CW filter weirdness

[Chris Iwata]

Not all Heathkit CW filters are interchangeable:  Eg, the CW filter  for the 
SB104 can't be used on
most other SBs or HWs though it physically looks the same.  Its center  
frequency and impedance is different.
 
Either the center frequency of your filter is incorrect, or the BFO crystal  
for CW is off frequency.  The center freq is usually stamped on the  filter.  
Check your manual to see what the BFO freq should be.
 
Chris, KL7DM
 
In a message dated 2/12/08 11:46:52 A.M. Pacific Standard Time,  
wd4scz at AOL.COM writes:

OK, I am  in need of some erudite advice on a crystal filter anomoly in an 
SB-101.   I used to look at crystal filters as pretty much a "box of rocks" put 
them in  like they are marked and they work.

Here is what happens, when in CW or  USB with the filter selector in the SSB 
position when you tune to zero beat  the carrier as you increase the frequency 
you get the high pitch dropping to  zero and an abrupt cutoff past. That is 
the high side is greatly suppressed,  as you would expect.

Switching the CW filter in, the background noise  diminishes, but now tuning 
to zero beat, there is no abrupt cutoff nor is  there the narrow notch on 
would expect. For those familiar with Direct  Conversion receivers the blasted 
thing is just about like tuning an  HW-7.  







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