[Elecraft] Pecker blanking, NB & NR

[VR2BrettGraham]

Breaking out what KA1J said in reply to ex-VR2BG/p in another thread:

> As to the OTHR, I can't say I have been aware of it at my QTH and
> that may be a result on none locally or maybe a lack of adequate
> antennae (all wire antennas hung in trees). But, my second radio was
> a Drake TR7 and the Russian "Woodpecker" was horrible back then and
> Drake had a modification to their noise blanker that was predictive
> for that and it worked wonders!
>
> It may be asking too much to think that Elecraft will improve their
> noise blanking functions to meet this need. I'm not an engineer and
> don't understand the limitations between difficult and impossible in
> this regard. I do know power line noise from Amtrak's catenary
> overhead power lines is killing my reception and there is nothing I
> can do with NB & NR settings in the K3 to mitigate it. Something more
> repetitive as OTHR might have better success at resolution. Still, if
> there were a better way to reduce the effects of power line noise or
> digital RF producing devices, that would certainly be of benefit to
> almost all of us.

I've heard OTHR from W1/W2/W4 on remote receivers at what I would 
consider lesser stations than yours, Gary.  If you were chasing XR0YG or 
T2YY on 17m around 14-15 GMT 2013-03-14 you might have been able to hear 
one.  Have a look at what was spotted - several EUs saying it was ZC4 
yet again & a W4 not sure if it was radar.

It's out there, you'll hear it if you're in the right place, at the 
right time, should one be QRV, the band is open & you know what it is.  
Take one of those away & it might as well not exist.  As far as that one 
observer is concerned.  Oh, if we all were so lucky to be blissfully 
oblivious to what's actually going on on the bands... ;^)

The mod you mention for the TR7 were component changes that changed time 
constants of the rig's REACTIVE blanker to better respond to what the 
original U-land woodpecker's pulses were like.

The only PREDICTIVE blanker I'm aware of was the one we did at AEA.  A 
pulse generator that the operator could sync with the OTHR (and vary 
blanking width) would chop off the antenna using a DBM for a gate (the 
blanker was external, sat in front of radio in line with the feeder).

The K3 already has the gate, figuring out when to wiggle something isn't 
a major task - it's more a matter of whether there's a way to bring the 
wiggle to the gate & the user interface for controlling the wiggles.  
Nearly daily OTHR on 40 & 80m from my country that can be heard in W6/W7 
has been around longer than the K3, so it might have crossed somebody's 
mind - or maybe not.

The problem with noise like you're suffering is if it isn't something 
that a reactive blanker is meant to react to, it won't help as you've 
found.  Likewise if the noise - or the crud you also mention - isn't 
like something the NR is meant to chew on, that won't help either.  To 
be honest, NR isn't something that will ever touch the crud - so yes, 
you're probably asking too much with that one.

There are more effective ways to deal with both (starting with fixing 
the sources), though I believe I have seen chatter here suggesting that 
some rigs have better blankers or NR than Brand-K's.  So let me suggest 
asking some mates with other rigs to come around & see what they're 
like.  If there is one that does better, then that suggests there's 
probably room for improvement of the K3.  Report back here, don't get 
discouraged by the user community's usual reaction to anything said to 
be anything other than perfection & perhaps it'll kick something off & 
in the end everybody ends up with something that works better.

73, ex-VR2BG/p.