TM 1-1510-218-10
3C-11
NOTE
When storing a frequency, the second
actuation of the STO button must be done
within 5 seconds after selecting the
channel number or the first actuation of the
STO button. If more than 5 seconds
elapse, the control will revert to the normal
modes of operation and the se cond store
command will be interpreted as the first
store command.
After a frequency has been stored in memory, it
will remain there until changed by using the STO
button. Memory is retained even when the unit is
turned off for an extended period of time.
(5) Stuck Microphone Switch. Each time the
push-to-talk switch is pressed, the microprocessor in
the transceiver starts a 2-minute timer. The TX
annunciator on the transceiver control unit will be
illuminated whenever the transmitter is transmitting. If
the transmitter is still transmitting at the end of
2 minutes, the microprocessor turns it off. Most
intentional transmissions last much less than 1 minute;
a 2-minute transmission is most likely the result of a
stuck microphone switch. This timing feature protects
the ATC channel from long-term interference.
When
it
turns
off
the
transmitter,
the
microprocessor switches the transceiver to receive
operation. A stuck microphone switch will prevent you
from hearing received signals, or the two warning
beeps. The microprocessor then waits until the push-
to-talk switch opens to sound the two beeps.
To transmit for more than 2 minutes, release the
microphone switch briefly and then press it again. The
2-minute timer resets and starts a new count each
time the microphone switch is pressed.
(6) Overtemperature
Protection.
The
microprocessor regularly monitors the temperature of
the transmitter. If the transmitter gets too hot during a
transmission,
the
microprocessor
will
stop
the
transmission, and the sidetone will cease. When the
microphone switch is released, you will hear two
beeps. Press the TEST switch on the transceiver
control unit to observe the fault code. As long as the
temperature remains above the limit, the micro-
processor will not respond to a normal push of the
microphone switch. If you must transmit, however,
you can override the protection by rapidly keying the
microphone switch twice, holding it on the second
push. The shutdown temperature is 160 °C (320 °F).
(7) Self-test.
An
extensive
self-test
diagnostic routine can be initiated in the transceiver by
pushing the TEST button on the transceiver control
unit. The control unit will modulate the active and
preset display intensity from minimum to maximum to
annunciate that self-test is in progress. Several audio
tones will be heard from the audio system while the
self-test routine is being executed. At the completion
of the self-test program, the transceiver control unit will
usually display dashes in the active display, and 00 in
the preset display. This indicates normal operation. If
any out-of-limit condition is found, transceiver control
unit will display DIAG (diagnostic) in the active display
and a 2-digit fault code in the preset display. Record
any fault codes displayed to help the service
technician locate the problem. Refer to Table 3C-3 for
a description of the self-test fault codes that can be
displayed on the transceiver control unit. The TEST
button must be pushed before any fault code can be
displayed.
Table 3C-3. Self-test Codes
FAULT/CODE DESCRIPTION
00
No fault found
15
Frequency out of range
01
5 Vdc below limit
16
Forward power below limit
02
5 Vdc above limit
17
Transmitter temperature excessive
03
12 Vdc below limit
21
Tuning voltage out of limit at highest receive frequency
04
12 Vdc above limit
22
Tuning voltage out of limit at 118 MHz
05
Synthesizer not locked
23
Local oscillator output below limit
07
Noise squelch open without signal
24
No-signal AGC voltage too high
08
Noise squelch open without signal
25
Inadequate AGC voltage increase with rf signal
12
BCD frequency code invalid
26
Reflected rf power above limit
13
2/5 frequency code invalid
27
Transmitter timed out
14
Serial message invalid
