[Elecraft] Help-damaged front end?

[Don Wilhelm]

John,

Yup, thunderstorms can put some big surges on unterminated hunks of coax.

If it receives any signals at all and you can tune the signals, then it is
unlikely that everything between the mixer and the audio output has been
damaged.  That leaves only the preamp for active stages - turn the preamp on
and off to see if it works, you should see about a 14 dB change (2+
S-units).

If the preamp check works out fine, that leaves only the bandpass filters,
lowpass filters and the T/R switch in the base K2 and the KPA100.  Since you
said it transmits fine, the filters are likely not the problem (a filter
problem would have more impact on transmit) -  the most likely thing is one
of the diodes in the T/R switch is damaged.

I would first do the DC voltage measurements on the T/R switch diodes in
both the base K2 and the KPA100.

73,
Don W3FPR


> -----Original Message-----
>
> I've got a K2 / 100 that has had a dramatic loss of sensitivity.  This
> occurred after a thunderstorm, when the antennas were
> disconnected outside
> the house, but there was still some residual coax feeds (unterminated)
> still connected to the K2.
>
> Where to start to look? Appears to have lost sensitivity on all
> bands, all
> modes. Transmit is still fine (at least CW) .
>
> Thanks
> John
>
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