[Elecraft] K2 noise blanker

[ka5oai]

Ron D'Eau Claire wrote:
> 
> One of the early Elecraft customers, Sverre Holm, LA3ZA, put
> together a wonderful page of K2 mods with links to the various documents.
> Check here for info about the KNB2:
> 
> http://www.qslnet.de/member/la3za/K2/modAny.html#KNB2
> 

on that page in the section about:
¤Increase time constants 
http://www.ac6rm.net/mailarchive/html/elecraft-list/2000-10/msg00086.html
http://www.ac6rm.net/mailarchive/html/elecraft-list/2000-10/msg00086.html 
 or here 
http://www.ac6rm.net/mailarchive/html/elecraft-list/2000-08/msg00040.html
http://www.ac6rm.net/mailarchive/html/elecraft-list/2000-08/msg00040.html 
are both 404 links

the gist of it said:
NB1: 10us ->70us
NB2:  70us->500us or 1ms
For electrical noise from motors, electrical fence etc
Increase C11 & C12
G3LUB
but I found no reference to values to change C11 &/or C12 to ???

after some digging I finally found the information here:
http://www.qsl.net/ve3mcf/elecraft_reflect/KNB2_Mods.txt



> Date: Wed, 04 Oct 2000 16:04:31 -0600
> From: Larry East <w1hue at ida.net>
> Subject: [Elecraft] Noise Blanker Observations
> 
> Thought I'd add my two (binary) bits worth to the NB discussion:
> 
> I find that my NB is very effective on an annoying popping sound (mostly
> on
> 80M) that I suspect is caused by an electric fence in the area. NB1
> reduces
> it considerably and NB2 removes it completely. I get similar results for
> certain types of static crashes: NB1 is somewhat effective and NB2 is very
> effective. However, neither seems to be too effective against electrical
> noise from drill motors, etc.
> 
> Back in August a couple of folks posted notes that they had increased C12
> on the NB board by a factor of 10 to 20 (thus increasing the blanking gate
> width to around 1-2 milliseconds) and got much better blanking of
> electrical noise. So I decided to give that a try.
> 
> Increasing C12 to 0.1uF definitely resulted in better attenuation (with
> NB2
> selected) of some types of electrical and atmospheric noise. However, it
> resulted in a rather raspy sounding CW signals. Backing off to 0.047uF
> worked just about as well on noise and did not produce any noticeable
> effects on signals.
> 
> As a result, I have made the following mod to my NB board:
> 
> 1. Changed C11 from 0.001uF to 0.0068uF (using the original C12 cap) to
> give an NB1 blanking pulse width of 65-70 us (instead of 10 us).
> 
> 2. Changed C12 from 0.0068uF to 0.047uF to give an NB2 blanking pulse
> width
> of around 500 us (instead of 70 us).
> 
> Seems to be a good overall compromise for the types of noise that I hear.
> Your results may vary.
> 
> 72/73,
> Larry W1HUE/7
> 


the root page was this one:
http://www.qsl.net/ve3mcf/elecraft_reflect/index.html#k2modas

maybe the above info will save someone else some time searching for the
info.


-----
73 & GB
KA5OAI
Sam Morgan
-- 
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