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Author Topic: "UPDATE" Please help 6 meter question  (Read 265 times)
W7DXN
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Posts: 6




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« on: March 09, 2002, 09:54:36 PM »

First of all I would like to thank each and everyone who contributed to my problem solving of my new 6 meter station getting into my neighbors TV.  After spending much time today trying to solve the problem I finally took my TV over to her house and GREAT NEWS. She said she couldn't even hear a scratch when I keyed up using my TV. I tried another one of my TV's and it also worked fine. I put hers back in line and she could hear every word I was saying.
Now what do I do? Is there something going out in her TV? I guess I could go out and buy her a HPF capable of covering up to the 6 meter band. Is this going to be an instant fix or will I just be throwing my money away? I really don't want to go out shopping and buy her a new TV but, if it came down to that I probably would.
It sure sounds like fundameantal overload- the cause of 99% of 6M TVI. I was going to buy a LPF for my station but I feel that it  will have no effect as my rig is most likely not emitting harmonics- if it were, the TVI would show up only on those channels harmonically related to 6M- CH11 eg.
I might add that I had my son walk around and check with my other neighbors while I was testing and no one else had any problem what so ever.
I know some people will say to heck with her, it's her problem but I couldn't live with myself and enjoy my hobby if it came down to that.
Thanks in advance for your valuable advice, I really appreciate it.
73
Bill       W7DXN
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AC5E
Member

Posts: 3585




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« Reply #1 on: March 09, 2002, 10:19:55 PM »

Hi: The first thing I would do is disconnect her antenna/cable/whatever and short the input. Then try transmitting. If she's still got a problem it can only be coming in on the power line or is picked up directly. The directly is a problem. I know some people who have had good luck spraying a conductive paint all over the inside of the cabinet, but it has not helped for me. Otherwise there's not much you can do about it.

  If it's coming on the power line, try a clamp on ferrite, with as many turns as possible, as close to the set as possible.

But if there is no TVI with the beasties input shorted, try taking two of the 300 ohm to 72 ohm baluns hooked end to end (it does not matter whether you use a short piece of RG6 on the coax ends or hook the 300 ohm wires together) in line with the antenna. That quite often stops common mode front end overload.

Hope that helps

73  Pete Allen  AC5E
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KC9AZL
Member

Posts: 250




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« Reply #2 on: March 09, 2002, 10:20:27 PM »

I think you can buy a high pass filter for your neigbors tv.  Good luck getting rid of the TVI.  
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K0CBA
Member

Posts: 295




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« Reply #3 on: March 10, 2002, 01:01:22 AM »

I've been on and off 6 since the Gonset AM days; talk about TVI!!  You already have received good advice and will undoubtly receive more but I have one non-technical suggestion,  NEVER, NEVER, NEVER "lay hands upon" someone's TV.  For the duration of eternity everything that will ever go wrong with it, the stereo, the toaster, the sink drain, etc., will be your fault.  "It didn't do that before you ...(fill in the blank)".   I know it's sometimes hard to not dive in and help but trust me on this one. Remember, 'No good dead goes unpunished' and this act of helping kindness will come back to bite you in the butt everytime.  K0RIR (SK) had a slick set up, he had a little TV that was modified to be almost a TVI filter with a picture tube; absolutly bullet proof.  With someone operating his station he would set it on the complainant's TV. His TV was perfect while the complainant's TV was jumping up and down.  He'd look at it, unplug his TV and say, "yup, you have a problem".
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AC5E
Member

Posts: 3585




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« Reply #4 on: March 10, 2002, 11:16:59 AM »

Chuckle: The Gonset mention brings back memories for me also - and having spent a good chunk of my life in the TV business I agree that it is not generally desirable to open up anyone's TV unless it's by a paying customers request. It is pretty certain that you will get the blame for anything that happens to it from that day forward, back, and sideways.

It's generally OK to try things external to the set when the TVI sufferer is cooperative and when you explain things before you start. Let's try this in the antenna and see if it helps, or let's try putting the AC cord through this interference filter, is generally safe when you get cooperation. You and the TVI sufferer are on the same page - trying to get the problem solved without a lot of hassles.

But IF the sufferer knows the TVI problem is in her TV, and IF you can show her that the problem is coming through the box itself and not through the power line or antenna, AND IF YOU LET HER SEE EVERYTHING YOU DO and tell her the reason why, you may be able to get away with it.

I have just never found anything you can do with the back off that did the first bit of good! That includes conductive paint and even glueing aluminum foil over every square inch of solid cabinet and back.

73  Pete Allen  AC5E
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