[CW] Strange interference

[Ken Burrows]

Nothing very scientific done for my tests, but a quick check with my Kenwood
TS 570D in the CW position
showed QRM from my cable modem very loud on the
80 meter freq. first 40 meter freq, and the first 20 meter
freq. I couldnt hear anything on the 10 M freqs..

When I unplugged the cable modem power the above freqs went clear...

Could it be a near by cable modem that is QRMing you??

My cable modem is a Motorola  SB4101 Surfboard model, it is very dirty....as
is my CPU monitor and the
computer itself...

73

VE1DS

----- Original Message ----- 
From: "Donald Chester" <k4kyv at hotmail.com>
To: <cw at mailman.qth.net>
Sent: Saturday, January 01, 2005 1:44 AM
Subject: [CW] Strange interference


> This interference covers the entire HF spectrum - from 80m to 30 mHz, 24/7
> for the  last couple of months.  It is spaced intervals of approximately
> 30.475 kHz.  On an AM detector it sounds like a tone modulated carrier,
but
> careful observation shows that there are two distinct carriers
heterodyning
> against each other; one is unmodulated and the other has a spastic but
> barely perceptible frequency shift of a few Hz, and each shift initiates
> with a click. The frequency shift averages about twice a second.
>
> The higher in frequency, the greater the spacing of the carriers.  At 30
> mHz, they are a little over 800~ apart, on 20m. they are a little over
400~
> apart, on 40 they are 200+ hz apart, and on 80m about 100~ apart.
Although
> the signals appear approximately every 30.475 kHz, some frequencies are
much
> stronger than adjacent ones.  There are a few holes in the pattern, where
> nothing is audible on the expected frequency.
>
> The signal appears to be local, since it comes in on 10m all the time, and
> the S-meter remains stationary, thus excluding  the liklihood that it is
> skywave.  The higher in frequency, the stronger the signal.  It is louder
> than my xtal calibrator on 10m, but on 80m it is almost buried in the
noise.
>
> Here are a few of the frequencies I measured that  fall inside the ham
> bands:
>
> 29.998826/29.999660 mHz
>
> 14.884912/14.885340 mHz
>
> 7.373734/7.373935 mHz
>
> 3.618225 kHz
>
> The signal is extremely stable; I notice no drift over a 24-hour period.
>
> It is not something in the house, since I cut the a.c. power at the main
> utility entrance and the signal is still there.
>
javascript:PopUp('http://www.qrz.com/ib-bin/ikonboard.cgi?s=bb184a566cd996d8
331f5b3e57a1cd05&act=Legends&CODE=emoticons','HelpCard','200','400','0','1',
'1','1')
> Emoticons
> Anyone ever heard anything like this?
>
> Don K4KYV
>
>
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