I recently rewired a TV van 45' air operated mast. These use a Nycoil
coiled nylon hose to hold the many control and coax cables to the mast
head (15 cables were in the 1.5" ID Nycoil replaced). Nycoil is
incredibly tough, and has a built in coil memory (which makes it very
tough to pull cables through the length needed for a 45' mast!) and
expensive.
However, an alternative might be to use a short length of black PVC
well/water pipe/hose over the assorted coax cables to keep them coiled
for a turn or two or three and protect them from abrasion. Some sort of
clamp would be needed at the tower and mast ends to hold the hose. This
stuff is cheap and available in several diameters at HD/Lowes/etc.
Anybody done this?
Grant KZ1W
On 3/29/2011 5:12 PM, Robert Harmon wrote:
> Roger,
> I have some LMR 600 ultra flex that I will need to do a turning loop
> arrangemet with.
> I am wondering if it is possible to do a 3 or 4 turn coil that is in a spiral
> configuration
> around the mast, then there would be little abrasion Just thinking.........
>
> Bob
> K6UJ
>
>
> On Mar 29, 2011, at 3:41 PM, K8RI on TT wrote:
>
>> 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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