[Elecraft] K3 Passband/DSP Filter Display Question ?

[Don Wilhelm]

Phil,

Yes, "FC" means Frequency Center, which is where the passband is 
centered.  The "*" means it is the default (the same as your sidetone 
pitch setting for CW).
You did not ask about the Width display, but it is the width of the 
passband and extends half that vale on either side of FC.  Those numbers 
are much more accurate than the low resolution graphic on the display, 
but the display gives you an idea about which part of the ballpark you 
are in.

For SSB and other voice modes, the default FC is 1.5 kHz, but I would 
suggest you not worry about that, but use Hi-Cut and Lo-Cut instead of 
shift and width and directly define the low and high frequency edges of 
the passband.   You will not be able to cut much more than to 350 or 400 
Hz on the low end before loosing intelligibility, but you can cut the 
high end substantially and still maintain intelligibility although some 
of the voice characteristics become a bit more 'pinched'.

Attempting to use Width and Shift with voice modes will require you to 
reposition the Shift each time you change the Width.

73,
Don W3FPR



On 1/31/2014 1:48 PM, Phil Hystad wrote:
> I have had my K3 for four years but rarely make use of the passband tuning features.  Today though I was experimenting with APF and the passband controls and learned that I really do not know what I am doing.
>
> In particular, the VFO B display is a mystery to me during passband tuning and APF SHIFT tuning.  For example, in passband tuning (APF not enabled), the VFO B display says FC and then a number like 0.70 or whatever.  What does "FC" mean (I can guess, but that would not be useful) and what is this number.  I scanned all the documents I have and have not found descriptions of the content of the VFO B readout during passband tuning.  I know it has something to do with shifting the frequency of center (I think) so maybe FC means Frequency Center.  Also, there is an asterisk in the field, like:  FC  *0.68.  Maybe someone can interpret the meaning of that.
>
> If I knew the definition for passband tuning for the VFO B field content I could probably guess at the meaning of the APF enabled display which is similar such as:  APF  *0.68.
>
> I have found lots of description of passband tuning and that part of the display showing the passband width and position but nothing describing the VFO B contents (not covered in documentation on alternate VFO B displays either).
>
>