[TowerTalk] Rotator Loop Suggestions

[K8RI on TT]

On 3/29/2011 4:33 PM, Paul Saville wrote:
> I have tried various configurations for a rotator coax loop, ranging
> from a 10ft length of coax hanging in a single loop from the boom, to
> rg58 wound fairly tight around the mast. It seems the optimum would be
> to drop the coax as close in to the mast as possible to reduce the
> turning radius, but far enough out to avoid snagging. Does anyone have
> any hints or clever suggestions?

I use a 3 turn coil of Davis BuryFlex(TM) about 16" to 18" in diameter 
to get a "large" turning radius laying on the flat top of the 45G  . The 
large diameter puts less bending moment on the coax.  The coax needs a 
flat surface on which it can skid. Even a second rotatorshelf/acessory 
shelf anywhere between the rotator and top of the tower will work for 
the shelf supporting the loop. with the outside end of the loop going 
down one of the tower legs.

With the 18" diameter I can actually get by using regular LMR-400. I've 
not tried it with LMR-600, but I assume it'd work.

The coil expands and contracts with rotation rather than bending in the 
normal manner so it takes a bit if calculating, or experimentation to 
get the right length to keep the coil on the flat plate.

If using any of the UF versions such as LMR400 or 600UF the flat plate 
needs to be *smooth* and I have to emphasize the smooth, as the jacket 
of the UF cables is not only sensitive to UV it is easily abraded.  This 
is where the BuryFlex shines as it has a very tough jacket that is 
strongly resistant to abrasion, plus it has about the same loss as LMR-400.

73

Roger (K8RI)

> 73 Paul ZL3IN
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