[TowerTalk] Foam cables and velocity factor

Robert Chudek k0rc at pclink.com
Fri Nov 11 17:25:54 EST 2005


The cable wasn't rated per se. It is a foam dielectric so I guestimated .8 
as a starting point. Can the true VF be determined from the data I

73 de Bob - K0RC

----- Original Message ----- 
> From: "Tom Rauch" <w8ji at contesting.com>
> To: "Robert Chudek" <k0rc at pclink.com>; <towertalk at contesting.com>
> Sent: Friday, November 11, 2005 1:41 PM
> Subject: Foam cables and velocity factor
>> From the L=(246/F)*2 formula I calculated 215 feet would
>> be needed using coax with a velocity factor of 80 percent. I
>> whacked off a 222 foot chunk, installed a PL-259 on one end,
>> and started my "education".
> Solid dielectric cables have a very consistent velocity factor of .66
> Foam cables can be anywhere from .66 to .9 or so.
> So did you just pick .8, or was it in the cable specs for that cable??
> 73 Tom

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