[TenTec] Computer noise in radio

[Cook, Thomas A]

A quick try to check out your monitor to see if shielding will help is to
temporarily wrap it in alum. foil (+ the cable) and ground it to the 'puter
case.  Don't leave this on very long - heat will rapidly build up.

Watch out for "aquadag" paint - it *may* tend to flake off and short
something out.  Miller-Stephenson Chem. Co. used to sell a nickle based
conductive paint.  Also, check out   <http:tecknit.com>.  They sell
conductive epoxies as well as other EMI products (no, I don't have any of
their stock).

Anyone having success in this area, please post it.  It is a way too common
problem that (sometimes) a "higher quality" monitor may cure, but no
guarantee.  Another problem is 'puter cases that have minimal shielding
(especially on the front).  On this note, I have seen cases where the
cover-case junction is covered with paint.  Nice, huh?

One last note, be wary of any digital indicators that indicate the processor
speed (e.g., "133") - they often are a source from which emi may be
radiated.  

Tom - WA2BPE

> ----------
> From: 	J. Pursley[SMTP:kf5mc@flash.net]
> Sent: 	Wednesday, September 30, 1998 9:35 AM
> To: 	Carl Hyde
> Cc: 	Bob Ensminger; tentec@contesting.com
> Subject: 	Re: [TenTec] Computer noise in radio
> 
> 
> Another method is to go to a TV or electronics parts dealer and see if he
> has any
> aquadag spray or paint. Use it the same way as described below. It should
> work
> better.....joe
> 
> Carl Hyde wrote:
> 
> > Your monitor is probably of a late design that did not have to meet the
> more
> > stringent FCC emitted noise specifications that older monitors and
> computers
> > had to meet.  The computer industry was successful in watering down the
> FCC
> > requirements just to annoy Ham operators.  So what can you do?  Well one
> > approach I have used is to open the monitor and remove the plastic case
> > completely.  Spray the complete inside of the case and back with zinc
> chromate
> > paint.  Use a strip of copper foil with conducting adhesive to ground
> the zinc
> > chromate coating to the chassis ground.  Then wrap the power cord and
> the video
> > cable into a large toroid or use a snap-on toroid to eliminate noise on
> those
> > cables.  I have used this method and have also made a mu metal shields
> for the
> > inside of the monitor case.  The paint method is effective and easier.
> Hope
> > that helps.
> >
> > Bob Ensminger wrote:
> >
> > > I would appreciate info on how to get rid of computer noise in HF
> radio.  I
> > > have a new 17" screen for a computer I built up.  When I disconnect
> screen
> > > the noise goes away.  What can I do to filter noise(ie S-7 at various
> > > places on ham bands) from getting into radio?
> > >
> > > My other monitor from the other computer close by does generat some
> but
> > > hardly noticeable.
> > >
> > > Thanks for help,
> > >
> > > Bob, KQ7J
> > >
> > > --
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> > carl.s.hyde@lmco.com
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> >
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> "Tics"
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> >
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