[TowerTalk] Rotator loops

[Joe Subich, W4TV]

> > I have also noticed that TV station remote trucks 
> > seem to use another solution for their rotating dishes - 
> > they wrap a few turns of coax loosely around the mast, so 
> > that a one-turn rotation only slightly loosens or tightens 
> > the wrap.  Seems like this would be a better, more 
> > durable practice for ham installations too.
> > 
> I agree.. they also do this to accommodate the big difference 
> in height as the mast extends, so the coax neatly stacks as it 
> comes down.

Having designed and built those trucks for a few years, there 
are two issues here: 

1) mast height is accommodated by the many turns of the "nycoil" 
   which stretches like a slinky as the mast is raised.  By the 
   way, the length of feedline is almost double the mast height. 

2) the antenna rotation is accommodated by a single loop.  The 
   "nycoil" is attached at the top of the mast for support.  The 
    mast does not rotate - only the antenna rotates. 

73, 

   ... Joe, W4TV