> > 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.
... Joe, W4TV
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