[TowerTalk] Measuring Coax Length

[Roger (K8RI) on TT]

Likewise!

  I used to believe that if you properly weatherproofed the connections 
on 9913, all would be OK.  Then the tower took a direct lightening 
strike that removed all the weatherproofing and plating from the 
connectors.
A few minutes later I had water running out of the 2-meter rig and onto 
the desk.  It also ruined the desk.

I gave away all the 9913 I thought I had, which was about 1500 feet, 
plus a few hundred feet of unused.  A couple years ago, the SWR went up 
on the 40 meter center fed, half wave  sloper.  When I disconnected a 
splice in the junction box where the cable came in, water ran out, so I 
had missed a piece.

I replaced all  of the free swinging coax to the slopers with Davis 
BuryFlex (TM)  Although I have used 8X successfully to the 40 antennas 
running the legal limit with no failures.  I prefer the 8X in that use 
as it has low wind resistance.

73

Roger (K8RI)

On 10/28/2014 9:31 PM, john at kk9a.com wrote:
> 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 at contesting.com>
> Subject:	[TowerTalk] Measuring Coax Length
> From:	Mike Fahmie via TowerTalk <towertalk at contesting.com>
> Reply-to:	Mike Fahmie <wa6zty at 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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-- 

73

Roger (K8RI)