[Elecraft] Intermod filter for the KX3

Sun Jun 3 16:11:43 EDT 2018

Thanks Nick for that info, I have a lot of power lines all around this apt
building and I have wondered if a lot of the noise is coming from that.
I like the idea of turning the power off, and locating the source of
noise... at least then you have the satisfaction of knowing where it is
coming from or what it is.
73's Mike AB7RU

On Sun, Jun 3, 2018 at 11:13 AM, Nicklas Johnson <nick at n6ol.us> wrote:

> Second that.  I have one external power supply from a well-known ham-gear
> manufacturer of somewhat questionable repute which throws off S9 racket all
> over everything, or did until I gave the output cord about 10 turns through
> a hefty ferrite.
>
> I'd forgotten about the RX Shift feature being per-band somehow... it could
> be my imagination but it seems to take down the omnipresent 30Hz impulse
> noise a few dB at my QTH in San Mateo.  (I've of course gone through
> turning off power to the house and driving around in portable operation...
> I think the problem is generally being anywhere near PG&E transmission
> lines, which is something that's hard to avoid anywhere in the SF
> peninsula.  The noise blanker also does a pretty decent job of suppressing
> it even further.)
>
>    Nick
>
> On 3 June 2018 at 10:45, Mel Farrer via Elecraft <elecraft at mailman.qth.net
> >
> wrote:
>
> > Wayne,
> > You missed one.  Depending on operation whether it is internal battery or
> > external supply.  I have had problems with a lot of external source, so
> > always put a dummy load on the antenna a see if the noise is conducted or
> > radiated.  Just one more reason to go solar/battery in the field.
> Yummmm.
> > Mel, K6KBE with KX3 is all applications
> >
> >       From: Wayne Burdick <n6kr at elecraft.com>
> >  To: Mike Parkes <mspmail2 at gmail.com>
> > Cc: elecraft at mailman.qth.net
> >  Sent: Sunday, June 3, 2018 10:15 AM
> >  Subject: Re: [Elecraft] Intermod filter for the KX3
> >
> > Mike,
> >
> > What you’re describing sounds like noise that is in-band and would be
> > debilitating for any radio. Not intermod. But just to be sure, set
> MENU:RX
> > SHFT to 8.0 and turn off the noise blanker. This is the most resilient
> > setup if you have monster signals actually causing IMD.
> >
> > Also try turning off the preamp.
> >
> > If the above steps don’t help, you could simply have a case of very high
> > noise floor. Here are a few more things you can try:
> >
> > 1. Use very narrow filter bandwidths. In CW mode, use the APF feature
> > (audio peaking filter).
> >
> > 2. Move the antenna farther from identified noise sources.
> >
> > 3. Try a magnetic loop. These are very narrow banded, and may have
> > directional characteristics you can make use of.
> >
> > If all else fails, try taking your KX3 portable as an experiment. A
> > location far from massive noise sources can be a breath of fresh air,
> both
> > atmospherically and ion-ically. It’s not a long-term solution unless,
> like
> > me, you discover that field operation is a blast. But it’ll give you some
> > perspective about your noise at home.
> >
> > 73,
> > Wayne
> > N6KR
> >
> >
> >
> >
> >
> > ----
> > http://www.elecraft.com
> >
> > > On Jun 3, 2018, at 9:49 AM, Mike Parkes <mspmail2 at gmail.com> wrote:
> > >
> > > Hey group
> > > I have an issue here and am wondering if a good band pass filter would
> > > help? I pick up so much sqawks and buzzing weird interference, grating
> > > machine sounds, on my KX3 on all HF bands, it is horrible in my setting
> > > (ground floor apartment in the city). I have the same issues on 2 meter
> > > handhelds, noise all over the band, trips the squelch making it nigh
> > > impossible to scan without the radio stopping on some ghost signal that
> > is
> > > only intermod. Same story with the KX3 2 mtr module though I can turn
> the
> > > squelch up enough to keep the radio scanning without stopping on noise
> > for
> > > the most part. Is there any hope for HF? Would some sort of HF band
> pass
> > > filter help my KX3? Or is the filtering in the KX3 already good
> enough? I
> > > can't make it go away with the built in KX3 noise filters. There is
> this
> > > one company across the street from me, some internet megalith place
> with
> > > sat dishes on the roof and I wonder if some of the noise is coming from
> > > that establishment. Anyway... thanks for any ideas... head for a park,
> a
> > > mountain peak... I know... :)
> > >
> > > 73's Mike AB7RU DN17gp
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>
> --
> *N6OL*
> Saying something doesn't make it true.  Belief in something doesn't make it
> real. And if you have to lie to support a position, that position is not
> worth supporting.
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