Re: Nokia pa on 13cms? - Doherty


Neil Smith G4DBN
 

Any indication of two-tone IMD performance vs power, Robin? I have a few of those PAs to convert.  I was expecting to have to de-rate them significantly for SSB, although my main use would be for CW and digimodes.

Neil G4DBN

... I am seeing a nice solid 15A total now, about 11A on the carrier side, 4A on the peaking side, I think this is about flat out for this amp. ...  I found a resistor fault on the biasing of the drive amp and corrected that, it is now stable where as it was all over the place before. 

The SMA lead connecting the amp to the dummy load (a 250W slab load out of an old band IV transmitter) gets quite warm after 30 seconds of carrier so something is coming out :) 

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