Re: U3S fault - non sinusoidal output after filtering


Alan G4ZFQ
 

I didn't take any 'before' photos as there was nothing wrong then.
With my lack of good scope experience I'm always wary of what I see under fault conditions, that's when I wish for a "before".

The basic U3S PA is so simple that given a good input waveform there seems little to go wrong. All it needs is a steady supply voltage and good joints.

The photos are there now, I hope someone has the answer.

73 Alan

The
output voltage before was around +/- 8V peak to peak sinewave for most of the lower bands. Now it is lower and distorted.
Sometimes I have had a non-50 Ohm load on the U3S output and maybe the high VSWR did some damage but the output power has always been under half a Watt.

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