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Re: Topband: Coax velocity factor

To: <topband@contesting.com>, "Charles Bibb" <zedkay@bellsouth.net>
Subject: Re: Topband: Coax velocity factor
From: "EP Swynar" <gswynar@durham.net>
Date: Wed, 28 Mar 2007 06:43:43 -0500
List-post: <mailto:topband@contesting.com>
On 27th March Charles wrote...

> Every time I get the same results: VF=84%.  This just seems a tad high to
me, especially when 75% is the published value for RG-6, though I know the
VF of foam cable is higher. Anyone else get similar results when checking
this type of cable?

**************************

Hi Charles,

I don't have access to my notes here at the present moment to confirm
specifically, but I do recall that your 84% VF figure is VERY close (if not,
indeed, the same) to the VF of some RG-6 coax that I employed here last
autumn in my phased "L" transmitting array...

I employed the ON4UN method (described in his book) in calculating the VF of
mine, i.e., I hooked-up an SWR meter between the rig & a "T" connector --- a
52-ohm dummy load was attached to one end of the "T", & a "calculated"
length of 135-degree SHORTED RG-6 was attached at the other end.

The rest was merely an exercise in some basic mathematics, dependent ipon
the 1:1 SWR point/frequency of same...

~73~ Eddy VE3CUI - VE3XZ

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