[Elecraft] K3/K3S noise blanker performance greatly enhanced (at my QTH) -- need testers

[Bob McGraw K4TAX]

I've found quite a number of articles discussing noise blankers and the 
implementation of such.   From my experience with radios on the desk, 
past and present, the hardware noise blanker works quite well.  On the 
other hand, DSP/software noise blankers have always been found to be 
marginal.

It seems we are insisting on tighter and tighter bandwidths {filters} to 
fight QRM.  While at the same time, the use of a tighter the filter has 
the adverse effect that causes the noise pulse to be fattened.    This 
is what Wayne was discussing in his recent post.  In another approach, 
use a wide filter ahead of the NB thus it can become more effective on 
blanking.  Wide pulses when blanked will punch holes in the audio.

There's a lot of history with Collins Radio and the implementation of 
noise blanking methods.  None of these use DSP schemes and in one 
system, a separate antenna was used to feed noise pulses to the blanker 
circuit.   I suggest one research the topic in this vein. One of my 
current radios on the desk uses a hardware noise blanker while the other 
one uses a DSP/software blanking system.  Both radios are from the same 
company.  It is amazing how much better the hardware noise blanker 
performs over the two radios which use DSP or software noise blankers.

73
Bob, K4TAX
K3S, s/n 10163



On 2/4/2016 8:45 AM, Wes (N7WS) wrote:
> Maybe this is an opportunity to rant about the K3/K3S noise blanker.
>
> Back on 12/8/15 K2AV wrote: "To those trying to get rid of a certain 
> noise, remember that there are 21+21+(21x21) combinations of IF and 
> DSP blanking. That's 483 combinations, not counting variations with 
> preamp/normal/atten settings."
>
> Now we're adding more?
>
> At the time, I composed a message that I failed to send.  It follows:
>
> "Personally, I don't want to "tinker" with 483 possible adjustments.  
> As I've said before,with a radio with this much computing horsepower 
> and the design talent at Elecraft I fail to understand why blanking 
> thresholds and duration aren't nearly automatic.
>
> I would also like to see a technical description beyond the 
> hand-waving in the manual of how noise blanking is performed.  For 
> example, I fail to see any dedicated delay in the signal path to 
> create timing coincidence between the noise pulse and the blanking 
> gate.  Perhaps it's inherent in the design, but I would like to see 
> some words that say so.
>
> If it's going to be necessary for me to set a blanking threshold 
> (something I think could be automatic) then why can't the radio 
> generate a blanking pulse that persists as long as that threshold is 
> exceeded.  Why do I also have to adjust that?  If the pulse is so long 
> that intelligibility suffers then that noise isn't amenable to being 
> blanked and blanking needs to be disabled.
>
> The K3 blanker is okay.  Although I no longer have it around to 
> compare to, I designed a pretty effective one in 1977.  Perhaps the 
> best blanker I've run across was in a lowly Yaesu FT221R 2-meter 
> multimode.  The worst was in my TS870SAT that otherwise was a good 
> performer and had great ergonomics.  I've said more than once that 
> Kenwood wasted panel space putting in a control for the noise blanker."
>
> End of rant.  Eric can close the thread now:-)
>