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[TowerTalk] Freqent crank-up tower recmmendation

To: <>
Subject: [TowerTalk] Freqent crank-up tower recmmendation
From: "Jim Thomson" <>
Reply-to: "Tower and HF antenna construction topics." <>
Date: Sun, 28 Feb 2010 15:29:21 -0800
List-post: <">>
Date: Sun, 28 Feb 2010 02:57:39 -0500
From: "Roger (K8RI)" <>
Subject: Re: [TowerTalk] Frequent crankup coax recommendation wrote:
> LMR400 is a solid center conductor cable, A poor choice for cranking up and 
>  down.
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 
10m alone! 

Later... Jim   VE7RF


Roger (K8RI)

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