Previous accidental post before reply was finished...
It can be anything that disrupts the signal path, directly or indirectly,
including a complex diode switch network that is the literal switching
device and runs all the state changes in the unit.
Possibilities include a messed up configuration. This could be in memory
only, but you seem to have checked that out.
Possibilities include the literal pins of the filters becoming oxidized.
This seems less likely due to two of them going down at the same time. Try
removing the two filters that cut out from the filter configuration. Do it
one at a time and then both. See what happens. Does the K3 work if the SSB
filter is used as the roofer for the CW bandwidths? If so, open up the case
to get access to the filters. Use a tiny, tiny (really tiny) bit of oxide
remover like Deoxit on each pin tip and do some repeated insertion and
removal. This could restore it, if oxidation on pins actually was the
problem.
Possibilities include one of the switching diodes having a poorly wetted
solder connection to the PCB land (I had two of those intermittent in my K3
many years ago, that would change, make contact, break contact with
temperature change. Took a little doing to run it down. Having two on their
own intermittent schedule was an enormous confusion factor. Or one of these
could have shorted, which could affect more than one circuit at a time. But
that was a board fabrication issue which they took care of years before
yours was made.
These paths can be traced if you can read the schematic, use a voltmeter,
take the unit apart, etc. I did it successfully and I don't work for
Elecraft. But if you're not into that level of electronic snooping you
probably need to get it to someone who is. Nobody qualified in DL land that
works on K3's? That would be hard to believe.
73 and Good Luck,
Guy K2AV
>
> On Tuesday, June 23, 2015, wrote:
>
>> Hi folks,
>>
>> after three weeks not using my K3 (Antenna disconnected, power off) I
>> observed a very strange thing:
>>
>> When turning the bandwith down to 500Hz, the loudspeaker goes deaf
>> despite separate 250Hz and 500Hz filters installed!
>> This happens only to the main receiver, the sub receiver performs as
>> wanted.
>> When selecting a bandwith above 500Hz the K3 works as normal! It seems as
>> the K3 is not selecting the smaller filters in the RX path.
>>
>> Did update firmware, resets, restored old configurations...last but not
>> least the Elecraft hotiline could not help further.
>> The only solution is sending it back.
>>
>> Did anybody observe a similar thing?
>>
>> S-Nr. Is 7629.. 2,8kHz; 2,1kHz; 1,8kHz and 500Hz/250Hz filters installed
>> Apart from the 2m module fully equipped!
>>
>> Quite lost at the moment.
>>
>> 73s
>> Bernie
>> DL5RDP
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>
>
> --
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>
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