TM 11-5820-890-10-3
COMSEC KEYS. These are variables needed for cipher text (CT) operation. They are loaded into the KY-57.
LOCAL FILL OF COMSEC KEYS. A COMSEC key is required for CT operation and is loaded into the KY-57 using a
COMSEC fill device.
COMMUNICATING IN AN FH NET: An FH radio net must be opened by the NCS. This synchronizes the net radios; then
normal radio procedures are used for communicating. The procedure used to open a net is called cold start net opening.
OTHER FH OPERATIONS: These include updating FH data by ERF, passive late net entry, and CUE and ERF late net
entry. Late entry is used when you are out of the net for any reason. CUE is used for contacting an FH radio net when you
are not an active member. CUE is also used if you missed your primary net’s opening, or when requesting entry into an
alternate net. CUE may be used if you are operating an SC radio and wish to contact an FH net.
MAINTAINING RADIO’S MEMORY: Memory, or FH fills and SC frequencies, is maintained in two ways. Main power,
either battery or vehicular system, allows radio to retain all memory so long as main power is applied. A hold up battery
(HUB) serves as back up for memory retention. HUB power cuts in automatically if main power is disrupted for any
reason, and the HUB becomes operational when ever the FCTN switch is set to OFF.
CLEARING MEMORY: There are three ways data may be cleared from the radio. SC frequencies are cleared by pressing
FREQ and then CLR. FH data is cleared by setting the FCTN switch to position Z-A and waiting for five seconds. Also,
all memory is cleared by setting the FCTN switch to STW and waiting five seconds.
NOTE
When your radio has a good HUB installed, setting FCTN to OFF causes no loss of memory.
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