[TowerTalk] RMC 1000 Remote cable
Joe Subich, W4TV
k4ik at subich.com
Thu Nov 3 19:04:39 EST 2005
If one wanted to avoid the rotary joints and "hose reels" it is
possible to copy from what the broadcasters have been doing on
TV news (microwave) vans for 30 years. They use a "nycoil" which
is simply a long, flexible conduit wrapped around the mast.
The microwave masts generally extend 40' or so above the roof
of the van ... the nycoil is about twice the length of the
extending distance (75 to 100' for a 40' extension).
When the mast is retracted, the nycoil coils around the base of
the mast (on the roof of the truck) in a basket about five feet
in diameter and two to three feet deep. when the mast is
extended, the coil spirals downward from an attachment point
at the top. Some truck builders add supports part way along
the mast (generally a chain or piece of aircraft cable) to
help reduce the stress at the top of the conduit.
The one problem with "nycoil" for amateur use is that it is
limited to 1.25" diameter. However, I suspect the same thing
could be done with non-metallic conduit (Sealtite) which is
available up to two inches inside diameter.
... Joe Subich, W4TV
microHAM America, LLC.
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