e. The RT-1209/URC is the receiver-exciter in the AN/GRC-193A. It is used in
AN/PRC-104A as well as AN/GRC-213 IHFR radio sets (Figure 4). The RT-1209/URC is a
lightweight, compact RT.
It provides 250 milliwatts (mW) of RF from 2 megahertz
(MHz) to 29.9999 MHz in 100-hertz (Hz) steps providing 280,000 distinct
frequencies. It is a single sideband RT with selectable upper or lower sideband.
It has a MODE switch providing voice receive, voice receive and transmit, data
receive, and data receive and transmit.
.It-also has a VOLUME control labeled
OFF/MAX, a push-button switch labeled LIGHT that turns on a lamp inside the
frequency windows, and six one-way push-button switches for setting frequency. The
frequency switches are one way only. Once the number you want passes the window,
you must continue pressing the switch until the proper number rotates back into the
window from 00.0000 MHz to 29.9999 MHz in 100-Hz steps. There are two audio jacks
on the face of the RT and an AlJ1 interface multipin connector on the side, which
connects to the AM-6879.
f. The AM-6879 amplifier-converter has three switches--Sl is the speaker TTY
switch, S2/R1 is the squelch control switch, and S3 is the TTY loop current switch
(Figure 5). TP1 and TP2 are test points to adjust loop current with the R2. E1
and E2 are TTY key connections, and E3 and E4 are TTY loop connections. LS1 is a
built-in loudspeaker, and Fl is a 3-amp fuse that has a spare in the unused fuse
holder in the back. It has a J1 audio jack and a J2 audio jack, which is a six-pin
jack to accept security equipment input.