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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Hello Steve,

I am thinking of putting a dipole for 10/15/20 in my loft i may have the space to put it in the
inverted v shape but it will not be a v it would be a ( flatter v ) i hope that makes sense I would need to do this on order to get the antenna in at 7.2 meters I may also just run short of space by a couple of feet .
I have measured the floor space and it is 22ft 9in so may get the 24ft 3in in the V shape but if not would it still work if i had to put the last foot or so along the floor at each end or would it be better to put the last 2 feet or so of the cold side along the floor .

this is the antenna i am thinking of steve

http://www.moonraker.eu/Amateur-Radio/W ... IRE-DIPOLE

I hope the question makes sense Steve.

Regards Frank G4YLJ

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Fri Jan 06, 2012 2:46 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
So the antenna is 7.4m long and you've got a 6.934m (22ft9) wide space to put it?

If you've got a 6ft loft space (1.82m) that gives you a total length of wire of 7.831m to go between the top and the eves.

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Fri Jan 06, 2012 2:57 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Actually doing the trig if you have 6ft as a heigh you're going to have a 62deg angle instead of the desired 60deg angle.

Sounds like you could be sorted!

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Fri Jan 06, 2012 3:04 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Hello Chris ,

Well I cannot stand up in my loft and i am 5ft 8ins lol i had to buy the smallest 2/70
co-liner to get in there i cannot get up there just yet to measure it .
So depending on the thoughts given I will measure it but it is a job getting up there
nowadays lol .

de FRANK G4YLJ

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Fri Jan 06, 2012 3:33 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Any rough idea of height?

Even if the roof was only 1.3m tall you'd still fit it in but the angle would be 70deg instead of 60deg

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Fri Jan 06, 2012 3:39 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
after getting annoyed with a pen and paper on my desk I googled and found you this

http://www.carbidedepot.com/formulas-trigright.asp

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Fri Jan 06, 2012 3:40 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
HANG ON CHRIS I WILL GET THE LADDERS !!!!!

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Fri Jan 06, 2012 3:43 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Either way you've probably got enough room as long as you've got 4ft 3!

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Fri Jan 06, 2012 3:53 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Bloody hell i had forgot how small it was up there just measures it and i have 4ft 2in of head room
only its not easy working up there but if i can get a antenna that will work on 10/15/20 it will be worth it lol

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Fri Jan 06, 2012 3:55 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Looks like i should be ok then Chris lol thanks for the help :beg: :beg: :beg: :clapping:


DE FRANK G4YLJ

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Last edited by G4YLJ on Fri Jan 06, 2012 3:57 pm, edited 1 time in total.



Fri Jan 06, 2012 3:56 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
It looks like you might be lucky, once you've looked at the trig. If not, you can certainly bend the last couple of feet - I'd try to keep it symmetrical and do the same at each end. Because it's a trapped dipole, what you do at the ends will only affect the 20m SWR.

73,
Steve G3TXQ


Fri Jan 06, 2012 3:56 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Hello Steve ,

Well it looks as though i might be very lucky i will get one and try it it has got to be better
than what i have at the moment i do ok on 2/70 with the co-liner i will let eveyone know how i get on with it .. :beg: :hello:

DE FRANK G4YLJ

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If you sometimes feel a little useless, offended or depressed...
Always remember that YOU were once the fastest and most victorious little sperm out of millions...


Fri Jan 06, 2012 4:01 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Well it'll be a tight squeeze but it'd fit just.

You might need to bend the legs of it a tad too.

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Fri Jan 06, 2012 4:18 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
At the risk of slowing you down, another option might be to string up a cobwebb,- lofts were made for these- you need 8ft square, put a couple of crossed bits of poundland washing line into an 'X' for the frame and hang the elements on that wih cable ties - 5 bands, one feeder and you aren't doing some crazy limbo into the eaves to stretch out the ends of a dipole. there's enough on this forum and the web in general to pick Steve's plan or original speaker wire version. Mine works ok (maybe 20m a bit tricky to tune...?), indoor dipoles as a comparison are about the same, one feeder wins it

mine is strung around a VHF beam stub mast in the loft - the 2m tonna is not too pleased...but still workable.

73

dave


Fri Jan 06, 2012 4:24 pm
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 TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE 
Silent Key

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Post Re: TRAP DIPOLE IN THE LOFT ANTENNA NOT ALLOWED OUTSIDE
Dave,

Good call! Depending on the geometry of the loft, the Cobweb might fit in without too much loss in height compared to the Inverted-V; in fact, with some roof materials you might get away with the Cobweb being tilted so that the max current sections are kept high against the roof .... if that makes sense?

73,
Steve G3TXQ


Fri Jan 06, 2012 4:34 pm
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