[TowerTalk] Rotator Loop Suggestions

[Doug Turnbull]

If you are concerned about abrasion look for a product called Spiral Wrap
which is normally used to tidy up cabling.   Spiral wrap is perhaps a
sixteenth of an inch thick plastic which can be wrapped around the service
loop and further secured with some electrical tape.   On my tower I have a
couple of places where the service loop naturally rubs so I used a second
layer of spiral wrap.   This seems to do the job nicely for me.

Because I have two small stays from the very top of the tower to an
anti-torque arm just below the tower head, I have enclosed these meter long
stays along with their turnbuckles in rectangular plastic trunking used for
electrical wiring.   This trunking snaps together but I have added
additional electrical tape to keep it together.   Thus I try to ensure the
service loop of RG231 rubs against a smooth surface.   The service loop
itself is quite loose and perhaps a bit longer than needed but it moves with
ease.

                 73 Doug EI2CN

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Robert Harmon
Sent: 30 March 2011 01:13
To: K8RI on TT
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] Rotator Loop Suggestions

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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