User's Manual

351804-1 Rev. 100

COM5000-8 TECHNICAL MANUAL

5.4.1.3 PA Controller PCB Assembly Maintenance

To gain access to the PA Controller PCB, proceed as follows:

1. Loosen the two "captive" screws that secure the Filter assembly to the 1.25kW PA Module front

panel.

2. Carefully move the filter module up to past its vertical position and make sure that it "leans back"

onto its back stops.

3. For location of the PA Controller PCB see figure 5.4.1B.

Adjustments:

The following adjustments should only be performed when a PCB assembly has been repaired in the field.

All PCB's are factory aligned prior to shipment. Also, this adjustment should only be performed if the

Driver/Splitter, 350 W Amplifier and Harmonic Filter adjustments have been completed.

Adjustments to perform: U3, Vref voltage

VF, VFL and VR

Nominal Power output, 50 Ohm, 1000 W

2:1 VSWR Power output, 500 W

DRVR Q1FLT Window Comparator

Initial potentiometer setting:

Potentiometers may be preset by measuring resistance and adjusting as shown below:

Note: The purpose of presetting the potentiometers is to avoid drastic misalignments that

may damage the equipment when power is applied.

If the potentiometers listed below have not been replaced or adjusted, presetting

should not be performed.

Resistance measurements must be performed with the PA Controller completely

installed in the 1.25kW PA Module (all connections secured) but without 50V supply

voltage applied.

Note: Perform the following adjustments in the order listed below.

CAUTION: RF HAZARD

ALIGNMENT OF THE PA CONTROLLER CAUSES

EXPOSURE TO RF