14: Maintenance
14-22
PRC1099A-MS
3. Key the radio without modulation.
4. Increase the output level until the power output is 20W.
The drive level should be approxi3 dBm.
Antenna Tuner
Board
To verify the Antenna Tuner board is operating correctly:
1. Connect an AT271/U (10 ft. whip with base) into the front panel whip
antenna base connector.
2. Press the front panel
Whip Tune
button. The tuner should go through
the tune cycle.
3. If the pulse tune tone indicates that the tuner did not achieve a correct
match, check the antenna connections and try retuning on a different
frequency.
4. If the tune cycle does not initiate, make sure the antenna mount or
long-wire adapter is opening the switch at the base of the antenna post.
Note:
The Antenna Tuner board circuitry is controlled by the
processor. A fault in the Processor board usually causes other
transceiver control malfunctions.
Processor Board
Many of the data and control functions on the Synthesizer, Display, Antenna
Tuner boards are under direct control of the processor. A fault in the Processor
board normally causes multiple malfunctions in the transceiver. Check the
Processor board by direct board replacement.
The lithium-ion battery for memory backup is located on this board. Replace
this battery if the radio does not retain channel memory when the radio is
turned off.
Display Board
The Display board should only be replaced if all other radio functions are
normal. Check the Display board by direct board replacement.