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K3 NB Generates noise

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Ed Stallman

K3 NB Generates noise

I finished K3 Kit 6644 yesterday and noticed today when using the NB
on 6m that it the NB will generate noise only on a few different
levels ! With NB Level on then DSP set to off .. I now turn
IF-NAR from off through the numbers 1 to 7 ...when I get to
IF-NAR 6 and 7 it is much noisier then 2,3,4, or 5 with 4 being
best ! Is this normal ? I was thinking the higher numbers would
reduce more noise ? Using IF-MID and WID 1 has more noise and 7 is less

Thanks Ed

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k6dgw

Re: K3 NB Generates noise

Ed,

First off, make sure you are running the latest production firmware. It
made some major improvements in the NB and NR functions.

The very nature of any noise blanker will distort the signal and using
it is a trade-off between that distortion ... which sounds a lot like
"noise" ... and the real noise mixed in with the desired signal. The NB
literally punches holes in the signal during noise pulses. As you go to
higher numbers, the blanker gets more aggressive, and typically, the
distortion increases.

The NAR, MID, and WID settings determine the width of the "holes." For
example, our electric fence periodically starts "ticking" when weeds
grow up under it in the spring. The noise pulses are very narrow, and a
NAR-1 or NAR-2 setting takes them totally out and does not introduce any
distortion that I can hear. A higher NAR setting seems to take them
out, but replaces them with the distortion from the holes in the signal,
which sounds a lot like the original noise pulses. :-)

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

On 7/18/2012 2:28 PM, Ed Stallman wrote:
> I finished K3 Kit 6644 yesterday and noticed today when using the NB
> on 6m that it the NB will generate noise only on a few different
> levels ! With NB Level on then DSP set to off .. I now turn
> IF-NAR from off through the numbers 1 to 7 ...when I get to
> IF-NAR 6 and 7 it is much noisier then 2,3,4, or 5 with 4 being
> best ! Is this normal ? I was thinking the higher numbers would
> reduce more noise ? Using IF-MID and WID 1 has more noise and 7 is less

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N5GE-2

Re: K3 NB Generates noise

In reply to this post by Ed Stallman

Noise blanker's on all rigs will cause distortion if set too aggressively,
especially on SSB. You've just found out about it ;o) Go back to where it is
best. Don't expect the NB to reduce atmospheric noise. It can't do that. The
NR is for that.

The numbers don't indicate how powerful the NB is. Some times the first setting
will be the best.

I'll leave it to someone else to give you the technical details.

Amateur Radio Operator N5GE
ARRL Lifetime Member
QCWA Lifetime Member

On Wed, 18 Jul 2012 16:28:36 -0500, Ed Stallman <[hidden email]> wrote:

>I finished K3 Kit 6644 yesterday and noticed today when using the NB
>on 6m that it the NB will generate noise only on a few different
>levels ! With NB Level on then DSP set to off .. I now turn
>IF-NAR from off through the numbers 1 to 7 ...when I get to
>IF-NAR 6 and 7 it is much noisier then 2,3,4, or 5 with 4 being
>best ! Is this normal ? I was thinking the higher numbers would
>reduce more noise ? Using IF-MID and WID 1 has more noise and 7 is less
>
>Thanks Ed
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html

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Guy, K2AV

Re: K3 NB Generates noise

In reply to this post by Ed Stallman

Hi Ed,

The IF NB in the K3 is a traditional noise blanker mechanism. It chops the
IF during signal peaks. It MUST modulate the other signals in the passband
when it is suppressing noise. Physics. I suggest you try all the DSP
varieties with the IF set to OFF. They do not have the artifacts that the
IF NB does. In general do not use the IF unless it's the only thing that
works.

Note that this modulation is quite worse when there is a signal inside the
roofing filter bandwidth that is not inside the DSP bandwidth, particularly
if you are listening to CW DSP with the SSB roofing filter. No way to get
around that without a CW roofing filter.

There is something around here that comes on that the DSP NB doesn't quite
get. I handle it (whatever it is) with DSP t1-7 and IF NAR 4. But the IF
setting still modulates other signals in the passband, because it has to.

73, Guy

On Wed, Jul 18, 2012 at 5:28 PM, Ed Stallman <[hidden email]> wrote:

> I finished K3 Kit 6644 yesterday and noticed today when using the NB
> on 6m that it the NB will generate noise only on a few different
> levels ! With NB Level on then DSP set to off .. I now turn
> IF-NAR from off through the numbers 1 to 7 ...when I get to
> IF-NAR 6 and 7 it is much noisier then 2,3,4, or 5 with 4 being
> best ! Is this normal ? I was thinking the higher numbers would
> reduce more noise ? Using IF-MID and WID 1 has more noise and 7 is less
>
> Thanks Ed
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Ed Stallman

Re: K3 NB Generates noise

In reply to this post by k6dgw

Fred , N5GE and Guy , Thanks all very good explanations and great
advice . I am using FW 4.51 and I believe it's good improvement . I
have the IF NB turned back and am hearing some weak signals on 6m .
just worked CT1HZE .

Ed

At 05:10 PM 7/18/2012, Fred Jensen wrote:

>Ed,
>
>First off, make sure you are running the latest production firmware. It
>made some major improvements in the NB and NR functions.
>
>The very nature of any noise blanker will distort the signal and using
>it is a trade-off between that distortion ... which sounds a lot like
>"noise" ... and the real noise mixed in with the desired signal. The NB
>literally punches holes in the signal during noise pulses. As you go to
>higher numbers, the blanker gets more aggressive, and typically, the
>distortion increases.
>
>The NAR, MID, and WID settings determine the width of the "holes." For
>example, our electric fence periodically starts "ticking" when weeds
>grow up under it in the spring. The noise pulses are very narrow, and a
>NAR-1 or NAR-2 setting takes them totally out and does not introduce any
>distortion that I can hear. A higher NAR setting seems to take them
>out, but replaces them with the distortion from the holes in the signal,
>which sounds a lot like the original noise pulses. :-)
>
>73,
>
>Fred K6DGW
>- Northern California Contest Club
>- CU in the 2012 Cal QSO Party 6-7 Oct 2012
>- www.cqp.org
>
>On 7/18/2012 2:28 PM, Ed Stallman wrote:
> > I finished K3 Kit 6644 yesterday and noticed today when using the NB
> > on 6m that it the NB will generate noise only on a few different
> > levels ! With NB Level on then DSP set to off .. I now turn
> > IF-NAR from off through the numbers 1 to 7 ...when I get to
> > IF-NAR 6 and 7 it is much noisier then 2,3,4, or 5 with 4 being
> > best ! Is this normal ? I was thinking the higher numbers would
> > reduce more noise ? Using IF-MID and WID 1 has more noise and 7 is less
>
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html