Many cable manufacturer, especially manufacturers of better quality of cables,
put a "serial number" (sort of) along the cable. You can recognize it as a
running number along the cable. These numbers are one foot apart. Look for it
at each end of the cable subtract the lower number from the higher number and
you have the length right there.
It's used to keep track on cable inventory.
73 de,
Hans - N2JFS
-----Original Message-----
From: john <john@kk9a.com>
To: towertalk <towertalk@contesting.com>
Sent: Tue, Oct 28, 2014 9:32 pm
Subject: Re: [TowerTalk] Measuring Coax Length
I would not use Belden 9913 outdoors, especially if underground. Some
years back I also purchase 9913 but I threw mine away because it was too
susceptible to water ingress.
John KK9A
To: Towertalk Reflector <towertalk@contesting.com>
Subject: [TowerTalk] Measuring Coax Length
From: Mike Fahmie via TowerTalk <towertalk@contesting.com>
Reply-to: Mike Fahmie <wa6zty@yahoo.com>
Date: Tue, 28 Oct 2014 21:15:55 +0000 (UTC)
Some years back, I purchased a 500' reel of Belden 9913 and used a bit
here and
there over the years. Now I needed four 70' runs to the base of my tower but
didn't know how much 9913 remained on the reel.
My DVM can measure capacitance so I connected it to the free end of the reel
and measured 6300 pF. Belden says that 9913 capacitance is 24.6 pF/ft so
dividing that into 6300 pF implied that I had 256 ft remaining. That was
enough for three 70' runs but not enough for four, oh well.
I cut three 70' lengths from the reel, 45' of cable remained. (3 x 70) +
45 =
255. That is just 1 ft less than what was predicted by the capacitance
measurement !!! Isn't it nice when the numbers work out so well. Will I
rely
on that technique in the future? Nope, gotta see it work out like that a few
more times first!
-Mike-WA6ZTY
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