[Elecraft] Alligators

[Bob Nielsen]

I find the noise reduction function of the KDSP2 to be quite helpful  
under noisy (non-impulse) band conditions.

Bob, N7XY

On 12/01/03 14:19:26, Ron D'Eau Claire wrote:
> Good points, Jim, but WHY run the pre-amp on 80? The K2 has a noise
> figure
> way, way below the band noise on even a short piece of wire on 80
> meters
> without the pre-amp.
> 
> The pre-amp is needed to pull really weak signals up above the
> receiver
> noise floor on 15 or 10 meters, but it shouldn't be needed below  
> that.
> 
> 
> The K2 noise blanker is effective against clear 'impulse' noise (like
> a few
> cheap lamp dimmers in my neighborhood) and that is one place where I
> will
> occasionally turn on the pre-amp on the lower bands. Sometimes, even
> on low
> threshold, the pulses don't trigger the NB unless I boost everything
> with
> the pre-amp. Then the pulse noise drops out even though the overall
> noise
> floor is much higher than needed. Still, it improves copy.
> 
> The noise blanker, because it is a non-linear device literally
> "chopping
> holes" in the received signal can also add "noise" of it's own in the
> form
> of an increased background level.
> 
> Ron AC7AC
> 
> -----Original Message-----
> Subject: [Elecraft] Alligators
> ...it's also important to remember that many guys are stuck with some
> pretty
> high noise levels. That's my problem on 80 and 40 -- my dipole at 45
> ft sees
> an S8 on 40 and S9 on 80 with crystal filter set to use the SSB  
> filter
> and
> the preamp on. Of course I can pull that level down a lot by going to
> narrower bandwidths, but the noise level generates a lot of ringing
> due to
> the filter slopes.  Signals were quite good on 40, especially Friday
> night,
> so I was able to work a lot of DX on that band in spite of the noise.
> But I
> could only hear a few of the stongest DX signals on 80, and made only
> about
> 25 QSO's there.
> 
> For all practical purposes, the noise blanker in my K2 does nothing  
> at
> all
> with this noise. The blanker in my Omni V is somewhat effective,
> sometimes
> reducing it by a couple of S-units. When I have time, I'm going to
> experiment with an active antenna noise canceller that I bought on
> EBay.
> 
> Jim Brown
> K9YC
> 
> 
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