[Elecraft] Filter Challenged...I'm so confused

[Ron D'Eau Claire]

Good question. 

The K2 stores BOTH the filter and the BFO frequencies associated with
each filter "position". It uses both the filter selection and BFO
frequencies for FL1 in transmit, so unless you play with the "main
tuning" having different settings for the BFO in FL2, 3 and 4 will not
affect the transmitted signal at all.  

The effect of changing the BFO frequency is to simply move the position
of the filter "passband" in relation to the "carrier" frequency. If the
other station is using a very wide SSB filter (say 100 Hz to 3000 Hz) by
changing the BFO frequency you can move the 2 KHz passband of the K2 SSB
filter to whatever part of that sideband you want - emphasizing the
higher or lower parts of the sideband and cutting off the rest. For SSB
signals using 2.4 kHz bandwidth filters, adjusting the BFO can better
"match" the K2's filter to the sideband being received, or it can be
used to cut off the lows or highs to help remove interference. That's
the basic purpose of "passband tuning" of course. 

Ron AC7AC
K2 # 1289

-----Original Message-----
--
> From: Ron D'Eau Claire [mailto:rondec@easystreet.com]
> 
> One reason for using the OPT1 filter in SSB for FL2 or 3 or 4 is to 
> produce the equivalent of "passband tuning". You can define different 
> BFO frequencies in FL2 or 3 or 4 that will "shift" the passband of the

> filter to higher or lower frequencies.

But if you do this, will you be transmitting on the correct 
frequency with FL2-4 shifted as you describe? Or will the received
signal (using FL2-4) BFO shift -- to do "passband tuning" in 
effect -- cause you to tune in the received station at a 
frequency different from where your K2 will transmit, using FL1 
in the transmit path?

I hope you understand what I'm asking. I don't have a KSB2 (yet) so I
can't experiment. 

Andy