When S2 is in the OFF position, the AUTO DRIVER D7 is
disabled. This position is used only during factory test of the
transmitter.
With J5 in the “TEST” position, operation is the same as
described above except that drive “ON” signals can be applied
to all DriverModules except the “AUTO”driver without turning
the transmitter ON. This feature is provided as an aid to trou-
bleshooting.
S.2.2 Temperature Sensor/Power Foldback
Refer to Figure S-2 for the following discussion.
The PA RF amplifier temperature is monitored by two precision
temperature sensors mounted on the heat sinks of PA Modules
RF33 and RF34 (steps 1 and 2). The voltages from the sensors
are calibrated by AMB1 potentiometer R50 and AMB2 poten-
tiometer R51, buffered by operational amplifier U9, and ampli-
LOCATION COMPONENT FUNCTION/DESCRIPTION
D5 DS1 DRVR, illuminates when D7 is turned on
D6 DS2 OVER TEMP, illuminates when power reduction signal is high
D5 DS3 TEMP CAUTION illuminates when U3 comparators activate
E5 J5 Jumper plug to set Control Functions to Auto or ON
B2 R17 Adjusts the OFF threshold for D7
B2 R19 Adjusts the ON threshold for D7
A2 R49 Adjusts reference voltage output of U9-C, “CAL”
B2 R50 Adjusts calibration of sensor AMP 2
A2 R51 Adjusts calibration of sensor AMP 1
A5 R60 Adjusts TEMP LOWER threshold for U11
D4 S1 Selects D6 control function
E4 S2 Selects D7 control function
Table S-2. Adjustments and Indicators
(See Figure S-4)
Figure S-2. Driver Encoder Block Diagram
Temperature Sensor/Power Foldback Function
Section S - Driver Encoder/Temp Sense (A19)
888-2297-002 S-3
WARNING: Disconnect primary power prior to servicing.
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