TM 11-5820-890-10-3
BASIC COMSEC PROCEDURES
SECURE COMMUNICATION. Secure operations may be done in SC or FH modes. A COMSEC key is a variable used to
enable secure communication. Two radios having the same COMSEC key can communicate in cipher text by setting the
KY57 MODE switch set to C.
NOTE
When a station operating in plain text calls one operating in cipher text , the receiving operator can hear
the message and the beeping in the background. This tells the receiving operator that the sender is
broadcasting in plain text.
LOADING COMSEC KEYS (local fill).
a.
Connect KY57 to RT.
b.
Set KY57 COMSEC to C and register to a numbered position.
c.
Turn KY57 power to ON (COMSEC alarm is heard).
d.
Press handset push to talk button 2 times (COMSEC alarm clears to a steady tone.
e.
Set KY57 MODE to LD.
f.
Connect KYK13 to KY57 using fill cable.
g.
Turn KYK13 to ON and fill register to a numbered position.
h.
Press handset push to talk. A beep is heard and the KYK13 lamp blinks.
i.
Turn KYK13 to OFF and disconnect from KY57.
j.
Set KY57 MODE to C.
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