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PA2WIV > TECHNI 23.02.04 14:07l 60 Lines 2409 Bytes #999 (0) @ WW
BID : 1924_PA2WIV
Read: GUEST DB0FHN OE7FMI
Subj: Re:Coax Balun
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<PI8WFL<PI8HWB<PI8DAZ<PI8PWD
Sent: 040223/1200Z @:PI8PWD.#DRE.NLD.EU #:3393 [Schoonebeek] $:1924_PA2WIV
From: PA2WIV@PI8PWD.#DRE.NLD.EU
To : TECHNI@WW
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>From: G8MNY@GB7CIP.#32.GBR.EU
>To : TECH@WW
>
>By G8MNY (new Graphics 12/03)
>This type of balun is to be found in most textbooks & many aerial designs.
>
>Balun is ¬ wave of scrap coax alongside the feeder (a pipe will do).
>
> ÚÄÄÄÄÄÄÄÄÄÄÄÄ¿
> BÄÂÄ@ dead coax ³ @=Solder
> ³ ÚÍÍÍÍÍÍÍÍÍÍÍÍÏ@ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
> ÀÄ) FEEDER
> BÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
>
>The feeder inner is connected to the dead coax braid BB are the 50ê balanced
>feed points. The dead coax is what it says, a shorted out at both ends bit that
>could even be copper pipe of the same diameter. It is connected to the feeder
>¬ wave back from the aerial where the braids join together. At the aerial end
>the dead coax is connected to the feeder's inner.
>
>This works by making the aerial connections look "balanced", as the ñ voltage
>phases appear to radiate equally from both halved of the balanced ¬ wave lines
>& hence cancel, the 2 balanced folded ¬ waves look like a « wave where the
>centre is at RF ground & therefore can be connected to the feed coax outer
>without any RF left on the outer of the coax skin.
>
>/QSL
>73 De John, G8MNY @ GB7CIP
....speaking of 'a pipe': This pipe can be placed over the feeding coax,
and then it is called 'Powsy stub' ...or is it 'Pawsy stub'? You will find
it in the 'VHF UHF MANUAL'. Of course the pipe must be solderable, a copper
pipe (used for water/gas) will do.
Vy 73 Tinus PA2WIV@PI8PWD
e-mail alias at: amsat.org / qsl.net
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