turn would greatly add to the task of operating transmitters.

 
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