[Elecraft] K2 & Power Line Noise

[Ken Alexander]

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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