4. Number 2 key Press to delete
the selected channel.
(3) Shutdown Procedure.
1. On/off knob Press. The off page will
appear and flash to warn the operator
that the system is turning off.
2. After 4 seconds, the system will turn
3A-8. VHF COMMUNICATIONS TRANSCEIVER.
Refer to Chapter 3, Paragraph 3-4.
3A-9. HF COMMUNICATIONS TRANSCEIVER.
Refer to Chapter 3, Paragraph 3-3.
3A-10. AIRBORNE TELEPHONE SYSTEM.
The airborne telephone system consists of a
remote transceiver, a telephone base and handset
located in the passenger compartment, and an
The transceiver operates in the UHF band at
frequencies of 454.675 to 454.975 MHz (receiver
(transmitter section). Transmitter power output is a
nominal 10 watts. The maximum operating altitude is
a nominal 51,000 feet. Although the theoretical
maximum range at 31,000 feet altitude is 220 nautical
miles, the range is essentially limited to line-of-sight,
and may be reduced depending upon the altitude of
the aircraft, weather, type of terrain, and the location
and altitude of the ground transmitter. The system is
protected by a 5-ampere RADIO PHONE circuit
breaker located on the right sidewall circuit breaker
panel, Figure 2-6.
Indicators, and Functions. Refer to Figure 3A-4.
(1) Telephone Base Unit. The following
items are located on the telephone base unit.
(a) Hookswitch When pressed by
placing handset in cradle, puts system in standby
mode and deactivates transmitter.
(b) Intercom Lamp (IC) While handset
is in cradle, illuminates to indicate power is on. When
handset is removed from cradle, illuminates to indicate
system is in intercom mode.
Illuminates to indicate an Air/Ground Radiotelephone
Automated Service (AGRAS) station with direct dial
service has been selected.
(d) HF / BELL OFF / PHONE Switch
Selects between HF and PHONE modes. Center
position selects ringer ON or OFF.
(e) Transmit Lamp (TX). Illuminates to
indicate transmitter is activated.
(2) Telephone Handset. The following items
are located on the telephone handset.
(a) PTT Switch When system is in HF
mode, it functions as a push-to-talk/release-to-receive
switch. When the handset is in cradle, it functions as a
release button to unlock handset from base unit.
(b) Numerical Keys Press to select
channels and telephone numbers.
(c) Enter (#) Key When pressed,
immediately enters a channel number or telephone
(d) Clear (Q ) Key When pressed,
clears input in progress without entering.
(e) Hookswitch When pressed, puts
system in standby mode and deactivates transmitter.
(f) Volume Control Rotates to adjust
volume of handset speaker.
b. Airborne Telephone System Operation.
The airborne telephone system may be used either in
HF mode or in PHONE mode. The HF mode permits
the handset to be used as a microphone/speaker in
conjunction with the aircraft's HF communications set
to provide standard two-way radio communications in
(12 telephone channels plus 1 ground-to-air calling
Telephone calls may be placed either with
assistance from an operator at a manned ground
station or direct dialed through AGRAS stations.
When the handset is removed from the base, the set
will automatically scan each channel for ground
stations in range of the aircraft and will select one in
the following order of preference.
1. Idle AGRAS stations.