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HARRIS
888-9058-001
WARNING: Disconnect and lockout AC primary power prior to servicing
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INPUT/POWER DIVIDER PWA:
In Driver modules the pad is constructed using three resistors. The resistors are selected
using Table A-2, (817-2100-639) Input Attenuator/Driver.
8.5.2.3 ISO Volts Check
Adjust PA power to 250 Watts. For a high band driver use 150 Watts aural and for a low
band driver use 65 Watts.
If necessary, manually disable some of the other modules to bring the drive level up as
required.
Measure the voltage at P1-2 on any one of the four quarter modules. (They are wired in
parallel.)
Verify the value to be 0.3 Volts DC or less.
To test the fault threshold, remove the RF Drive.
Using an isolated DC supply (possibly a 9 Volt battery and a variable resistance), inject
voltage at P1-2 of any quarter module and slowly increase voltage until the module
faults.
The module should trip off between 1.7 and 2.1 Volts.
8.5.2.4 Overdrive Check
Perform this check only after verifying that the module gain adjustment is correct. See
paragraph on Gain Check located elsewhere in this section.
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There are two ways to set overdrive, the first one requires a bench RF amplifier and
power measurement equipment. The second field method simply sets the reference
input voltage at the comparator to about the same level.
BENCH CALIBRATION:
Pre-set the Overdrive Pot R101 fully clockwise
MODULE TYPE
DRIVE LEVEL
TRIP TOLERANCE
High Band PA
120 Watts CW
2 Watts
Low Band PA
35 Watts CW
1 Watt
Low Band Drivers
140 milliwatts CW
10 milliwatts
High Band Drivers
350 milliwatts CW
10 milliwatts
To set the trip point adjust R101 CCW until the module faults and gives a blink code 2 on
the Red LED.