TM  1-1520-240-10 3-2-14            3-2-19.  Controls and Functions.  (fig. 3-2-7) CONTROLS/ INDICATOR FUNCTION ZEROIZE Switch (under spring- loaded cover) Momentary contact toggle switch used to clear (ZER- OIZE) any crypto-net variables stored in the TSEC/KY-58. Delay Switch Two position toggle switch; DELAY position used when re- ceived signal is to be retrans- mitted. PLAIN/C/RAD1 Switch Two position rotary switch used to select TSEC/KY-58 op- erating mode. A third position (C/RAD 2) is covered and locked out. PLAIN Permits normal (unsecured) communications on associated FM radio set. C/RAD1 Permits secured communica- tions on associated FM radio set. FILL Switch Six position, rotary switch, used to select any of six stor- age registers for storage of crypto-net variable (CNV). MODE Switch Three position rotary switch used to select the operating/ loading mode of the TSEC/ KY-58. OP Allows normal operation of KY-58. LD Allows normal loading of CNV. RV Allows remote loading of CNV. POWER ON Switch Position Two position toggle switch used to apply power to TSEC/ KY-58. 3-2-20.  Normal Operation. a.  Operating procedures for secure voice. NOTE To  talk  in  secure  voice,  the KY-58  must  be loaded with any number of desired variables. (1) Set the MODE switch to OP. (2) Set the FILL switch to the storage register which contains the required CNV. Figure  3-2-7.  Remote Control Unit TSEC/KY-58 (Z-AHP) (3) Pull out and lift up the POWER switch to ON. A beeping tone and background noise will be heard in the headset. Before the set can be used, the tone must be cleared by momentarily keying the No. 1 VHF AM/FM radio with the PTT switch. (4) Set the PLAIN C/RAD1 switch to C/RAD1. (5) If the signal is to be retransmitted, pull out and lift up the DELAY switch to (ON). (6) Clear voice procedures: To operate in clear voice (plain text) simply: (a) Set     the     PLAIN-C/RAD     switch     to PLAIN. (b) Operate the equipment. b.  Zeroizing procedures. NOTE Instructions should originate from the net con- troller or commander as to when to zeroize the equipment. (1) Lift the red ZEROIZE switch cover. (2) Push  the  spring-loaded  ZEROIZE  switch up. This will zeroize position 1-16. (3) Close the red cover. The equipment is now zeroized and secure voice communications are no lon- ger possible. c.  Automatic remoter keying procedures. NOTE Automatic remote keying (AK) causes an old CNV to be replaced by a new CNV. Net con- troller simply transmits the new CNV over the air to your KY-58. (1) The  net  controller  will  use  a  secure  voice channel, with directions to stand by for an AK transmis- sion. Calls should not be made during this stand-by ac- tion.