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HPA Section of ANDREWS ex- UMTS PCB

In this section I describe the modification of the HPA, High Power Section of an ANDREWS UMTS unit to be used for 2320Mhz.

 

 

This section 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

MRF 21125 (2x par) 28Vdc +5Vdc 13dB 125Watt (2x)
 

Using the multipole 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) 

Ir= 500mA  ( MRF21045 )

Ir= 500mA  ( MRF21125 )

 

I first modified the input section: U17-FLL57 and got 1.5Watt out with 7mWatt drive.

After this I used the entire set-up and applied 24Vdc on the MRF's

The final modifications are shown in below picture. Note: I consider to further optimize the final stage as not much was done on this.

Currently 28Vdc applied with the over on: >150watt out.

 

The final HPA with covered PCB: Good for 150Watt RF output

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