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Re: [TowerTalk] Coax

Subject: Re: [TowerTalk] Coax
From: K8RI <>
Date: Mon, 09 Apr 2012 12:16:43 -0400
List-post: <">>
On 4/9/2012 1:59 AM, Jim Brown wrote:
> On 4/8/2012 9:12 PM, K8RI wrote:
>> I don't know if the big coax makes much difference on 75 but the
>> resistive loss is much less on 160 compared to the RG-8 size cables.
> I'm certainly not advocating against coax that is truly lower loss --
> the runs to all of my Al antennas are either hard line or heliax, and
> I'm using low loss RG11 to feed high wire dipoles for 80 and 40.
> Rather, I'm simply observing that Davis's 213 is half the cost of
> LMR400,

It is more economical, but not that much. On a per foot basis, Davis 213 
is 78 cents while I can find LMR-400 at 89 cents, or about 14% more.  Of 
course in 500 and 1000 foot spools they are both, notably less

>   with essentially equivalent performance on the HF bands.  If I'm
> paying twice as much for coax, I want to get my money's worth. :)
> As to the life of coax -- I don't have your decades of experience with
> LMR400, but I did have occasion to re-cycle hundreds of feet of 20 year
> old RG8-size coax of various pedigree from the estate of a silent key.

I had well over 1000 feet of LMR-400 that I replaced with LMR-600. Most 
was in 100 and 200 foot lengths.  It was only about 10 years old, but 
sold most of it for about 20 or 30 cents per foot. I did give a bunch to 
friends who had helped me with the towers and station set up and I have 
standing orders from the locals if I pull out any more.  . Most of the 
Belden went out to the road.  They had a choice and no one wanted the 
Belden when they could have the LMR-400.

No one wanted the LMR-400UF either.  All they had to do was cut open a 
section to find water damage and it didn't get in at the connectors 
either.  We cut open one piece and found about 5 or 6 feet mostly white 
powder in the middle.  I figured I'd take the best pieces and make 
jumpers.  I had made two or three jumpers from a 28' piece  when I hit 
another section where the shield had turned to white powder.  The jacket 
looked fine except for being a dull color.  I could find no holes in it, 
but evidently it was porous, or had pinholes in it. I have one piece 
that has the braid showing where the rotator loop wore through, jut 
laying on the 45G top plate.  I think I kept that piece to show people 
why I don't like the UF versions.   I threw the rest away and figured 
that was a good job for what little new LMR-400 UF I had left.  
Unfortunately I think I have at least two, 200 foot coils of LMR-600 UF, 
but I can use that in the conduit where it's protected.

> Most of it was Times or Belden, and most of it had been outside for most
> of those decades. I couldn't give it away, so I made stubs out of it and
> measured their response. The attenuation of a stub is directly related
> to its conductance at the frequency of the null, and virtually all of
> that old cable that hadn't gotten wet inside measured as good as new. He
> also had some low grade stuff, and I threw that away.  I also bought all
> of his heliax and a huge spool of 1/2-in CATV hard line.

I had a bunch of 1/2" and 3/4" CATV hard line as well.  I gave away a 
lot of the 3/4" and used a couple of runs to the top off the tower for 
144 and 440.
No one wanted the 1/2". I've never had good luck with either the 1/2" 
CATV cable or 1/2" Heliax.  They have always ended up getting kinked.


Roger (K8RI)

> 73, Jim K9YC
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