K7LXC@aol.com K7LXC@aol.com
Fri, 14 May 1999 05:21:36 EDT

In a message dated 99-05-12 14:39:07 EDT, froemke@ibm.net writes:

<< Any advice on the problem of routing cables above the top of a Rohn
 25AG4 top section when the first antenna boom (of the stack) is within
 12 inches above the flat top tower section? As the mast rotates (450
 degrees with a Yaesu rotor) the cables tend to rub on the top guys with
 very little space in the gap between the top guys and lowest antenna
 boom. The Rohn 25AG4 flat top has "tabs" on all three corners for
 connecting to guys that guarantee that the cables will at least rub on
 and may also get hung up as the mast rotates through the full 450 degree
 >>I'm planning to use one LMR-400 UF, one Heliax FSJ4-50B Superflex (or
 LMR-600 UF) and several control cables between the tower and mast. (The
 actual rotor is well down in the tower.)
         Most people use a big rotation loop between the mast and tower. If 
you start the loop a foot or two from the mast on the bottom boom, that might 
give you enough clearance.

      The other thing you can do is to loop the feedlines around the mast at 
the top of the tower 2-3 times. Then the coaxes are only moving a little for 
each revolution. You'll have a pile of cables laying on the flat-top but 
they're not going anywhere. And no getting caught on tower hardware.

     Is the LMR cable suitable/flexible enough for this kind of duty? 

>> Would Phillystran guys be damaged by the rubbing and pulling of these
 cables across the top guys?  >>
      Yes. The Phillystran PVC jacket doesn't take abrasion very well. You 
can always tape thoroughly over the Phillystran to give it some help. The 
tape would be sacrifical. 

Cheers,   Steve   K7LXC

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