Date: Sun, 28 Feb 2010 02:57:39 -0500
From: "Roger (K8RI)" <K8RI-on-TowerTalk@tm.net>
Subject: Re: [TowerTalk] Frequent crankup coax recommendation
> LMR400 is a solid center conductor cable, A poor choice for cranking up and
Depends... If you are talking about a mast with the coax spiraled around
it like a coiled spring it'll work just fine.
## It still won't work... on a crank up. Nobody is about to spiral rigid coax
the tower itself... much less the mast on top. Why not just use the correct
to start with.. like LMR-400/600 Ultra Flex.... or the Davis Bury flex. The
Bury Flex sounds like the ticket. Then the fellow could bury the coax from
to base of crank up.. and continue on up the side of the crank up.
## No point in using rigid coax, like LMR-400DB [solid center conductor] going
up the side of a crank up. IT WON'T FLEX.
## I'm installing a HDX-689 in 2 x months.. and have the same issues. My
proposed 'fix' is to run LMR-1200DB, from shack to base of crank up,
and either continue up the 1st 20' of the bottom section of the new
crank up, or up the 1st 20' of the old tower... [ old tower is immedediately
adjacent.. and it's all coming down, except the bottom 2-3 sections, Trylon].
## LMR-1200DB, then is spliced into either Tcom -600UF , or RG-393,
both are flexible. One flexible cable up the side of the crank up, to
AS remote switch box, mounted on mast. Then 3-4 x separate runs
of coax to each ant. By installing the remote switch box on the mast,
there is only ONE rotor loop involved, not several rotor loops.
## all coax braids get grnded at top of tower.
Would I use it that way? Probably not, but I would use it for a rotator
loop if the need arose and I know it works quite well if installed
properly. OTOH, As I ground the coax at the top and bottom of the tower
which means I am going to need a connector in the cable at that point
anyway, I might just as well install a rotator loop using Davis
BuryFlex (TM) or another good, flexible cable. Three of the 4 loops are
28' while the one to the tri-bander is only about 18'. With 4 cables
bundled together I need all the flexibility I can get.
## are u using all these ant's simultaneously?? IF not, why not use
a remote switch box on the mast... and run ONE coax up the tower,instead
of several of them?? For a fixed tower, I'd take ONE run of LMR-1200DB/
7/8" heliax up the side of a tower any day... VS 2-6 x runs of 213-U....esp
if you are talking about a long run of coax. There is a huge diff between
LMR-1200/ 7/8" heliax VS 213. 213-U has FIVE times the loss on
Later... Jim VE7RF
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