[Elecraft] Noise Blanker

[Vic K2VCO]

VR2BrettGraham wrote:

> Strange, I also find other radios' NBs to work fine
> on a wide range of noises & will do so without
> adding much of anything untoward.  

All noise blankers that I've used cause some degradation of the 
receiver's dynamic range performance.  This means that in a strong 
signal environment (like in a contest) you will hear spurious responses 
when it is on. This is of course a matter of degree, and I know there 
are sophisticated circuits that are much better than others in this respect.

> They can take a bite out of some atmospherics 

I have *never* used or even heard of a noise blanker that reduces 
atmospheric noise (by which I mean that generated by thunderstorms)! 
Yes, an antenna noise canceller can do this, but we're talking about 
noise blankers.

> The efforts to explain it away will not change the fact
> that the K2's NB is the worst performing NB of any
> radio I have ever used.

Then you must not have used the unmodified TS850s noise blanker!

> That the subject keeps coming up here does suggest
> there might be room for improvement, but again this
> is based on the invalid comparison with other radios,
> so we had best shut up, mate.

I don't disagree that the K2 noise blanker could be much, much better. 
But an improved one would be much more complicated. It would probably 
need to me built with SMT components to fit in the available space.

I think -- given the noisy environments that most of us live in, and the 
fact that this will only get worse -- that noise reduction should be one 
of the primary receiver design considerations.  Because of the 
difficulty involved in doing it without compromising dynamic range too 
much, the noise blanker should be designed as part of the basic 
receiver, from the start, and not as an add-on (although the module 
itself could be optional).

My dream receiver would have an adaptive, computer-assisted noise 
reduction system that would combine early noise blanking with DSP and 
possibly other techniques.  BPL is just one of many of the new kinds of 
noise we are facing.
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco