Ericsson LBI-39175A manual Transmitter Alignment, PA Transistor Replacement

LBI-39175A

TRANSMITTER ALIGNMENT

The Transmitter consists of synthesizer, exciter, and power amplifier. These have been calibrated at the factory so the radio computer automatically adjusts RF power and modulation deviation, based upon Tracking Data. The following adjustments can be made by EGE PC Programming Software:

1.Modulation Deviation -- Change Tracking Data using "MRKMAINT" maintenance software. Follow the procedure given in "TRACKING DATA" section. Be sure to record the new Tracking Data and modulation levels. DO NOT CHANGE TRACKING DATA UNLESS THE LOGIC OR SYNTHESIZER HAS BEEN REPLACED. DO NOT CHANGE TRACKING DATA FOR ANY FREQUENCY OTHER THAN THAT GIVEN IN TABLES 2 AND 3.

2.RF Power -- Set RF power for system (EDACS) or channel (CONVENTIONAL) in the radio personality, using "EDACS3" programming software. DO NOT CHANGE TRACKING DATA UNLESS THE PA MODULE OR LOGIC PWB HAS BEEN REPLACED. DO NOT CHANGE TRACKING DATA FOR ANY FREQUENCY OTHER THAN THAT GIVEN IN TABLES 2 AND 3.

There are no other adjustments to be made on the transmitter. However, there are components located on the synthesizer and power amplifier, which appear to be adjustable. These are summarized as follows:

Synthesizer:	CV240, CV280, RV201
Power Amp - 25 W:	RV1
Power Amp - 50 and 110 W:	RV2

These components have been set at the factory, and are NOT ADJUSTABLE. ANY RE-ADJUSTMENT OF

THESE COMPONENTS WILL VOID THE WARRANTY OF THIS PRODUCT.

NOTICE

The components listed above have been set at the factory

and are NOT adjustable.

ANY RE-ADJUSTMENT OF THESE COMPONENTS WILL

VOID THE WARRANTY OF THIS PRODUCT.

PA TRANSISTOR REPLACEMENT

WARNING

The RF Power Transistors used in the transmitter contain Beryllium Oxide, a TOXIC substance. If the ceramic or other encapsulation is opened, crushed, broken, or abraded, the dust may be hazardous if inhaled. Use care in replacing transistors of this type.

To Replace the PA RF Transistors

1.Unsolder one lead at a time with a 50-watt soldering iron. Use a scribe or X-acto®knife to hold the lead away from the printed circuit board until the solder cools. Remove the mounting screws.

2.Lift out the transistor. Remove any old solder from the printed circuit board with a vacuum de-soldering tool. Special care should be taken to prevent damage to the printed circuit board runs because part of the matching network is included in the base and collector runs.

3.Trim the new transistor leads (if required) to the lead length of the removed transistor.

4.Apply a coat of silicone grease to the transistor

mounting surface. Place the transistor in the mounting hole. Align the leads as shown on the

Outline Diagram. Then replace the transistor mounting screws using moderate torque (9.4 kg.cm).

5.Solder the leads to the printed circuit pattern. Start at the inner edge of the mounting hole and solder the remaining length of transistor lead to the board. Take care not to use excessive heat that causes the printed

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