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 Are Satellite TV LNBs Immune to .... 
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Post Are Satellite TV LNBs Immune to ....
Are satellite TV LNBs immune to HF?

I'm just deciding where to route my wire for 80/40/30. The best place for the 'skyhook' is the gutter-line about 5 feet above my satellite dish.

It's the usual Astra job, recently installed, with posh co-ax, and has the usual stock LNB/Downconverter.

Given the massive separation of frequencies, has anybody ever had problems?

Thank 'ee kindlee

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Tue Nov 13, 2012 7:53 pm
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 Are Satellite TV LNBs Immune to .... 
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Post Re: Are Satellite TV LNBs Immune to ....
It might be a problem, the reason I say that is because my installation the TV downlead was only about 6 feet from my antenna and without realising it the feeder was about 60 feet long, which is a half wave on 40 Mtrs and I was getting terrible trouble with RF getting into the TV system. Anyway, to cut a long story short, I pulled the TV lead out the back of the telly while the TX was keyed and promptly got quite a nasty RF burn on just 100 Watts.

I cured it by placing 6 ferrite clamps in the middle of the 60 TV feeder where maximum current was, thereby splitting the feeder in half, that removed the high RF voltage off the ends of the feeder completely and I've never had a problem since. So just expect the unexpected and be prepared.

It's a wonder the high voltage RF didn't burn out the internal capacitors in the TV system :scratch:

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Tue Nov 13, 2012 8:52 pm
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 Are Satellite TV LNBs Immune to .... 
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Post Re: Are Satellite TV LNBs Immune to ....
Thanks for that. Good point. I would never have thought of the entire downlead length being a problem.

Fortunately (?) my house is pretty small, so even on 30m the TV downlead will only be at most 1/3 wave long. Also I only usually run about 20-25 W, and the antenna will be roughly perpendicular to the downlead.

So, nobody has had any problems with LNB-swamping or picture-freezing then?

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Tue Nov 13, 2012 9:08 pm
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