Inverted V multiband dipole... mounted in the attic?

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wbswetnam

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I appreciate everyone's help and advice in getting me started in amateur radio. OK, my next antenna question. Is it possible to place an inverted V multiband dipole inside the attic of a house with a 30 degree pitch? The landlord doesn't like the idea of an outdoor antenna but is willing to let me place what I want in the attic. Neither the roof nor the siding of the house is made of metal. I'm thinking of having a 20m element (which works out to about 16.4' for each radial), a 15m element (10.9' per radial) and a 10m element (8.5' per radial). It should be fairly easy to suspend the whole thing from the roof supports, suspend the center balun from the apex, then run the coax down to the radio room immediately below. Is this a pipe dream or is this a feasible design?
 

davenlr

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Just remember there is electricity going through the antenna. If you put it in the attic, make sure it is totally away from wood, and well insulated on the ends.

I had an 80m dipole mounted in an attic of an apt building when I first got my license back in the early 70s, and while tuning it up, the SWR went from 1.3:1 to 6:1. I went up to see what happened, and the corona at the end of the antenna had started the wood on fire, melted the wire, and it had fallen to the floor. Ive NEVER put another transmitting antenna inside the house. Your landlord might want to reconsider his decision.
 

wbswetnam

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I'm not planning to get an amp so I will be running barefoot, no more than 100W. Does that make a difference to the threat of spontanious combustion?
 

davenlr

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Well, that all depends on the band you use, and how well the radio is grounded. They have corona balls on even low power CB antenna whips, and I am not an expert on it, so Ill just say keep the ends of the antenna away from anything flammable :)
 

popnokick

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At 100 watts or less on the input of the antenna, you are not likely to have a heating problem with an inverted-V that you described.... cut to proper lengths, good coax, and appropriate insulators. Outside the building is always better, but in the attic is better than no antenna at all. Ensure you have a good tuner as well. And pay attention to your grounding system.
 

AgentCOPP1

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Yeah only thing I would say (like the other poster mentioned) is to keep the ends insulated. I was tuning my vertical once and accidentally touched the end of a radial. It was hot as hell, like touching a stove. Good thing I didn't burn myself though... that's what reflexes are for lol. I don't think they would have the exact same effect on wood but RF can potentially burn wood if you're unlucky enough, so just keep those babies insulated.
 

wbswetnam

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Thanks. Yeah, it's looking more and more like I will have to go with something mobile, either in the car or a "backpack" survivalist-style unit that I can take someplace, set up and use. (sigh) Oh well hopefully someday I'll have my own house out in the country and I can do as I like.
 
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