[RFI] Need Help With RFI Problem with Neighbor

E. Hajjar E. Hajjar" <ejh3@erols.com
Tue, 23 Nov 1999 08:05:50 -0800

Hi Jon,
If you really want to know the full extent of the interference I would
1. Run at the maximum power you use - I assume 1000W
2. On every ham band you use have someone transmit in the CW portion of the
     and then  transmit in the SSB portion of the band. (Frequency used and
mode make a difference)
3. While a transmission is going on, and at your neighbors house use the
remote control
     and surf through every channel and record the interference level on
each channel. I would use
    3 interference levels: Severe - can't watch TV channel; Moderate - can
still watch the program but  quite
    annoying; Mild - it's obvious someone is transmitting but only someone
very petty would complain.
4. After you have done the first three steps you'll probably be surprised at
how few interference problems
    you notice. You can then lower the power to 100W and just check the
channels/bands where you
    noticed interference. This will give you a very good idea of the true
extent of the interference problem.
5. With a TA-33 you would want the beam pointed directly at the neighbors
house especially if they have
    an outside TV antenna. There is a 10DB difference between 100W and
1000W. Depending on the
    direction of the beam there can be a difference of 25DB over a 360
degree rotation.
6. If the neighbor is using an outside TV antenna then you would expect
interference to be on channels
    2,3,4,5,6. If the neighbor is using Cable TV and you notice interference
on every channel then the TV
    is being overloaded - but Cable TV signals are 100 times larger than a
regular TV signal. It is very
    difficult to 100% eliminate TVI when someone is using an outside TV
7. I suspect it would take about 2 hours of testing to get a complete
picture of the interference problem.
    You could make a template with a list of all channels and then make a
copy of the template for
    each band. This way you'll have a separate sheet to record the
interference levels for each band.
    On some bands you'll probably notice no interference at all.
8. After that you can try filters, torroids and etc. to see if you can
eliminate the problem. The big concern
    is if you install anything and 6 months later the TV malfunctions you
can easily get blamed for
    breaking the TV. The neighbor could say the TV never worked quite right
after you put that filter on.
    When I was a teenager and everyone had an outside TV antenna I remember
noticing that one lead
    of 300 ohm twinlead was not connected to the back of a TV set of a
neighbor. I used a screwdriver
    and re-connected the wire and the TV picture then was nice and clear.
Many years later I learned
    that the neighbor's TV failed some time after that, I was blamed as a
kid who tried to be helpful but
    broke the TV in the process. The ARRL recommends that hams don't install
filters and etc. on
    a neighbor's equipment because it's so easy to get falsely blamed.

Jon, if you know the full extent of the interference problems then you'll
have options when operating in
a contest. I know most interference problems show up on 20 meters and 10
meters. I know most hams
just give their neighbor advice or perhaps a HighPass Filter but being a
good ham and a good neighbor
requires making a 2-3 hour effort to see if the problem can be solved or at
least reduced to a tolerable
level so that you can enjoy ham radio and your neighbor can watch their TV.

Good Luck and 73,
Ed - K1MMI

----- Original Message -----
From: Jon Ogden <jono@enteract.com>
To: <rfi@contesting.com>
Sent: Monday, November 22, 1999 9:03 AM
Subject: [RFI] Need Help With RFI Problem with Neighbor

> Hi all,
> Well, yesterday I was having a blast during my first phone SS and making a
> nice run at accomplishing my goal of 1000 Qs.  I was at about 765 around
> 5:15 pm local time when I heard (and felt) a banging at my door.  It was
> neighbor.  I was killing his TV, his stereo and possibly other stuff.
> Anyhow, I have had problems with this guy before.  He's very understanding
> and is not an ass about it or anything.  His uncle was a ham so he's
> somewhat familiar with the stuff.  I first realized he was picking me up
> after this year's WPX contest.  He said I was getting in his TV.  I was
> getting in mine too!  So I asked around and everyone said to use some
> torroids and make common mode chokes.
> I did this to my TV and stereo first and pretty much cleaned up my stuff
> completely.  I then wrote up an explanation of how to wrap cords around
> cores and then took that with a couple of cores and stuck them in his
> mailbox.  I told him that we may need to also put cores on his stereo and
> other equipment and that if he had any problems to let me know.
> Well, I'd heard nothing since last spring, so I thought all was OK.  Now
> says I am still getting into his TV which doesn't make sense.  I don't
> I am getting into the cable system.  I can watch TV in the shack and have
> problems.  Perhaps he's gotten a new cable box or VCR.
> Anyhow, what's the best way to deal with this?  I am not sure which
> give him fits or what power levels.  So I thought of the idea of having
> another ham at my station transmit on various frequencies and power levels
> while I am at my neighbors house.  I could take my torroids in with me and
> clean up everything all at the same time (I think if I put torroids on all
> of his TV cables, power cords, speaker cords, etc. I'll be OK).  But
> have told me to make him install the stuff and not to install anything
> myself.  I know it's technically not my problem, but I want to do what I
> anyhow.  I am willing to pay for all the torroids, filters, etc.  I also
> figured I would get him literature from the FCC and ARRL.

> The guy is really cool about it and wants to find a solution so that I can
> operate and he can watch TV and listen to the stereo.  I pretty much went
> QRT last night as I didn't want to accidentally aggravate the situation.
> Most of the time there isn't a problem as he and his wife are rarely home
> when I am home.  But weekends and contest weekends in particular are a
> problem!
> I also don't know if I could be the source of the problem.  My beam is a
> Mosley TA-33.  I have no balun on it, just a coil of coax of 13 turns
> 10" in diameter.  My gut tells me my feedline is radiating or something
> is causing interference since that antenna gives me most of my problems.
> It's on a roof tower about 14 feet above the roof and about 35 to 40 feet
> above the ground.  My neighbors house is about 50 to 75 feet away.  He
> happens to be to the east of me which is where I was pointing when he came
> over.  I don't know if feedline radiation from the beam would cause any
> RFI problems to him than the beam itself.
> I have a homebrew 4-1K amp that I run at legal limit. I have an ICE
> filter and also use an antenna tuner most of the time.
> Anyhow, what's the best approach to take with this guy.  My first attempt
> fixing the problem "partially" fixed it, but I don't want to make any more
> attempts.  I want to get it fixed and have it be that.  Of course, I think
> he thinks the problem is with my stuff.  I guess the most ideal situation
> would be to move out of the neighborhood and buy a house with many acres
> no neighbors nearby.  I wish I could, but that's not practical.
> Any help, including some "local" elmering from anyone in my area
> IL) would be appreciated.
> Thanks es 73,
> Jon
> --------------------------------------------------------------------------
> The Second Amendment is NOT about duck hunting!
> Jon Ogden
> jono@enteract.com
> www.qsl.net/ke9na
> "A life lived in fear is a life half lived."
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