[RFI] Can you identify this interference?

WX5L wx5l at charter.net
Thu Jan 22 18:20:55 EST 2004

Seems like your on to the source. If indeed the problem disappears when she
unplugs it I would attempt to convince her it may be defective causing the
radio trouble. You could ask her to return it for a replacement but the
replacement may also have the same trouble. It may be inherent in the
thermostat circuitry.

To really resolve the issue I would investigate other similar units that are
of well known brands, order one for her, ship it to your house, plug it in
and test it under your control. If it's noisy send it back until you find
one that's quiet.

How much is it worth having a quiet HF band these days? Plenty!  I'd pull
out some folding money to ensure that.


Subject: Re: [RFI] Can you identify this interference?

> I did a little DFing during lunch today.  With my ICOM R10 handheld RX,
> signal peaked about 17.4 Mhz.   I suspected the transformer, cable boxes
> between my back yard and neighbors yard, however I always had also
> something from inside the neighbors house.
> Well, with the IC-R10, the signal did not peak at the utiltiy boxes.
> However, it did peak at the back end of my neighbors house.
> Thank goodness shes a pretty nice old lady and works at the local gas
> station down the street.
> So, as mentioned before, I said this has been going on for 3 months or so,
> just never got around to it and suspected her house, so I never got bent
> of shape about it.
> So at the gas station, we chatted and I asked her if she had added in the
> last 3 or so months.....a scanner....no.....cable modem....no, any other
> electronics, tvs, radios, clock radios, telephones...no....electric
> blanket...no...BUT...oh in September I added an electric mattress pad for
> bed.  I asked is your bed at the end of the house by mine, yup.  Is the
> thermostat like one of those that has the neat little orange neon lamp to
> let you know its on...yup...
> So, shes going to call tonight and "unplug" to verify as well as give me
> manufactures brand name, model, etc.
> So, those of you on this reflector made me think to ask about electric
> blanket / heating pads....I recall a story or two where I read here about
> RFI from them.
> Now, those of you in the know, what can I do about it?
> Thanks and I will update for sure if this is the source.  Im 99.9% sure
> however.
> Alex, ask around.  Perhaps you will get a bite!
> 73
> Mike- KM0T
> ----- Original Message ----- 
> From: "Alex" <kr1st at amsat.org>
> To: <rfi at contesting.com>
> Sent: Thursday, January 22, 2004 6:57 AM
> Subject: [RFI] Can you identify this interference?
> > Hi there,
> >
> > Since a few weeks I've been plagued with this pulsating type
> > interference. I can receive the it from 12 MHz up to into the high VHF
> > range. So far I've found one very wide peak around 19-20 MHz (S9). I can
> > even see it on TV channel two (antenna, no cable) where it appears as 4
> > or 5 squiggly lines. Here's a sound sample:
> >
> > http://www.kr1st.com/interf.wav
> >
> > And the image of the recording made by Audacity can be found at:
> >
> > http://www.kr1st.com/interf.gif
> >
> > The recording is made with the receiver on 28.4 MHz USB.
> >
> > Any suggestions are greatly appreciated.
> >
> > 73,
> > --Alex KR1ST
> > http://www.kr1st.com
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