[Elecraft] Running stations with k3

[Jim Brown]

On Wed,9/21/2016 3:59 AM, Bill W4ZV wrote:
> This is nothing new.  K3ZO has been doing this for about 30 years (at least)
> using wide filters and his ears as DSP.  I did this long ago with a TS-930S
> using SSB filters with CW VBT fully engaged which shifts two IF filters in
> opposite directions giving a broad overall response but peaked in the
> center.  See K3ZO's comments here:

Now we're getting to the good part of this thread, which I've found 
quite illuminating, because it explains user preferences for one radio 
over another that aren't obvious. Thanks to Will, Guy, and Bill for 
their very useful contributions to the discussion.

There's another VERY important factor related to bandwidth -- when we 
narrow the bandwidth to copy a very weak signal buried in noise (as 
opposed to QRM), the filter tends to ring at its skirts, making it more 
difficult to copy rather than easier. I find this to be true independent 
of which filter alignment I've chosen, and it's predicted entirely by 
classic filter theory. The K2, which sounds great when listening through 
its TX filter, has a multi-element crystal filter that it realigns to 
vary the bandwidth, sounds just awful when set for narrow SSB 
bandwidths. It's all due to the extreme phase shift in those filters.

As another example from my work in pro audio, I was hired to try to 
clean some really nasty buzz out of a "jailhouse" recording. This was in 
the late '70s, and DSP didn't exist. My tool was a very high quality, 
very narrow tunable notch filter with high and low pass filters, and I 
passed the recording though it a half dozen times to attack the 
harmonics of the buzz. With each pass, I reduced the buzz, but I also 
introduced more phase shift. So as the signal to noise improved, the 
intelligibility degraded.

73, Jim K9YC