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KNB2 - looking for experience with mods that made it effective

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Stan AE7UT

KNB2 - looking for experience with mods that made it effective

I just recently built the KNB2 and it does not seem to be very effective for the noise pulses near my house.
I also put a the KNB1 in my K1 with disappointing results.
I'm comparing this to my K3 and KX3 that almost completely eliminate the noise.

Doing some internet research there appears to be a couple of mods that people embrace.
I was looking at LA3ZAs site and he shows two mods.

Any advice before I start slinging solder?

Thanks
Stan AE7UT

Don Wilhelm-4

Re: KNB2 - looking for experience with mods that made it effective

Stan,

First check the KNB2 to be certain it is working. With no antenna on
the K2 and the preamp on, tap a metallic object (screwdriver) against
the case of Q21 - you should hear clicks (ignore the 'rushing' sound of
the screwdriver acting as an antenna). Turn on the NB and the clicks
should be reduced - you may have to switch it to Low Threshold.

Once you verify that the KNB2 is working, you can proceed with the
mod(s). Most have found that increasing the value of C11 is sufficient
- solder another .001 uF capacitor across the leads of C11 as a test (or
a permanent solution).

A caution, those mods may not be effective against the type of noise you
have. The KNB2 works quite well on impulse noise like automotive
ignition noise, but does not work well with noise sources with a slow
rise time. The KNB1 is similar (the K3 NB is different). The KNB2 will
do nothing to reduce powerline noise or the noise from various household
appliances.

If the KNB2 cannot handle your particular noise source, you may have to
add the KDSP2 with its Noise Reduction algorithm which is effective on
such things as powerline noise.

73,
Don W3FPR
On 10/9/2013 5:06 PM, Stan AE7UT wrote:

> I just recently built the KNB2 and it does not seem to be very effective for
> the noise pulses near my house.
> I also put a the KNB1 in my K1 with disappointing results.
> I'm comparing this to my K3 and KX3 that almost completely eliminate the
> noise.
>
>
> Doing some internet research there appears to be a couple of mods that
> people embrace.
> I was looking at LA3ZAs site and he shows two mods.
>
>

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Stan AE7UT

Re: KNB2 - looking for experience with mods that made it effective

Thanks Don and Ron.

I checked the NB and it appears to be working fine.
I added the .001 and didn't notice any significant change in the pulsing noise I'm hearing.

I wish I could show a screen shot from my P3. There are multiple large swaths of pulsing
S9+ RF in this rural town. I do live about 3 miles from a power plant with large electric lines
about a mile away. I've never really gone out and tried to pin down the noises. Sounds like
a job for the KX3 on a lonely night. In between the patches of noise it's VERY quiet.
My glass is half full!

Thanks for the help.

73
Stan AE7UT

Don Wilhelm-4

Re: KNB2 - looking for experience with mods that made it effective

Stan,

As I indicated, slow rise time noises (like powerline noise) will not be
squelched by the KNB2 nor the KNB1. They will work on fast rise time
noise pulses like from auto ignition noise or lightning, but will not
work on continuous noise sources like powerline noise.

The KX3 (and the K3) handle the NB function differently, and in many
instances can be effective for powerline or household appliance noise.
For the K2, the only cure may be with the KDSP2 Noise Reduction algorithms.

73,
Don W3FPR

On 10/9/2013 7:20 PM, Stan AE7UT wrote:

> Thanks Don and Ron.
>
> I checked the NB and it appears to be working fine.
> I added the .001 and didn't notice any significant change in the pulsing
> noise I'm hearing.
>
> I wish I could show a screen shot from my P3. There are multiple large
> swaths of pulsing
> S9+ RF in this rural town. I do live about 3 miles from a power plant with
> large electric lines
> about a mile away. I've never really gone out and tried to pin down the
> noises. Sounds like
> a job for the KX3 on a lonely night. In between the patches of noise it's
> VERY quiet.
> My glass is half full!
>
>

k6dgw

Re: KNB2 - looking for experience with mods that made it effective

Or electric fence noise. Fence chargers pulse a couple of KV at roughly
1 per second give or take a half-second. When weeds grow up under the
wire [they ALWAYS do :-)], the arc from the wire to the weed is a very
short, fast rise-time pulse.

I have an electric fence. The weeds grow for me about as good as for
everyone else, leaving me two choices: Walk the fence line through all
the brush and weeds and fix the arcs, or let the NB take the noise out
which it does very effectively, it just disappears and there are no
audible artifacts in the rest of the audio.

OTOH, power line hash is a lot different [I have that too, the 69KV tie
line between two hydro plants runs across the S end of the property],
and when I get the NB to suppress "some" of it, the audio gets pretty
raucous with all the holes being punched in it.

Nothing is perfect.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org

On 10/9/2013 4:36 PM, Don Wilhelm wrote:
> Stan,
>
> As I indicated, slow rise time noises (like powerline noise) will not be
> squelched by the KNB2 nor the KNB1. They will work on fast rise time
> noise pulses like from auto ignition noise or lightning, but will not
> work on continuous noise sources like powerline noise.

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riese-k3djc

Re: KNB2 - looking for experience with mods that made it effective

In reply to this post by Stan AE7UT

Sounds like Plasma TVs,,,, I have one local that pretty messes up
stuff around 3820 and it drifts ,,, put together a small loop and try to
DF it

Bob K3DJC

On Wed, 9 Oct 2013 16:20:43 -0700 (PDT) Stan AE7UT <[hidden email]>
writes:

> Thanks Don and Ron.
>
> I checked the NB and it appears to be working fine.
> I added the .001 and didn't notice any significant change in the
> pulsing
> noise I'm hearing.
>
> I wish I could show a screen shot from my P3. There are multiple
> large
> swaths of pulsing
> S9+ RF in this rural town. I do live about 3 miles from a power
> plant with
> large electric lines
> about a mile away. I've never really gone out and tried to pin down
> the
> noises. Sounds like
> a job for the KX3 on a lonely night. In between the patches of
> noise it's
> VERY quiet.
> My glass is half full!
>
> Thanks for the help.
>
> 73
> Stan AE7UT
>
>
>
>
> --
> View this message in context:
>

http://elecraft.365791.n2.nabble.com/KNB2-looking-for-experience-with-mod
s-that-made-it-effective-tp7579755p7579758.html

> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
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dmb@lightstream.net

Re: KNB2 - looking for experience with mods that made it effective

In reply to this post by Don Wilhelm-4

Just a few observations regarding NR and NB, from an op at a QTH that is
at times plagued by powerline noise:

Since the KDSP2 provides Noise Reduction (NR) as opposed to Noise Blanking
(NB), the best that it can do with *any* noise is to make it easier on the
ears. It will not however drop the noise floor that may be covering up a
weak signal. I have never heard any NR on any radio that was capable of
doing that, and have never seen it have any effect on the S-meter or the
noise floor as observed on a panadapter. However, the Noise Blanker has
the potential to actually drop the noise floor (as observed on both the
S-meter and panadapter), revealing signals that would otherwise have been
completely masked.

I have both the K3 and K2, and the K3's Noise Blanker is the very best
that I've ever used on any radio, including several SDR radios, and it was
one of the primary reasons that I bought a K3 after having borrowed one
from a friend. I have had instances here where the S-meter on the K3 reads
S9 on 10 meters from powerline noise, and engaging the NB -completely-
eliminates the noise and the s-meter drops to S0 or S1, revealing signals
that were otherwise completely inaudible. Engaging the NR in this case
didn't drop the S-meter at all, and did nothing to reveal the signals that
were covered up by the powerline noise.

That said, I still find the K3's NR to be effective, but again, only to
reduce listening fatigue. Unfortunately, I've never heard NR from any
radio render a signal copyable with NR engaged, that would not be copyable
with it disengaged.

Just my $0.02 worth...

73, Dale
WA8SRA

> Stan,
>
> As I indicated, slow rise time noises (like powerline noise) will not be
> squelched by the KNB2 nor the KNB1. They will work on fast rise time
> noise pulses like from auto ignition noise or lightning, but will not
> work on continuous noise sources like powerline noise.
>
> The KX3 (and the K3) handle the NB function differently, and in many
> instances can be effective for powerline or household appliance noise.
> For the K2, the only cure may be with the KDSP2 Noise Reduction
> algorithms.
>
> 73,
> Don W3FPR
>
> On 10/9/2013 7:20 PM, Stan AE7UT wrote:
>> Thanks Don and Ron.
>>
>> I checked the NB and it appears to be working fine.
>> I added the .001 and didn't notice any significant change in the pulsing
>> noise I'm hearing.
>>
>> I wish I could show a screen shot from my P3. There are multiple large
>> swaths of pulsing
>> S9+ RF in this rural town. I do live about 3 miles from a power plant
>> with
>> large electric lines
>> about a mile away. I've never really gone out and tried to pin down the
>> noises. Sounds like
>> a job for the KX3 on a lonely night. In between the patches of noise
>> it's
>> VERY quiet.
>> My glass is half full!
>>
>>
>

OE5CSP-Chris

Re: KNB2 - looking for experience with mods that made it effective

In reply to this post by Stan AE7UT

In the August issue of Germans´s "Funkamateur" there was an article about this topic.I´ll keep the article short:
He measured L3 and found out that it had 80µH(he built it correctly according to the manual) instead of 40µ Henry.
So I also swapped L3 but my noise blanker was still doing nothing against the cow fences. In an e-mail he suggested replacing C12 to22nF.I haven´t done this modification yet, but I´ll do it. Our alpine meadows are full of cows at the moment and I mainly use the K2 for my portable operations, so´ll be glad to get a hint
73,Chris-OE5CSP