[Elecraft] K3 Noise Reduction

[Bob Schwerdlin]

For me, the best noise blanker was on my old Drake R4C.  That thing 
worked GREAT!

Bob, WG9L


On 12/15/2021 1:14 PM, Fred Jensen wrote:
> I find both the NB and NR on my K3 to be moderately underwhelming, not 
> sure why.  Ignition noise used to predominate in urban and suburban 
> areas and blankers like the one in the 75A4 were very effective.  I 
> don't know what Detroit did, but I haven't heard ignition noise in 
> years.  A general rule of thumb has always been to use blanking in 
> wider bandwidths which sort of makes sense I guess ... the blanking 
> pulses consume a smaller fraction of the overall signal passband.  My 
> understanding of the K3 NR is that the DSP processor tries to build a 
> matched filter around the signal on the fly.  It may be a bit too much 
> for the algorithms, I've never had much success with it on broader 
> noise such as power mains hash.  Backing off the RF gain seems to be 
> more effective.
>
> The best noise reduction I've ever encountered was on the receivers in 
> the transportable AN/TRC-96 2.5 KW HF ISB system back in the 60's.  3 
> voice channels and 16 TTY channels on the 4th. Don't remember the mfr 
> and don't know how they did it but you could literally make noise 
> disappear with minimal effects on the signals.
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> Jim Brown wrote on 12/15/2021 10:16 AM:
>> Lots of good advice here. A major problem with the K3 NB is the way 
>> it is described on screen and in the manual. There are two blankers, 
>> one ahead of the crystal roofing filters, one after them. Each has 
>> multiple tweaks. In contest conditions, I've found good noise 
>> reduction from using the one AFTER the roofing filter, and set for 
>> the greatest depth and shortest time. I THINK it's called the DSP 
>> Blanker.
>>
>> Yes, by their nature, NBs will modulate signals by the noise.
>>
>> Let's hope the NB in the K4 is better.
>>
>> 73, Jim K9YC
>>
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