[Elecraft] CAL FIL question on K2 #4565

[BobConvers at aol.com]

I completed assembly of #4565 and all seemed well.   I used Spectrogram to 
perform CAL FIL using the N0SS article as a guide, but chose 650Hz as my 
sidetone freq since I thought I preferred a slightly higher tone, and selected 100Hz 
as FIL4 bandwidth.   I completed the CAL FIL process, with all values of the 
BFO parameter and BFO freq consistent with (not quite identical to) the manual. 
  

After tuning around the bands for a while (and having a ball!), I decided 
that the sidetone freq was too high and 600 Hz was probably what I wanted, after 
all.   So I selected 600 as the sidetone and tried to re-do CAL FIL.   CW 
NORMAL went well, and I got slightly different values than for 650 Hz, as 
expected.   Most of CW REVERSE seemed OK also - except for FIL1 and FIL4.   For FIL1, 
the BFO parameter was EXACTLY the same as for CW NORMAL, and for FIL4 the BFO 
parameter was the same as the bandwidth center value.   Specifically, here is 
what I found:

Using band noise at 10.115 since it was quieter than other bands on a 
Saturday morning, I found the BFO parameter at center of bandwidth (lowest tone of 
background noise) to be about 151 (same as on the previous 650Hz run).   Here 
are the BFO parameters for the four filters on CW NORMAL and CW reverse:

CW NORMAL    -     FIL1: 122;   FIL2:114; FIL3: 112; FIL4: 110

CW REVERSE -     FIL1: 122;   FIL2: 155; FIL3: 153;   FIL4: 151

I understand that all BFO parameter values for CW REVERSE should be ABOVE 
bandwidth center (151). The only possible complicating factor I noted was that 
occasional signals could be heard (actually seen) on the band, manifesting 
themselves as spikes on the Spectrogram display. Actually, it was one of these that 
leads me to believe that I was properly getting a reverse display between CW 
NORMAL and REVERSE, since one spike appeared at the right edge of the 
Spectrogram display on NORMAL and at an equal distance from the left edge on REVERSE.

I would appreciate suggestions on what 's happening.

73,
Bob, WO3E