[TowerTalk] Coax recommendation

[alsopb]

Jamie,

I don't understand this at all.  I have two crank down towers
(actually towers with Hazers) and had an EZ-way telescoping/tilt over
tower.

The trick is to not attach the coax directly to the tower except at
the very top.  If you are concerned that the weight may be as issue,
you can run a KEVLAR or phyllistran "messenger line" from the top of
the tower and attach the coax to that. The 1200 pound stuff is cheap,
indestructible and easy to tiewrap/tape the coax to. The messenger is
likewise secured at a fixed point at the bottom of the tower.  When
you crank down the tower, the coax just pays itself on the ground.  No
binding and the coils just form almost automatically.  

I have LMR-600 to one tower (350') and LMR-400 (150') on the other. I
calculated the loss of LMR400 in the 150' run to be about 1db on ten
meters which was acceptable to me.  I transition to RG213 for the 6 to
10' of rotor loop. The extra loss on the HF bands is negligible.  I
also have some LMR-400 superflex. It probably would do for the rotor
loop as well but at more cost.

73 de Brian/K3KO

"James C. Hall, M.D." wrote:
> 
> Gentlemen:
> 
> I am trying to decide on a proper cable arrangement for my 72' crank-up
> tower which is 125' (approx.) from the shack that will have Force 12 Mag
> 620/340 and 4BA on the mast with 10' separation.  My thought is to use
> LMR-600 from the SPG to the tower junction box and much more flexible stuff
> to the coax switch, from the switch to the tower leg grounding point, and
> from the SPG to the shack.  My question pertains primarily to the run up the
> tower to the antennas (4 of them).  It has been suggested to use LMR-600
> with its low-loss properties up the tower to a point (at the tower top
> grounding point) and then use flexible stuff (9913 or LMR-400UF).  My
> problem is that it's a crank-up tower that has the potential to crack the
> solid center conductor when it is cranked down.  Am I being overly cautious
> here or is this valid ?  Concrete will be poured this Thursday !! (Yes, I AM
> excited ).
> 
> I plan on placing a small junction box at the tower where there will be
> received 120 VAC as well as a place for strain relief and weather protection
> of the connectors.  Now , I'm kinda new at this.  Please explain why this is
> necessary.  Originally I had planned to blow all these cables down the PVC
> to the SPG where the lightning protection gear would receive them and then
> on to the shack.  Am I missing something here ?
> 
> Jamie
> WB4YDL
> 
> List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
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> 
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List Sponsored by AN Wireless:  AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!!  http://www.anwireless.com

-----
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