[Icom] TV and receiver noise

Thu, 27 Jun 2002 07:39:45 -0400

You didn't mention what type of noise you're hearing, but I'll guess that
it's white or broadband noise.  I have a 36" RCA which radiates broadband
noise all the way up to 28 MHz (not bad on 80, 40).  I've spent a lot of
time on this one, and found some other hams with the same problem with the
large screen RCA sets.

The problem originates in the switching power supply.  In most cases, this
supply is on all the time, not just when the picture is on, so the remote
control circuitry can respond to a "power on" command.  In my case, the
amplitude of the noise was the same whether the CRT was on or off.  I can
look down into the rear of the set and see inside the switching supply - no
shielding at all as you'd see when a switching supply is used is
communications gear.  Much of my noise was emanating from the TV itself, but
some was being radiated by the power cord and the audio-in cables.  Radio
Shack split ferrite chokes made a difference on those cables, but
substantial noise was left.  I was able to reduce the noise just about to
the receiver noise floor by using an MFJ 1026 noise canceling unit.  In
order to pick up adequate noise signal in the sense antenna, I had to place
a small dipole (total 4 feet) fed with RG-174 a foot or so below the TV.
After playing with that configuration for a day or so, I finally installed a
remote control appliance switch so that I can now turn off the TV completely
from my operating position.  Obviously, not a good solution if others want
to watch TV or if the noise is coming from next door.

Early one morning, I went to the TV/appliance store where I bought the RCA
and discussed the problem with their repairman.  He understood completely,
but said he'd never heard of any other complaints.  He contacted RCA factory
service and they claimed ignorance of the problem.  I went back to the store
another day, armed with a portable shortwave receiver and demonstrated the
problem to them.  I checked several different brands, and the Toshiba sets
appeared to radiate much less of the broadband noise, but this test required
turning off every other set in the room.  Normally, there would be 20-30
large screen sets all plugged in at one time.  So, unless you have a VERY
cooperative store manager who's willing to spend the time unplugging all the
sets, this approach isn't going to help you.  One thing for certain - the
RCAs are death when it comes to this problem and should be avoided at all
costs.  Too bad because they really have a nice picture.

K8AC
Floyd Sense in Angier, NC

----- Original Message -----
From: "John Geiger" <[email protected]>
To: <[email protected]>; <[email protected]>;
<[email protected]>; <[email protected]>
Sent: Wednesday, June 26, 2002 9:55 PM
Subject: [Icom] TV and receiver noise

> Here is a problem that I have not seen discussed
> before.  In our living room we have a GE 27 inch,
> picture in picture TV.  When it is turned on, the
> noise level on 30 thru 12 meters jumps to S5 to S6.
<snip>....