[RFI] Tough to solve TVI problem

michael.findley at ni.com michael.findley at ni.com
Fri Jun 6 07:35:53 EDT 2003

That sounds like the creators of your TV did not use proper grounding
technics. Take the back cover off and check out the ground wires that tie
the shields together. Make it short as possible and put a large ferrite on
the wires to the tube. I used this to fix a few monitors from Samsung
during the 96 CE Mark madhouse. The frequency range I tested was from 26MHz
to 1000GHz at 3V/m CW with 80% AM 1kHz.
(Embedded image moved to file: pic01869.gif)

                      "Bob Tellefsen"                                                                                            
                      <n6wg at earthlink.n        To:       "N6KJ" <kelly at thejohnsons.ws>, <rfi at contesting.com>                     
                      et>                      cc:                                                                               
                      Sent by:                 Subject:  RE: [RFI] Tough to solve TVI problem                                    
                      rfi-bounces at conte                                                                                          
                      06/05/2003 07:29                                                                                           

You didn't say outright, but it sounds like you are feeding
your antennas with coax.
1.  Do you have a balun at the antenna?  If not, can you add one
2.  Can you feed the antenna with 300 ohm twinlead as a
balanced-line experiment?  I ask because I cleared my TVI years
ago by going to a totally balanced antenna system.
Hope this gives you an idea or two.
73, Bob N6WG

-----Original Message-----
From: rfi-bounces at contesting.com [mailto:rfi-bounces at contesting.com]On
Behalf Of N6KJ
Sent: Thursday, June 05, 2003 5:14 PM
To: rfi at contesting.com
Subject: [RFI] Tough to solve TVI problem

I have a 10 year old Mitsubishi 35" CRT TV, model number CS-35201.
I am getting TVI on both 40 and 80 meters.  Both dipoles are about 30 feet
above the TV.  On 40 meters, I get interference with as little as 5 watts
TX output.  On 80 meters, I get interference with as little as about 20
The rig is clean and has a low pass filter on the output.  The TV has an AC
line filter and ferrite beads on all inputs.  I get interference on all
channels regardless of input source (satellite rcvr, DVD, VCR) or input
jack (S-Video or 75 ohm rf input).  Normally, I only use the S-Video input.
I have tried grounding the rig to an 8 ft. long ground rod and leaving it
floating and there's no change.  The rig should be clean.  It is an
FT-1000MP and just came back from Yaesu service with a clean bill of
As best I can tell, the interference is
coming right through the chassis and getting into the video circuitry.

Does anyone know of any particular issues with Mitsubishi or this
model?  Any suggestions of what to try next?  I can't even get a service
technician to work on this.  I've called several service technicians and
insist there's nothing they can do about it.  Mitsubish won't acknowledge
it could be a TV problem either.

Has anyone found a TV manufacturer that manufacturers "clean" tv's and/or
understands these types of issues?  I'll make a more informed choice next
time around :-)
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