John,
The dead give-away is the frequency seperation of 15 khz. You are hearing the
horizonal sweep noise produced by a television(15.75 khz) in your close
proximity.
Often this sweep noise will couple with the cable and/or the electrical line
and radiate outbound. It depends on the manufacturer on the severity of the
problem. It could also be a poor cable connection aggravating this situation.
If the connections are good there's not much you can do about it but try and
choke the cable or electrical line with feritte core's. I have used mixture 77
with some success but it's hard to remove all traces of this wideband harmonic
of 15.75 khz produced by the TV.
With a portable shortwave receiver preferably with a SSB detector so it can
most resemble what you are hearing on your HF you need to hunt this TV down by
walking the street. Once you've focused down to a few houses then walk up to
the cable entrance or meter pan for closer inspection. You may need to collaspe
the telescoping antenna to detune the antenna as now this noise will be loud.
Once you've found the offending TV convincing the owner will be another
challenging which may be more difficult than finding it.
Good Luck,
Randy
WX5L
--
WX5L
Thibodaux, LA
---- W9RPM <john@w9rpm.com> wrote:
> Hi Larry,
> Yes it occurs on all HF receivers.
> It occurs on all antennas.
> Does not occur with antennas disconnected.
> Does occur on an HF mobile when I drive away.
> It is a carrier, wide band I would say. Almost like a
> buzzing sound.
> It is there about 80% of the time.
> Signal strength is constant when there.
> It is the strongest to the east of me.
> There are houses, a gas station, and Wal-Mart to the
> east/southeast of me.
>
> Thanks for asking the questions. Helped
> me explain it hopefully better. 73 John
> EMAIL: john@w9rpm.com
> WEBPAGE: http://www.w9rpm.com/
> AOL IM: W9RPM
> YAHOO: W9RPM
>
>
> ----- Original Message -----
> From: "Lefczik, Larry D" <larry.d.lefczik@lmco.com>
> To: "RFI" <rfi@contesting.com>
> Cc: <tvi-rfi-emi@mailman.qth.net>; "w1rfi" <w1rfi@arrl.net>
> Sent: Thursday, October 02, 2008 9:15 AM
> Subject: RE: [TVI-RFI-EMI] Noise every 15Khz on 17M
>
>
> >I think you need to provide more detail.
> >
> > Does it occur on all HF receivers in the shack?
> > Does it occur on all antennas?
> > Does it occur without an antenna connected to the receiver?
> > Does it occur if you take an HF receiver mobile and drive away form the
> > shack?
> > What do you mean by noise? Is it a carrier? Is it wideband white
> > noise?
> > It the interference there 24/7?
> > Is the strength constant?
> > What other info can you provide?
> >
> >
> >
> >
> > -----Original Message-----
> > From: tvi-rfi-emi-bounces@mailman.qth.net
> > [mailto:tvi-rfi-emi-bounces@mailman.qth.net] On Behalf Of W9RPM
> > Sent: Thursday, October 02, 2008 10:03 AM
> > To: RFI
> > Cc: tvi-rfi-emi@mailman.qth.net; w1rfi
> > Subject: [TVI-RFI-EMI] Noise every 15Khz on 17M
> >
> > HI, I am looking for some help on finding a noise that is up to s9+
> > every
> > 15Khz on 17M. The loudest is on 18125, then it drops off slightly every
> > 15Khz from 18125. Thanks- John W9RPM
> > EMAIL: john@w9rpm.com
> > WEBPAGE: http://www.w9rpm.com/
> > AOL IM: W9RPM
> > YAHOO: W9RPM
> >
> >
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> >
> >
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