[TowerTalk] Reusing Coax

Fri Dec 10 15:00:54 PST 2010

Roger,
Some comments based on my own experience.

When I lived in Eastern Ohio from 1978-79, I had one piece of old  
RG-213 that I used between my tuner and the 40m vertical that I used  
on all bands.  When I removed it after only one year of use, it had a  
considerable amount of moisture within the coax that I attributed to a  
poor job of 'taping' the connector at the antenna.  I threw the major  
portion of that 50' piece away, but made some jumpers of the remainder.

Moving to Indiana in 1979, I purchased 500' of RG-8X and buried a line  
of about 150' length from the house to the 40m vertical array in the  
North pasture.

When I moved to Michigan in 2004, I removed that buried coax (pulled  
it up with a garden tractor ... and found it in what appeared to be  
NEW condition, despite being under the topsoil for 25 years!

I tested it with the appropriate power meter and dummy load and was  
astounded to find that, after removing about 10' at each end, the  
remainder tested like NEW!  Talk about a surprise!

Now that I'm up here in Michigan, I haven't used any RG-8X YET, but  
have a 531 METER roll that I bought in Dayton, Ohio, a few years ago,  
from which I am now making jumpers.

My present vertical antenna arrays are fed with military surplus  
RG-213 with N-connectors and N-to-UHF adaptors ... work quite well and  
will make the installation permanent and buried next Spring.

Had one incident with the RG-213 here in Michigan ..seems the  
chipmunks LOVE it .. and have some 'nicks' in the jacket due to their  
'nibbling' .. taped over those 'nicks' and all works fine.

I will continue to use RG-8X up/down towers to yagis and diples as  
working with it is very easy.

73
Don
N8DE

Quoting "Roger (K8RI)" <K8RI-on-TowerTalk at tm.net>:

> I've had some SWR problems when using the DL5K above 20 meters and
> decided to try replacing all the 8X in the system with LMR-400UF.  I did
> have LMR-400 between the amp and AT5K.
>
> As some may remember I had problems with LMR400UF  pigtails with some of
> it splitting, but I had a fair amount that appeared good. Each pigtail
> was 28' long so if any could be reused it was certainly worth saving. As
> most of the connectors were N type I had to remove them or use adapters,
> but wanting to use UHF connectors and also wanting to check the interior
> of the coax including shield, I decided to remove the connectors. All
> connectors were clean and the braid shiny so figured the rest in between
> had to be good so I proceeded to install UHF connectors and cut the
> cables to the appropriate lengths. I was into the third cable when on
> removing the jacket I discovered the braid was dull and contained a lot
> of white powder.  Even carefully inspecting the jacket I could find no
> splits or worn spots and this was essentially in the middle of a 28'
> piece. All the remaining "used" 400UF is now on the junk pile (a few
> with shiny connectors)  and I started over with some new 400 UF I had on
> hand.
>
> I figure on saving the Davis BuryFlex(TM) for the new pigtails while
> using up the 400 and 600 UF either indoors or in conduit where it is
> protected from the elements.
>
> Going back to my tower project and the chronology I figure the 400UF was
> installed in 2001 and 2002. It was removed around 2006, so it was only
> up there about 5 years. Not nearly as long as I had thought.
>
> A couple years ago I discovered a piece of 9913 left over from when gave
> away and threw out about 1500 feet of the stuff .  I used it to feed one
> of the 40 meter sloping dipoles. One day the SWR started jumping around
> and the Alpha 76 was showing intermittent high reflected power.  My past
> experience with 9913 was hollering "WATER" loudly.  There was a splice
> in the cable just inside the 2" EMT inside the shop. I had to pull it
> back about 2 to 3 feet to get at the splice.  Even though it was indoors
> it was still tapped up.  When I peeled the tape off there were water
> droplets on the outside of the connectors.  When I disconnected the 9913
> from the LMR400 a stream of water ran out onto the floor. So, I pulled
> the cable back out through the junction box. let the antenna down, and
> removed the coax.  About 15 feet from the antenna end I discovered a
> hole that went through the jacket, braid, and into the dielectric. That
> let water run down the high side of the antenna  and 15 foot of coax
> before it could get inside the run down into the shop.
>
> What put the hole in the coax? It might possibly have blown against the
> edge of the shop roof, but in retrospect that would have taken a pretty
> strong wind. Critters?  Bout the only thing that would be up there (at
> that angle) would be one of the large woodpeckers we have around here,
> but I can't imagine one hunting for bugs in the coax. OTOH they have
> tried to get bugs out of the vinyl siding and when they do that it's
> like being on the inside of a drum.
>
> In one case the coax was bad. In the other the coax was a poor choice. I
> probably would have had the same problem with new 9913.  Just one more
> reason  why I no longer use 9913.
>
> 73
>
> Roger (K8RI)
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