[Elecraft] Question about KNB2 Noise Blanker

[W3FPR - Don Wilhelm]

See comments below:
----- Original Message ----- 
From: "VR2BrettGraham" <vr2bg at harts.org.hk>
To: <elecraft at mailman.qth.net>
Sent: Saturday, January 01, 2005 9:37 AM
Subject: Re: [Elecraft] Question about KNB2 Noise Blanker 
(GainreductioninNB2 posit...


> W3FPR replied to KH6AT that gated noise blankers cannot be expected
> to work when the noise pulse is insufficient to reach the gating threshold
> & that more signal might improve performance when blanking weak
> noise.  Sounds reasonable, but...
>
> I believe my other radios have gated noise blankers.  They behave far
> better than the KNB2 in my K2 - even on noise that presumably is what
> the KNB2 was designed for (chain saws, dirt bikes & similar stuff that
> might be encountered by backpackers) - regardless of strength.
>
> Outside of the type of noise the blanker is tailored for, why would it
> be that a number of folks using one particular radio with a gated noise
> blanker (K2 with KNB2) find the performance to be lacking compared to
> other radios also with gated noise blankers?
>
OTOH, many have reported that the K2 blanker is better.  I don't know the 
real answer, but I can guess that the gain of a particular receiver ahead of 
the noise blanker would make a big difference.  Multi-conversion receiver 
designers have a lot more places to put the noise blanker (and more control 
over the gain at that point) than is possible in a single conversion 
receiver like the K2.  Try the K2 NB with the preamp set on to see if that 
makes any difference, you may be surprised.

73,
Don W3FPR