[Elecraft] K2 - Resonate noise on audio

[Don Wilhelm]

John,

Those "resonances" appear to be similar to what I observe when the 
soundcard input is overdriven.
See what happens if you reduce the audio into the soundcard.

Did you replace the crystals on the RF board as well?  If so, I hope you 
re-used the insulators under the crystals.  They were needed in the 
Field Test boards (serial numbers 100 and below) - boards used after the 
Field Test had more complete solder masking and were no longer necessary.

73,
Don W3FPR
On 3/19/2014 1:01 PM, Jason V wrote:
> Attached a dummy load
> and tuned to the 7Mhz birdie.  When ever the birdie was within the filter
> the resonance would be present, outside it goes away.
> Links to screen shots.
> No birdie on cw filter. http://goo.gl/qvMGOq
> birdie @ ~633 Hz. http://goo.gl/irDakg
> birdie @ ~721 Hz. http://goo.gl/lBEacm
>
> So I brought the Radio to work and put it on the IFR 1900 and it Tx's and
> Rx's just fine.   Probed each of the new crystals and they all appeared fine
> as well, steep skirts, consistent width, and no spurs.  I have screen shots
> of the IFR if needed.
>
>