[Elecraft] K2 & Power Line Noise

[Johnny Siu]

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 <k.alexander at rogers.com>
收件人﹕ elecraft at mailman.qth.net; Larry Kendall <k5end at att.net>
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 <k5end at att.net> wrote:

> From: Larry Kendall <k5end at att.net>
> Subject: [Elecraft] K2 & Power Line Noise
> To: elecraft at mailman.qth.net
> 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
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