KY-28 Operations


1KY-28 PowerOFF and mode switch set to P
2Code SettingDetermine that a proper code has been set by personnel qualified in voice security equipment. In DCS and in combination with SRS (Simple Radio) this is done through the ground crew communication menu in the DCS communications menu.
3UHF RadioON
4Mode SwitchP
5Power KnobON
6Ground TestIf a ground test of equipment is desired, establish two-way, plain-text radio communications on the plain-voice radio with a suitable remote station and request an equipment check. (In DCS another player is needed)
7Mode SwitchC
8Alarm CheckThe KY-28 will perform an automatic alarm check when the mode switch is set to C and the power knob is set to On. The check will continue for about 2 seconds after power is applied. During this time a steady, unbroken 1200 Hz tone is heard in the headsets. Upon successful completion of the check, the 1200 Hz tone is interrupted at a 2.3 Hz rate.
9Clear Interrupted ToneMomentarily position the microphone button to UHF to clear the interrupted tone. When the microphone button is released, the KY-28 reverts to the standby condition and is ready for either transmission or reception. If the unit fails to pass the alarm check, the steady 1200 Hz tone continues and further cipher operation is inhibited.
10Alarm Check FailureNote: If the KY-28 fails the alarm check, the power knob must be set to OFF and the mode switch to P (plain) to enable conventional UHF communications.
11Transmit Ciphered MessagesTo transmit ciphered messages, position the microphone button to UHF and wait until a momentary tone is heard before voice input. With the power knob set to ON, the momentary tone is delayed 0.5 seconds after pressing the microphone button. During this time, an encryption check is performed and the sync preamble is transmitted to receiving stations. If the encryption check fails, a 1200 Hz tone interrupted at a 2.3 Hz rate is presented in the headsets and cipher transmission is not possible. If the encryption check succeeds, a momentary tone is heard in the headsets.
12Cipher Radio CommunicationsAfter the momentary tone is heard, establish two-way cipher radio communications with a cooperating station and check for readability and signal strength and/or transmit your message. Upon releasing the microphone button, the KY-28 will return to the standby condition. Simultaneous transmission by two or more stations on the same frequency is not possible and may result in garbled messages or loss of synchronization.
13Resume Normal CommunicationsResume normal, non-crypto communications if desired at any time by setting the mode switch to P (plain) again.
14In-Flight CheckNote: The above procedures may be used to perform an in-flight check of the equipment.


1Equipment OperationThe speech security equipment shall be operated as briefed.
2Warning:If ZEROIZE is pressed during flight, ciphered communication is not possible. The code can only be reset (or changed) through the ground crew communications menu after landing.

After Landing

1Zeroize as briefed.
2Power OffOFF