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Author Topic: Vertical Antenna interfering with neighbors over the air tv broadcast?  (Read 832 times)

N8CHR

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I have a 4 band vertical antenna, ground mounted with radials located about 40 feet from neighbors roof mounted over the air tv broadcast antenna? I have only been xmitting on 40, 17 and 20 meters at approx 70 watts and only digital FT8. Neighbor says he can tell when my xmitter is keyed and it only last a couple seconds. I just read the over the air freq. are in the VHF and UHF as they always were. IIf I put a low pass filter on my xmitter should that elminate,? my problem. Any other suggestions?
Thanks
Tom N8CHR
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W9IQ

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What model of transmitter/transceiver are you using, Tom?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

K4FMH

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I have a 4 band vertical antenna, ground mounted with radials located about 40 feet from neighbors roof mounted over the air tv broadcast antenna? I have only been xmitting on 40, 17 and 20 meters at approx 70 watts and only digital FT8. Neighbor says he can tell when my xmitter is keyed and it only last a couple seconds. I just read the over the air freq. are in the VHF and UHF as they always were. IIf I put a low pass filter on my xmitter should that elminate,? my problem. Any other suggestions?
Thanks
Tom N8CHR
Tom,

A cheap tool for you is to buy the same OTA antenna that your neighbor has and install it temporarily on the side of your house nearest your neighbor's antenna. Feed a TV with it in your house. See if it causes interference on YOUR OTA TV signal. If not, then I'm not sure it's your signal. That's a cheap way to begin the diagnosis.

And, are their any false positives? I.e., they report "seeing" your signal when you're actually not transmitting? It could be something in their house instead.

Good luck..

Frank
K4FMH
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KA1CNK

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It's possible.  If for some reason the transmitted harmonics are strong enough, a low pass filter could help.
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AB3MO

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Check SWR on the bands that you operate.  Are you sure that the antenna bands are tuned for a good match at the operating frequencies?  Is the feed line in good shape, no loose connections, and you have a good ground.  Keep in mind that the neighbor has a responsibility as well: could the TV set be using a an "SDR" type of tuner that could easily be overloaded?????  I am not impressed with the "SDR" radio in my newish car!  Probably the worst AM/FM auto receiver I have ever seen!!!!
    Dave
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K6AER

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Your problem is probably RF overload on your neighbors device. You said they were only forty feet away. What is the device your neighbor is using.This is a case for snap on toroids.

When I moved to Colorado I put up a 4 element SteppIR beam at 105 feet. Every neighbor knew there was a ham in the area, I did not hook it up to any equipment. For about a week several neighbors knocked on my door to complain about interference. I walked them to the side of the house and showed my coax coiled on the ground next to the tower. A older ham told me to do this when I put up the tower and it was good advice.
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WA9AFM

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Offer to have a technician check the neighbor's feed line and the antenna.  He might have the "Walmart Special" coax/antenna or it might have been damaged by birds, critters, or weather.

However, I do lean to the simple RF overload especially if the neighbor's antenna is pointed at yours.
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NA4IT

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These new fangled digital TVs get interference from everything. My wife can turn her mixer on and kill ours. She can cut my hair with the Wahl clippers and kill it. Hate to say itm you may be fighting a loosing battle here. Good luck.
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N2QLT

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A low pass filter certainly won't do any harm. Or you could move to the middle of nowhere like I did 23 years ago. I was crawling under a neighbor's computer desk winding a choke when he muttered "I don't know why I have to live this way". That was it. 40 acres now, and I do as I please. Although, broadband internet would be nice....
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W2JUV

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Tom, another idea may be to connect any type of indoor TV antenna to your TV and then transmit on all bands you normally use and see if there is any effect. A basic indoor bow-tie type or rabbit ears might be good enough, assuming you are close enough to broadcast stations to get a picture on your TV.
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N8CHR

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W9IQ
Glenn I'm using a kenwood TS480 and running only FT8 right now. I thought Hi Def was using some other higher then thou frequencies not just the old VHF and UHF. I put an old drake low pass filter on yesterday just to see what I would get. Almost no power out and out of sight SWR. I think there may be a problem with the filter, it's at least 40 years old. Don't know. Been wanting to get a new one. So I'm going to get a new low pass filter, common mode choke and make one solid run of RG 8. I have snap on filters on everything. I've been at this for over 40 years, not going to let an old neighbor shut me down.
Glenn thanks for your advice. I'll keep you inform. I've been building an 813 amp for quite a while thought I would finish it, we'll see. Thanks again Also want to get my DX 60 back on the air
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KG4RUL

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When wiring a house for 'cable', builders are notorious for using the absolute, cheapest coax that they can lay their hands on.  In some cases, this cable is so poorly shielded that there is no way to prevent front-end overload, short of replacement of the offending cable.

I would suggest that under no circumstance do you touch any of your neighbor's TV equipment.  If you do, you may find yourself being hounded for anything that goes wrong in the future.  Even your paying for a technician may create a future liability.  Make suggestions but maintain your distance.
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KH6AQ

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I have only been xmitting on 40, 17 and 20 meters at approx 70 watts and only digital FT8. Neighbor says he can tell when my xmitter is keyed and it only last a couple seconds. I just read the over the air freq. are in the VHF and UHF as they always were.

That this occurs on three bands indicates it is probably not harmonic related. However, adding a low pass filter is an easy experiment. The MFJ-704 LP filter is $110 at DX Engineering.

If it is fundamental overload any ferrite treatment at the neighbor's house must be effective on the 80 meter band. That pretty much precludes single turns thru clamp-on ferrites. Multiple turns can work. The lowest cost and most effective ferrite treatment could be 17 turns of the output cables together thru an FT240-31 core. The AC cord can be wrapped on its own core and because 17 turns will not fit I would wrap as many turns as will fit on one core then as many turns as will fit on a second core. The neighbor's might have limited patience and throwing everything at it to begin with could speed things up.

Four FT240-31 cores are available at DX Engineering for $57.   https://www.dxengineering.com/parts/dxe-tc31-24-4

 
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W3WN

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What type of antenna is the neighbor unsung on the affected TV set?

Are any other sets in the neighbor’s home affected?

Are any other neighbors affected?

How close is the antenna to the neighbor’s home?  And the affected set?
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W9IQ

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The comment that "it only lasts a few seconds" brings to mind that it isn't the ~15 second FT-8 transmission that is causing the problem but only the beginning of the transmission. You say you are running about 70 watts - what radio are you using and how are you limiting the output power to 70 watts?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.
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