Hi !
On Wed, 17 Jul 2002, Larry Bush wrote:
> Building a couple of 8 element 430 MHz Yagi on 1 inch PVC boom.
>
> The driven element is a dipole with direct feed of 50 ohms. From the driven
> element I have 3 foot of RG-58A terminated into a type N female connector.
>
>
>
> I thought a common-mode balun wound with the RG-58 around the 1 inch OD PVC
> boom would be neat so I computed the reactance needed at .4 micro-Henry,
> which is five turns on the boom. During my research I was could not find the
> use of common-mode baluns on frequencies higher than 6 meters. I have three
> questions:
>
>
>
> 1 Will a common-mode choke work on 430 MHz?
>
NO !
>
> 2 Will the capacity coupling between turns of the balun at 430 MHz make the
> choke ineffective and if so would winding the balun by spacing the turns the
> diameters of the RG-58 help?
>
YES !
>
> 3 How would one check the common-mode currents on the yagi models?
>
Check the SM5BSZand G3SEK sites, there is answer to all questions.
>
>
>
> Larry Bush, W5NCD
>
>
>
P.S. Yes I know about ferrite beads - it. FAR the BEST solution.
73 !
Jiri
OK1RI
P.S.1 I know also something about VHF antennas - check www.qsl.net/ok1kim
not yet upgraded but now 27 booms together long 187m.
P.S.2 Why for the God's sake you use PVC boom ? Use normall Aluminium
boom, the elements insulated above the boom and you are fine, than you can
only tape the coax to the boom and you are set ! - see G3SEK site
with measurements from the real word.
>
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