[Elecraft] Help-damaged front end?

[Joe Wilkowski]

For What it is worth, during the course of construction on my K2 I 
inadvertently scrambled the K2's eprom storage with ESD.  (Electrostatic 
Discharge)  In one instance I had to do a complete reset of the MPU and 
memory back to the factory defaults. Only at that time did the receiver come 
back to life again.  In my opinion, the little K2 is very susceptible to ESD 
( I was wearing a wrist strap) and the thunderstorms you speak of could have 
definitely jumbled the K2's data storage.

/joe
----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at earthlink.net>
To: "john" <johnmb at nc.rr.com>; <elecraft at mailman.qth.net>
Sent: Saturday, December 16, 2006 7:30 AM
Subject: RE: [Elecraft] Help-damaged front end?


> 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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