[Elecraft] K2 BFO Frequencies

[K4IA@aol.com]

Tom

Nothing brings out the gremlins, real or imagined, quite like alignment.  It 
is sometimes hard to decide what sounds "right."  When I tried aligning 
following the guidelines in the Calibrate Filter section, I was way off and 
the sound was pinched badly.  Thank you so much for your work with 
Spectrogram because that got it to sound much better.  I think I am OK now 
although I have an issue because my tone changes upwards when going from 
F1/F2 to F3/F4.  That I know isn't right but I am not quite sure what to do 
with it.  

I suppose if the BFO frequencies were way off, you could be at a point where 
you are on the edge of the filter's ability and therefore performance would 
be degraded even though you the audio appeared centered in Spectrogram (?).  
When the book gives a certain spec and you are outside that spec, you have to 
wonder if you are getting all you can out of the rig.

In my case the low BFO was 160 cycles above where it is supposed to be when I 
run the BFO test in Part II.  Today it is 100 cycles high.  That is a lot if 
you are dealing with a filter that is only 400 or 100 cycles wide.  The tone 
change upwards sounds (to my tin ear) about like 100 - 160 cycles when I go 
to filters 3 or 4.  That coincidence makes me wonder.

So I have introduced 2 questions:

1.  What is happening to make the tone change when going to the narrower 
filters?

2.  Is the fact my "BFO low" is 100-160 cycles too high a significant enough 
deviation to warrant adding capacitance to C174 as suggested in the BFO Test 
section of Part II?

Thanks to you and all on the list for the help.

Radio K4IA
Craig Buck
Fredericksburg, Virginia USA
QRP ARCI #2550  FISTS #6702 CC 788 Diamond #64
K1 #470 K2 #2460
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