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 Another balun question 
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Post Another balun question
Hi,
Just need advice on 1:1 balun for 450 ohm feeder. I have made a 1:1 current balun to a picture I found on the net, could you point me in the right direction.
Just to make sure I have the right design.
I have a 120ft doublet with 46ft of 450ohm feeder, the doublet is in a U shape to fit in the garden.
The balun will just have 5ft of coax then at the end of the 450 in the shack.
Thanks for any pointers.
Terry

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Terry,
MW0ZUS


Mon Aug 12, 2013 4:04 pm
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 Another balun question 
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Post Re: Another balun question
Terry,

What bands? And what power?

Steve G3TXQ


Mon Aug 12, 2013 4:08 pm
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 Another balun question 
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Post Re: Another balun question
Sorry forgot to mention that :-) mainly 80,40,20. But interested in 17, 15m as well but don't think its very efficient on the warc bands as its about 90 and 100 ohms on them, not far from 50 ohms on all the rest, 60ohms on 40m 47ohms on 80m, on the analyser.
Thanks,

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Mon Aug 12, 2013 6:30 pm
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 Another balun question 
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Post Re: Another balun question
Power?

Steve G3TXQ


Mon Aug 12, 2013 7:54 pm
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 Another balun question 
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Post Re: Another balun question
Power is 50w, using ts830s but plug in reverse polarity 9v into alc with a 220k pot,as no variable power on these old rigs.
Its a real 50w with my licence.

Thanks Steve,
Terry

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Mon Aug 12, 2013 8:34 pm
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 Another balun question 
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Post Re: Another balun question
OK, then I'd use 12 bifilar turns on an FT240-31 ferrite core. Each wire can be the inner conductor plus dielectric stripped from a length of RG58. Something like this:

Image

But note that the one in the photo has 8 turns, so you need 4 more.

73,
Steve G3TXQ


Mon Aug 12, 2013 9:45 pm
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 Another balun question 
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Post Re: Another balun question
Thanks Steve,
I had made the exact of the photo, will re do with 12 turns.
Thanks for your help.
Terry

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Tue Aug 13, 2013 6:00 am
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