Re: QCX-20 ... low output power (~1.5 W) #qcx #20m


Mike Easterbrook
 

Hi Rob
This sounds very similar to my experience. Using a straight key l get 4W most times but occasionally >1W - in this condition total current if I dare keep key down long enough is 900mA versus 450mA for "normal" i.e. 4W output.  All these at 13.8 v at input connector. Compressing turns or adding one turn to L3 or reducing supply volts to 12 eliminates problem. If I change to paddle & key a series of dits I can can see about 1in20 dits on the power meter (analogue) where the output drops. This avoids trying to troubleshoot key-down with rapidly frying finals!

What total current are you drawing when output is low or high?

My best guess is that something in the PA or shaping is on the edge of self-oscillation.

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