ANCILLARY EQUIPMENT

problem with most transceivers, some do have provi- sions for separate transmit and receive operations, al- lowing them to overcome the problem. ANCILLARY EQUIPMENT Now that we have looked at the basic components of a communications system, let’s identify some of the ancillary equipment required to make a transmitter and receiver useful. HANDSET A handset converts acoustical (sound) energy into electrical energy, which is used to modulate a transmit- ter. It also converts electrical energy into acoustical en- ergy for the reproduction of the received signal. To key a transmitter, the push-to-talk button is de- pressed, closing the dc keying circuit, which places the transmitter on the air. The handset is normally con- nected to a radio set control but can be used locally at the transmitter. Using the “local” option is a good way to determine whether a problem exists in the transmit- ter or remote equipment. RADIO SET CONTROL The radio set control provides the capability to control certain transmitter functions and the receiver output from a remote location. Some control units con- tain circuits for turning the transmitter on and off, voice modulating the transmission, keying when using CW, controlling receiver output, and muting the re- ceiver when transmitting. A representative radio set control unit is shown in figure 1-10. As many as four of these units maybe par- alleled to a single transmitter/receiver group to provide additional operating positions. This setup is often found aboard ship when a transmitter or receiver is controlled from various locations like the bridge or combat information center. TRANSMITTER TRANSFER SWITCHBOARD The transmitter transfer switchboard allows the re- mote control station functions and signals to be trans- ferred selectively to the transmitters. Figure 1-11 shows a transfer switchboard that allows the functions and controls of anyone, or all, of 10 remote control sta- tion functions and signals to be transferred selectively to any one of six transmitters. Each knob corresponds Figure 1-10.—Radio set control Figure 1-11.—Transmitter Transfer Switchboard (SB- 988/SRT). to a remote control station and has 8 operating posi- tions. Positions 1 through 6 correspond to attached transmitters. The seventh position (X) allows for switching of the transmitters to another switchboard. The eighth position (OFF) removes the remote from the system. 1-12