[Elecraft] K3 Narrowing the filters on SSB

[Tony Fegan VE3QF]

Don,

    At present the filter centre frequency is unchanged as the filter 
Width is reduced. If the centre frequency on SSB could be reduced by 
half the change in bandwidth then the LO-Cut frequency would remain the 
same. This is the same as how the Hi-Cut works. If we now add another 
variable so that when the bandwidth goes below about 2.2KHz, we slightly 
reduce the reduction in centre frequency, then this could start to raise 
the Lo-Cut frequency up to about 500Hz by the time we reach a bandwidth 
of 1.0KHz.
    This would allow the Width control on SSB to be used just like on 
CW. Just one control right down to the narrowest bandwidth.
    I tried your suggestion of moving the VFO at the narrower bandwidths 
but did not find any improvement over raising the Lo-Cut frequency. I 
was careful to tune in to signals close to their correct frequency and 
not where they sounded best. I found that a signal in the clear could be 
copied down to very narrow bandwidths but with QRM it was easier to copy 
on a slightly wider bandwidth. Of course it all depends on which side 
the QRM is.
    Maybe this topic should be renamed to "Digging in the dirt". I like 
looking for those very weak signals. At least my ears work fairly well, 
even if the associated processor is a bit suspect.

73
    Tony Fegan VE3QF


Don Wilhelm wrote:
> Tony,
>
> If you loose substantial intelligibility when moving the Hi-cut to 
> narrow the SSB width, try moving the VFO just a bit.  With a properly 
> tuned SSB signal and Lo-Cut set to 0.25, I can dial Hi-cut down to 
> about 1.05 and still understand what is being said.  If the signal is 
> slightly mistuned, then intelligibility suffers when Hi-Cut is reduced 
> below 1.85.
>
> The problem with making a 'center tracking' SSB width control is that 
> it would do the same thing as Hi-Cut does now - I don't know how that 
> would solve anything.
>
> 73,
> Don W3FPR
>