[Elecraft] KSB2 bandwidth - 1.9kHz - SOLVED !

[Baker]

It's nice when you find a solution, not so nice when the answer is 
obvious !

I posted a thread awhile ago about why, although everything seemed to 
be working OK on TX and RX , measurements I made showed my KSB2 filter 
response dropping off at about 1.9kHz instead of the 2.5kHz determined 
by the capacitor values I had selected. RF measurements confirmed that 
the filter B/W was indeed correct. So what was wrong ?

I spent quite a lot of time and received a number of mails offering 
guidance, however the 'problem' remained - until today.

I read  mail on another subject which mentioned that the K2 headphone 
socket has HF rolloff. Guess what, for convenience that's the one I 
have been using for audio out to my soundcard !

When I use the speaker socket 'problem' solved, a textbook filter 
response.

Just a minute, a van has driven up and men in white suits are coming 
to the door.....

73

Stewart G3RXQ