Hi All. I just did something real stupid by forgetting that my antenna was
grounded and transmit my Argo into a dead short. Now the power meter just
slightly wiggles at a power setting what once was 5W. I'll open it up and try
to trouble shoot the voltages up to the power amp and scope the driver input
and output to see if that is blown. The ALC LED does not light either on TX
with a CW key. Not sure of the criteria for that to light up. It is very
likely I toasted the 2SC3133 output transistors. I went to RFParts.com and
they call for a replacement of using a matched pair of 2SC1945. The price is a
little more than I was expecting. My question is do they really have to be
matched pairs? It seems just adjusting the bias voltage on each would be
sufficient. I'm not exactly sure where they should be biased besides have an
equal collector current at idle. I see some on ebay, but kind of leery of
those being gray market parts since they're
coming from Hong Kong.
Any thought/suggestions on repair and alignment?
Scott, KB0KFX
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