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Driver Section of ANDREWS ex-UMTS PCB

In this section I will describe the modification of the driver section of an ANDREWS UMTS unit to be used for 2320Mhz.

 

 

 

The smaller PCB contains following components:

 

Component

Vds

Vgs

Gain

Pout

U17

15Vdc

-5Vdc

12.5dB

32dBm

FLL57

15Vdc

-5Vdc

11.5dB

36dBm

MRF 21045

28Vdc

+5Vdc

15dB

45Watt

 

Using the multippole connector the various connections can be found here: Connections

 

First test of this section of the board was on the DC levels and currents.

Following settings were found to be more or less optimum for the time being:

 

Ir = 400mA ( U17 & FLL57) ( this value is heavily influencing total gain!!)

Ir= 280mA ( MRF21045 )

 

After some modifications I have wind up with: 10mW input => more than 10Watts output  Gain: 30dB

Modification on the U17 -input & output section

 Modification on the MRF 21045 -output section

20 jan. 2012 Re-installed the aluminium cover to avoid oscillations and re-tested gain / power.

27 jan 2013 Removed the driver section from the original unit and installed on seperate ALU cooling block.

                 Be sure you copy all the holes in the new cooling block, otherwise you will be faced to various shorts on the underside of the PCB.

                 Re tested total driver section with supply voltage for MRF to 24volt.

Results: 13dBm input => 20Watt ( 2320MHz)

DC adjustment section on top of the cover

 Completed driver section installed on coolingblock

SSPA with cover installed

Backside with computer cooling fans

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