How to completely stop TV interference.

OldskoolPirate · Post by **OldskoolPirate** » Tue Oct 11, 2016 3:52 am

Anyone know how to transmit right next to or sometimes mounted on top of a regular tv antenna ?
Maybe using a balun ? For dipoles or Would using a 1/4 wave gp fix the problem ??

Albert H · Post by **Albert H** » Tue Oct 11, 2016 7:13 am

Your rig needs to be truly clean - any harmonics or wideband noise will cause problems, so you need to check that the rig on a spectrum analyser.

Get your antenna well above the TV aerial - the more separation, the better.

Use an aerial that doesn't radiate downwards - a groundplane type is best.

Best of all - find somewhere else to mount your aerial!

shuffy · Post by **shuffy** » Tue Oct 11, 2016 3:54 pm

Regarding your point about the balun - yes, obviously good practice to ensure that the coax isn't radiating! If using a dipole, you should be using some kind of match in any case. As Albert said, a ground plane will be best IMO.

Also, If the TV in question is your own, you could also put a high pass filter in line. Or, is it on a block for example, where the TV antenna feeds a DA (distribution amplifier)?

yellowbeard · Post by **yellowbeard** » Tue Oct 11, 2016 4:05 pm

Also if there is a masthead amplifier on the antenna the signal from the transmitter will overwhelm it causing everything that passes through it to mix together into mush. I hope we have convinced you to try another way.

Maximus · Post by **Maximus** » Wed Oct 12, 2016 12:30 pm

Yep, what yellow beard said. Doesn't matter how clean your rig is. If you're putting out a lot of power, the it's just going to swamp the tv tuner and any amps along the way.

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pirateaddict · Post by **pirateaddict** » Thu Oct 13, 2016 7:19 am

How to stop TV interference... Chop the TV tx aerials down

Maximus · Post by **Maximus** » Thu Oct 13, 2016 10:23 am

pirateaddict wrote:How to stop TV interference... Chop the TV tx aerials down

I stayed briefly at Crystal Palace 20 years ago and the transmitters were right next to me. All I could hear through my Walkman was a loud buzzing noise whilst trying to listen to DJ Cool.

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pirateaddict · Post by **pirateaddict** » Thu Oct 13, 2016 12:36 pm

OK Maximus.. How the hell did ya cope with that? I wouldn't know where to start tbh. I'd have to go for a walk or something... Fantasy and Scr in Sheff used sprogg all over the fm band in me mate's flat int same block lol. That was wierd and just thought it was coz we were so near the aerial, never knew about dirty rigs back then, I bet it were a right pain up ont 15th floor though.

Albert H · Post by **Albert H** » Thu Oct 13, 2016 6:26 pm

The funniest TV interference I was ever party to was from a medium wave rig, into a Tower-Block Sloper on 576kHz. What we'd forgotten was that VHS video recorders use frequencies around there for their colour information.... Everyone in the block got psychedelic video recordings!

I got a phone call from a friend who lived there, warning me about the problem, so I got him to go upstairs and unplug the rig. Eric Gotts and Brian Garlic were entering the block as my friend went to the phone box to call me back! G&G left empty-handed since they weren't even sure if that whopping great signal was coming from there. I moved the rig up to 846kHz and shortened the aerial and the reinstalled rig lasted for a several months up there.

Maximus · Post by **Maximus** » Thu Oct 13, 2016 8:38 pm

Haha love hearing the stories of Gotts leaving empty handed. Bit before my time luckily so I guess I was lucky.

I only stayed at Crystal Place for 5 days. We stayed at the sports ground and were literally a stones throw away from the tx. Open the curtains and it's smack bang in front of you.

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yellowbeard · Post by **yellowbeard** » Thu Oct 13, 2016 9:12 pm

I feel a bit bad because it's been all "Oh noooooooooo" and not really offered any help.
A high pass filter and/or braid breaker on the TV coax may help.

Code: Select all

http://www.qsl.net/g4lna/pages/braidbkr.html

An odd number of quarter waves spacing between the antennas starting at 3/4 wave is an amatuer radio trick, and a good low pass filter on the transmitter is absolutely necessary. TVI can sometimes be cured by putting a ferrite clamp on the coax at the back of the TV, that is the best case you could hope for. If the TVI is caused by the overdriving of the TV input stage or the aerial masthead amp then the only cure is lower transmitter power and/or greater separation between the antennas. Ham radio sites like qsl.net and dxzone.com have sections on interference, some of them are running kilowatts from a semi detached in suburbia.
You may have a problem that is not cureable, that is why there are no straight answers here, and why it has devolved into anecdotes about TVI that were nightmares at the time but seem funny after a few years.

evieacme · Post by **evieacme** » Wed Nov 09, 2016 10:38 am

Maximus wrote:Haha love hearing the stories of Gotts leaving empty handed. Bit before my time luckily so I guess I was lucky.

I'm an assistant producer at a TV production company called Acme Films (please feel free to check out our website: http://acmetv.co.uk/) and we're currently developing a documentary that will be a history of pirate radio.

I was wondering if anyone had any information on Eric Gotts (DTI) and whether you have any contact details for him or his family?

Any help much appreciated!

Many Thanks,

Evie