Hello Elecrafters,
I recently finished construction of my first K2.
I was very careful about ESD precautions during construction. While performing
the transmitter alignment it was never in transmit for more than just a few
seconds. The PA transistors and heat sink were all properly installed. The
rig had correct output power on all bands. It was being operated from an
Astron 4 amp supply with about 13.5 volts output.The transmitter was
terminated into a known good commercial quality 50 ohm load. At no time did
the heat sink get more than slightly warm. In other words the PA transistors
were not abused in any way.
I have not yet even made the first QSO with this rig. This morning when I
turned it on to listen around the bands it came on for a few seconds and then
failed.
Some clever and careful trouble shooting revealed that Q7 PA transistor is
shorted.
I have some spare 2SC1969 transistors but they are from a different
manufacture. Should I use these or get new ones from Elecraft? According to
some previous posts there may be a problem with other transistor brands.
Is this type of K2 failure common or just a fluke? I have never had any kind
of PA failure in any other rig that I have owned over the years.
Thanks for any thoughts that you may want to pass along.
73, Bill - K6WLM
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