[Elecraft] K3 NB problem

[Wes (N7WS)]

I experienced the same phenomenon as did Larry.  Some of this was the "fault" 
(i.e. normal operation) of the noise blanker; some of it was due to the 
absolutely abysmal quality of too many of the signals. Regrettably, there were 
probably some K3s contributing to the mess if some recent QSOs I've had with 
other owners are any indication.  Although I often get unsolicited kudos for my 
audio, I recently had a 17-meter ragchew with a W6 transplant in GA whose K3 
sounded simply awful and looked it on the spectrum scope.

Regarding the K3 NB, frankly, I wonder why, with a radio with so many "smarts" 
built in, we have to adjust I-F NB parameters at all.  Setting the threshold 
automatically, under most conditions, should be automatic and extending the 
blanking pulse width to match the noise impulse duration should be trivial.  
See: http://k6mhe.com/n7ws/Noise_Blanker.pdf  for some ancient work.

(I actually wrote this paper as a final exam for a technical writing course I 
took.  We were told to write something suitable for publication, including 
letters of submission and a release from the company I worked for.  I said to 
myself, "Self, you've done all of the work, why not just for the heck of it 
submit it to a ham radio publication?  Since the company only gave "published 
papers awards" for peer-reviewed publications, I figured I really didn't require 
their approval so I sent it to Ham Radio Magazine and they paid me instead.  A 
couple of years later a guy said to me, "I see your circuit was published in 
Bill Orr's Radio Handbook."  First I knew about it. One would think that a guy 
who stole your work would at least give you a free book; but no.)


  On 11/20/2015 8:00 PM, Eric Swartz - WA6HHQ, Elecraft wrote:
> Hi Larry,
>
> For the IF NB I usually use a level of 3, or 4 max, with a narrow typically 
> for the width. This generally works quite well for me with minimal intermod. 
> More aggressive thresholds and wider widths significantly increase the 
> likelihood of nearby strong signal intermod with IF based NBs.
>
> As another poster mentioned, the DSP NB can be cascaded after the IF NB, or 
> just on its own. So trying different combinations of these may also help in 
> your situation.
>
> Eric
> /elecraft.com/
>
> On 11/20/2015 3:00 PM, Larry - K1UO wrote:
>> I discovered the source of a “noise” I was complaining about on 80M cw this 
>> AM.  I finally noticed that it would always come on at exactly the time VK9WA 
>> said “UP”!!   and varied in intensity and duration until he answered 
>> someone..at which time the noise was gone and S meter returned to S1!! Seems 
>> like the NB  settings on the K3 are causing IMD and phase noise from the 
>> pileup up the Band a bit to sound like rain static and jump to a level of 
>> S5-6 on the K3 meter!  Never ran into that before with a K3...  Then again, 
>> except for this new electric fence pulse, I never needed to use the NB for 
>> anything at this previously dead quiet location.    Any ideas on what 
>> settings I should use or try for this electric fence noise? Possibly the 
>> settings that I am using are too aggressive and would cause this?
>> Regards
>> Larry  K1UO