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:
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