[Elecraft] K2 Noise blanker- is it working?

[Don Wilhelm]

Stephen,

Turn the preamp on and scratch/tap the Q21 case with a metallic object 
(screwdriver) while turning the NB on and off.  If the NB is working, 
you will hear the sharp impulse clicks substantially reduced.

Many types of power line noise are not handled by the KNB2, it is great 
on impulse noise, such as that from an automobile engine (not diesel).  
The KDSP2 does a good job on many other types of noise.

73,
Don W3FPR

Stephen Prior wrote:
> I built the noise blanker kit for my K2 s/no. 4905 (I think) a few weeks
> back, and I am beginning to wonder if it is working.  I can not tell any
> difference between NB1, NB2, whether hi or lo threshold.
>
> It is said that it works against the sort of pulse noise I get here from
> power lines occasionally, yet it makes no difference.  Since all the cars in
> the family are diesel powered and I am some distance from a quiet country
> road, I have not had the opportunity to see whether it works on petrol
> engined ignition noise.  My experience with noise blankers in other radios
> is that you can usually hear some change when it is switched in, but I
> don't.
>
> Am I expecting too much?  Or could there possibly be a fault which would
> still pass the rx signal through the noise blanker board and yet stop the
> noise blanker working?  Had I not read how good it is supposed to be, and
> had I not made it myself, I probably would not be asking the question!
>
>