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K2 & Power Line Noise

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L Kendall

K2 & Power Line Noise

I'd like to get some opinions on the K2 audio filter options.

In last year's mobile QSOPs running with the K2, the power line and similar noise were show stoppers in some areas.

I've already ordered the K2 noise blanker and am also considering one of the 2 audio filter choices. As this K2 will be used for mobile contesting, I can't see me fiddling with complex menus in real time during a mobile run. So, I'm not sure what the best choice is for me.

So far I've used the K2 for CW only and CW is my primary need for noise abatement.

Can someone who has had CW experience with the K2 AF option(s) and NB for wideband/pulse noise interference provide an opinion?

I'm also curious just how much more effective the KDSP2 is than the KAF2 for reducing interference.

Thanks,
Larry
K5END
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Ken Alexander-2

Re: K2 & Power Line Noise

Hi Larry,

My K2 is equipped with the KDSP2 and I'm happy with it's ability to reduce noise. I haven't used the KAF2 but I just completed building Elecraft's AF-1, which I am told is similar.

That said, the only unit that has noise reduction capability built into it is the KDSP2. The KAF2 is an audio bandpass filter. It will reduce noise somewhat by virtue of narrowing the audio bandwidth, but that's a side benefit of narrower filters (you get the same effect by selecting a narrower crystal filter, XFIL).

The KNB2 noise blanker is effective at reducing impulse noise and it has several options that are easily changed from the front panel, all with the same button as a matter of fact.

The KNB2 won't get rid of "wideband" noise. That's where the KDSP2 comes in. The KDSP2 will also soften the sound of a CW note, making it sound kind of "mushy" and most of the time it's worth it to dig out a station buried in the mud.

The basic functions of the KDSP2 are handled with three front panel buttons. Along with noise reduction, the KDSP2 also gives you four audio bandwidth filters (AFIL) for each mode in addition to the four XFIL bandwidths. The KAF2 only gives you two. Some people prefer the sound of the KAF2 over the KDSP2, but if your objective is noise reduction then my opinion is that the KDSP2 is the way to go.

Hope that helps a bit.

73,

Ken Alexander
VE3HLS

--- On Mon, 1/10/11, Larry Kendall <[hidden email]> wrote:

> From: Larry Kendall <[hidden email]>
> Subject: [Elecraft] K2 & Power Line Noise
> To: [hidden email]
> Date: Monday, January 10, 2011, 1:42 PM
> I'd like to get some opinions on the
> K2 audio filter options.
>
> In last year's mobile QSOPs running with the K2, the power
> line and similar noise were show stoppers in some areas.
>
> I've already ordered the K2 noise blanker and am also
> considering one of the 2 audio filter choices. As this K2
> will be used for mobile contesting, I can't see me fiddling
> with complex menus in real time during a mobile run. So, I'm
> not sure what the best choice is for me.
>
> So far I've used the K2 for CW only and CW is my primary
> need for noise abatement.
>
> Can someone who has had CW experience with the K2 AF
> option(s) and NB for wideband/pulse noise interference
> provide an opinion?
>
> I'm also curious just how much more effective the KDSP2 is
> than the KAF2 for reducing interference.
>
> Thanks,
> Larry
> K5END
> ______________________________________________________________
> 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
>

Johnny Siu

K2 & Power Line Noise

Hello larry,

First of all, I do not have the experience of line noise in VR2. However, I
used / built both KDSP2 and KAF2 in the past.

Although KDSP2 has more features, I would consider KAF2 more value for money.
Bearing in mind, you can get a KAF2 in the second hand market at nearly half
price.

I once used KDSP2 but sold it later because I was annoyed by its artifact no
matter how I adjusted the denoiser settings. Earlier K3 also experienced the
same issue but it is now much improved after the latest firmware updates.

Both KAF2 and KDSP2 are in the audio stage. I would consider the DSP in KDSP2
is primitive when compared with the modern rigs. You cannot compare KDSP2 with
the DSP in K3 because they are of different generations - day and
night difference in terms of design theory and performance.

I got my KAF2 at some $45 after I sold my KDSP2. For such a small sum of money,
I got an internal clock + some filtering and considered it a value for
money investment.
cheers,

Johnny VR2XMC

________________________________
寄件人﹕ Ken Alexander <[hidden email]>
收件人﹕ [hidden email]; Larry Kendall <[hidden email]>
傳送日期﹕ 2011/1/11 (二) 3:38:28 AM
主題： Re: [Elecraft] K2 & Power Line Noise

Hi Larry,

My K2 is equipped with the KDSP2 and I'm happy with it's ability to reduce
noise. I haven't used the KAF2 but I just completed building Elecraft's AF-1,
which I am told is similar.

That said, the only unit that has noise reduction capability built into it is
the KDSP2. The KAF2 is an audio bandpass filter. It will reduce noise somewhat
by virtue of narrowing the audio bandwidth, but that's a side benefit of
narrower filters (you get the same effect by selecting a narrower crystal
filter, XFIL).

The KNB2 noise blanker is effective at reducing impulse noise and it has several
options that are easily changed from the front panel, all with the same button
as a matter of fact.

The KNB2 won't get rid of "wideband" noise. That's where the KDSP2 comes in.
The KDSP2 will also soften the sound of a CW note, making it sound kind of
"mushy" and most of the time it's worth it to dig out a station buried in the
mud.

The basic functions of the KDSP2 are handled with three front panel buttons.
Along with noise reduction, the KDSP2 also gives you four audio bandwidth
filters (AFIL) for each mode in addition to the four XFIL bandwidths. The KAF2
only gives you two. Some people prefer the sound of the KAF2 over the KDSP2,
but if your objective is noise reduction then my opinion is that the KDSP2 is
the way to go.

Hope that helps a bit.

73,

Ken Alexander
VE3HLS

--- On Mon, 1/10/11, Larry Kendall <[hidden email]> wrote:

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
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Help: http://mailman.qth.net/mmfaq.htm
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L Kendall

Re: K2 & Power Line Noise

In reply to this post by L Kendall

Thanks to all who responded, both publicly and privately. The good and
useful information is exactly what I need.

73
Larry
K5END

On Mon, 2011-01-10 at 12:42 -0600, Larry Kendall wrote:

> I'd like to get some opinions on the K2 audio filter options.
>
> In last year's mobile QSOPs running with the K2, the power line and similar noise were show stoppers in some areas.
>
> I've already ordered the K2 noise blanker and am also considering one of the 2 audio filter choices. As this K2 will be used for mobile contesting, I can't see me fiddling with complex menus in real time during a mobile run. So, I'm not sure what the best choice is for me.
>
> So far I've used the K2 for CW only and CW is my primary need for noise abatement.
>
> Can someone who has had CW experience with the K2 AF option(s) and NB for wideband/pulse noise interference provide an opinion?
>
> I'm also curious just how much more effective the KDSP2 is than the KAF2 for reducing interference.
>
> Thanks,
> Larry
> K5END
> ______________________________________________________________
> 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

Michael Babineau-2

Re: K2 & Power Line Noise

In reply to this post by L Kendall

Larry :

I installed the KAF2 in my K2 about 1 month ago and have played with it a lot.
What I have found it does allow me to do in many cases is to turn off the K2 preamp
and still being able to copy weaker signals.

In general the AF1 and AF2 settings on the KAF2, in addition to the active audio filtering,
add back a little bit of extra gain to compensate for the losses induced by the IF filter in the narrower positions.

There is also a low pass audio filter that is always in the audio chain (at least in CW mode) to reduce
high frequency hiss but its' effects are most noticeable on a fairly quiet band.

I can't compare with the KDSP2, but I am happy with the performance KAF2 considering its' price.

It sounds like maybe you need the noise reduction capabilities of the KDSP2.

Michael VE3WMB / VA2NB

--- On Mon, 1/10/11, Larry Kendall <[hidden email]> wrote: