[R-390] powerline noise - it's dead, I've killed it!

Sun, 6 Apr 2003 18:26:39 -0700

Many of you might not know that 100 Base Ethernet is a spread spectrum
signal source with a differential voltage swing of several volts into 100
Ohms, in other words, several milliwatts, with a (catch the big words here)
Power Spectral Density ranging from 300kHz to over 65MHz. If there is any
non-linearity in the circuitry or the isolation transformers, or the twisted
pair wiring, the differential (non-radiative) quality can be degraded into
common mode and the CAT5 cabling radiates. Terry just saw BigFoot.

Bob

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Terry O'Laughlin
Sent: Sunday, April 06, 2003 6:09 PM
To: [email protected]
Cc: [email protected]
Subject: [R-390] powerline noise - it's dead, I've killed it!

I want to thank everyone for their suggestions on finding my horrible noise
generator.  And Dave Maples gets a big thanks for his right on the money
suggestion.  Today was the perfect day to tackle his suggestion because I
had to rest all the clocks anyway.

I found the noise generator and it was not some marginal piece of junk.  It
is a one year old Linksys 100 Base-T, 4 port hub.  This thing spent the
eight months of it's life three feet from my receiver rack.  I'm going to
complain to the manufacturer otherwise I'd take it out in the street and
drive over it with my VW microbus for the sheer satisfaction of hearing the
case shatter.  I guess the foil FCC Part 15 sticker was not big enough to
do it's job.

I am so relieved.  I was ready to give up on the SW/MW/LW bands as a
hobby.  My present QTH is still noisy, but not the S9 to +20 noise I've had
for the last year.  It really made me wish I was still in the farmhouse in
Barneveld, WI set on a narrow ridge of iron bearing sandstone and yielding
European LW broadcasters several times every winter (on a 40 meter dipole
used as a T no less).

Thanks again,
Terry O'
WB9GVB

At 19:22 2003-3-26 -0500, you wrote:
>Terry: First, I think I'd check to see if my own house was in order. If you
can drop power to your entire house, do that with the Sony on batteries and
see if the spur goes away. If it does, then restore power and drop breakers
one at a time till you find the offending circuit, then go figure out what
equipment is causing the problem.

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