[TowerTalk] Coax and cable loop at antenna

[K8RI]

On 9/9/2012 8:18 PM, Jim Lux wrote:
> On 9/9/12 5:08 PM, Rick Kiessig wrote:
>> How do you figure out how much coax and control cable to put between your
>> rotator and the antenna?

The short answer is enough to reach, plus the rotator loop.

>>
>> How do you secure those cables on both the tower side and at the antenna?

On regular towers I just use tape to form a band 2 to 3 inches wide

>>
>> What kind of coax do you use there? BuryFlex or something else?

It depends on what you use for your regular coax.  If it's a flexible 
RG-8 I just use more of the same. That way I don't need to add more 
connectors. I also use tape to hold the coax under the boom from the 
tower to the feed point.

I do not like cable ties used on coax.  They are narrow and can exert a 
lot of pressure on the cable which may distort said cable.


>>
>> I'm also looking for a good way to secure cables to the outside of the
>> tower. I'm not using a Rohn-style with multiple smaller support posts.
>> Instead, it's a single pole, 220mm in diameter. I'm reluctant to just use
>> long plastic cable ties. Is there a better approach?

That's roughly 8 1/2 inches


>
> They make "stick on" things that look like the saddles you use with zip
> ties to hold cables on a chassis, but made of metal or UV resistant
> plastic with a bit of curvature.
>
> To attach those, they have double stick foam (3M VHB - Very High Bond, I
> think) that is very weather resistant (used for holding windows in on
> skyscrapers, for instance).  I have a 15-20 year old roll of VHB and
> lots of things stuck up outside for more than 5 years that are still
> stuck (in Southern California, so we don't get freezing very often, but
> it does get hot.. surface temp in the sun is probably well over 60C)

I've seen metal surfaces way up here in Michigan reach over 100C laying 
out in the sun.  I believe a flat,  protected surface of the proper 
color can reach well above 300F

>
> There are things which can be epoxied on, as well.  Epoxy will never
> come off, if the surface is properly prepared.
>

Typical epoxies that most of us use or that you find in the hardware 
section will soften and fail in some areas.  There is a reason that most 
small composite aircraft are white. Park one that is green, black, or 
red out in the sun and you will be able to see the rib and stringer 
outlines through the skin in a few hours.
Check the temperature range for any specific epoxy. I use Vinylester 
Resin which has a notably higher softening point and much lower 
viscosity allowing for a much denser weave in the fiberglass cloth. 
Unfortunately it has a relatively short shelf life once promoted 
(Factory says 3 months, but typically less than a year. Much less if not 
kept cool).  Cure time is only about 15  to 20 minutes depending on how 
much catalyst you use, how much promoter was originally used and the 
working temp.  Working and cure times are highly variable. Plus the 
stuff is expensive at over $80 a gallon and requires hazmat shipping as 
the catalyst is Methyl Ethyl Keytone Peroxide

On a pole I'd be tempted to fasten on the same kind of cable hangers 
they use on crank up towers.  Can't remember the name of them though.

73 and good luck

Roger (K8RI)


>
>>
>> 73, Rick ZL2HAM
>>
>>
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