Re: I tried Support without a word in return -- so I'll try this

Posted by Mike K8CN on Aug 04, 2011; 1:53am
URL: http://elecraft.85.s1.nabble.com/Re-I-tried-Support-without-a-word-in-return-so-I-ll-try-this-tp6650837p6651015.html

Rick,

Presuming that you've already taken Don's customary advice (check all solder joints and re-heat anything that looks suspicious) in the vicinity of the 1st crystal filter, I would verify that one of the other crystals (X1 through X4) hasn't been inadvertently placed into one of the slots for X7 through X11 (the 1st variable bandwidth filter) or X5/X6 (the post-IF amp filter), and I would carefully check the varactors D29 through D34 to be sure they're the correct diodes.  

If these checks don't reveal anything amiss, I would repeat the BFO Test and BFO Alignment (more often referred to as CAL FIL) from the Part II Alignment and Test procedures to be sure that your BFO tuning range and BFO frequency settings for the various filters FL1 through FL4 haven't effectively put the down-converted RF signal on the skirts of the 1st crystal filter's passband.  Since you have an external RF signal source, you could use Spectrogram to check the position of a known input frequency at the antenna when it's mixed down to the audio range -- if you don't see the spike in the audio spectrum inside the filter's response passband, that's a good indication of the BFO frequency being incorrectly set. All of this presumes that you have an independent means (i.e., good external counter) to check the frequency of the RF input signal and that you observe a peak in the audio response when the K2 frequency display matches the RF input frequency (CW mode, not USB or LSB).

Don may have other suggestions based on his extensive knowledge of common K2 maladies.

73,
Mike, K8CN