TM 55-1510-221-10
Figure 3-4. VHF-AM Control Panel (VHF-20B)
(2.) Receiver operating procedure:
1.
Transmitter-interphone
selector
switch (audio control panel, fig.
3-1) - No.1 position, or radio
monitor control No.1 -ON.
2. Frequency selector - Set desired
frequency.
3.
Volume control - As required.
(3.)
Transmitter operating procedure:
1.
Transmitter-inter-phone selector
switch (audio control panel, fig.
3-1) - No.1 position.
2.
Microphone switch - Press.
(4.) Shutdown procedure: Volume control
- Turn counterclockwise (OFF).
d.
VHF-AM Set Emergency Operation.
NOTE
Transmission on emergency frequency
(121.500 MHz) is restricted to emergen-
cies only. Emergency frequency 243.000
MHz (guard channel) is also available on
the UHF command radio.
1.
Transmitter-interphone
selector
switch (audio control panel, fig.
3-1) - No. 1 position.
2. Frequency selector (VHF control
panel, fig. 3-4) -121.500 MHz
(emergency frequency).
3. Microphone switch - Press.
3-11. VHF AM-FM COMMAND SET (AN/ARC-
199).
a. Description. The VHF AM-FM Command
Set provides for normal and secure 2-way AM voice
communication in the very high frequency range of
116.000 to 151.975 MHz and FM voice communica-
tion in the 30.000 to 87.975 MHz band. Twenty
channels may be preset. Audio signals are applied
through the No.2 position of the transmitter-
interphone selector switches and through the No.2
receiver audio switches on the pilot’s and copilot’s
audio control panels (fig. 3-1). Complete provisions
only are installed for a TSEC/KY-28 voice security
device. Circuits are protected by a lo-ampere VHF
AM-FM circuit breaker on the overhead circuit
breaker panel (fig. 2-26). Figure 3-5 illustrates the
VHF AM-FM control panel. The associated antenna
is shown in figure 2-1.
3-9
