- FCTN (function) switch. Sets RT function; operating positions are: SQ ON, SQ OFF, RXMT, and REM. The FCTN switch has positions which are boxed-in. You must pull knob to turn to these positions. This guards against FCTN switch accidentally being moved to these positions. Pull knob to turn to OFF , STBY, Z-FH
- Off–Turns off all power to the RT, including HUB. Clears all memory after five seconds. Used when radio is taken completely out of action.
- TST (test)-Starts RT self-tests. Circuits tested include ECCM, data, and RT. Displays show results.
- SQ ON (squelch on)-Turns on RT and squelch. Used for communication with similar radios. Prevents rushing noise in handset or loudspeaker.
- SQ OFF (squelch off)-Turns on RT, but not squelch. Used with single channel (SC) communications with radios having different squelch systems. May be helpful when RT is being jammed during single channel operations.
- REM (remote)-Disables RT front panel controls. Used for CM and RCU operation.
- RXMT (retransmit)-Puts RT into retransmit mode. Used for retransmit operations.
- LD (load)-Used for loading SC frequencies, FH data, and COMSEC key data. Used to receive ERF.
Download: Introduction to SINCGARS