The PA uses an MRF 141G Mosfet device rated for 300
Watts out with 14dB gain. The circuit itself
is quite simple - see the data sheet for teh MRF141G - and would
have been finished a long time ago but for the output
transformer.
Andy
G4JNT
Andy.
I've used the transformers from the Granberg application note for the
MRF151G for comms relays on band 2. This transformer
arrangement appears very efficient and did not need the recommended ferrite
sections. I would suggest you try the 25 ohm coax line transformers but
make them just a little larger then Granberg suggests.
Another method is to use two sections of RG58 or its PTFE equivalent in
parallel to get the correct 25 Ohm impedance. These are not quite so efficient
as the semi rigid but are still OK.
I don't have a spare semi rigid transformer, but I'll bring one of the
commercial ones produced by Communications Concepts in the USA on Sunday. You
may be able to create an easy way to duplicate it.
Regards
David 'MRF
