[Elecraft] K3: Rob Sherwood's full text reply

[ab2tc]

I currently only have the 2.7kHz 5-pole filter installed and experience
absolutely *no* difference in sound switching between USB and LSB on noise.
My DSP filter setting is 300-2700 which is my default when QRM is light. I
also watch the signal with the spectrum analyzer program SR5 and see my
slight high cut from the equalizer, but otherwise no tilt. If there was a
tilt, it would reverse when switching between USB and LSB. Maybe I have been
lucky. I have the 1.8kHz filter on back order for use during contests or
other extreme QRM conditions. Only time will show if it was worth the money.
The brick wall feeling of the DSP filters is something else! There is simply
absolutely *no* sign of a beat note on the "wrong" side of zero beat
whatsoever. Never experienced that with a non-DSP receiver.

Knut - AB2TC

DOUGLAS ZWIEBEL wrote:
> 
> Okay...I sent out about a dozen private "forwards" around 0800z.  Just
> got back on line, and my in box double that again.
> 
> So shown below is a cut/paste of the full text NCØB reply.  Nothing
> earth-shattering.  I also received (from a separate source) a note
> indicating that the 250hz filter (which, as mentioned below, is "more
> like 375hz") came in at 98, which seems to fit with what Rob is saying
> (but Rob never told me 98).
> 
> ENJOY!
> 
> de Doug KR2Q
> 
> 
> from	Rob & Terri Sherwood <rob at sherweng.com>
> to	DOUGLAS ZWIEBEL <dougzzz at gmail.com>,
> date	Fri, Apr 18, 2008 at 10:27 PM
> subject	Re: K3 various roofing filters
> 	
> 	
> Hi,
> The results are on my web site now. http://www.sherweng.com/table.html
> 
> While I did not include the 250 Hz filter (which is more like 375 Hz),
> it fits between the 200 and 400 in dynamic range (DR3).
> They all work.  I doubt anyone could tell the difference on the air
> from a DR3 standpoint.
> One can certainly tell the difference from a bandwidth standpoint.
> Personally I would use the 500 and 200.  One could also choose the 400
> and the 200.
> On SSB I think I would add the 2.1.  One can always set the DSP to 1.8
> when needed.  If a contester only, maybe the 1.8 instead of the 2.1,
> but I would have to evaluate that over time, and I did not have the
> 2.1, and I did not listen to the K3 in an SSB contest.
> 
> The 2.7 in my borrowed K3 had some passband tilt or ripple, and I
> could never get LSB and USB to sound the same on noise.
> Feel free to post any of this on the reflector.
> 73, Rob Sherwood, NC0B
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