[TowerTalk] Bundling of tower coax and control lines

Sun Nov 17 05:23:45 EST 2013

On 11/16/2013 2:04 PM, Jim Miller wrote:
> Light scatters as a function of wavelength and particle size to interact
> with. You see the results of scattering when you look on the horizon and on
> one day see a white haze which is scattering off water and other large
> molecules for all visible wavelengths (hence white) and on other days it
> may be blue to the horizon where that wavelength is scattering strongly off
> oxygen molecules strongly vs longer wavelengths.

Take some photos of the horizon from a ridge line or from a few
thousand feet from an older small airplane using B & W film.
The windshield and windows in older planes were not UV protective
and B & W film is sensitive to UV light. Take photos with color
film as well. Compare the results. Quite often you can not see,
or barely make out the horizon in the B & W photos and it will
only be a bit hazy in the color shots. That haze in the B&W shots
is from the UV light.  .

Pilots flying  those old airplanes at 10,000 feet could get some
really bad sunburns wearing a short sleeve shirt,  Course some
would take their shirts off to get a fast tan, but usually got burnt.
Those planes might have had a 1/8th inch windows although I think
some were only 1/16th.

Mine had a 1/2 inch windshield with 1/4" side windows that were
UV protected and tinted.  It gets pretty bright up there above the clouds..
Exposure increases about 10 to 12% per 1000 feet.
BTW, reflections from new snow can double the UV exposure. I don't know
about sand, Google is your friend,

73

Roger (K8RI)

>
> UV continues this strong scattering behavior with oxygen molecules.
> Anything that gets past the ozone layer will repeatedly scatter with little
> absorption resulting in it coming at you form all angles regardless of
> attempts to screen the direct sunlight. The first order criteria for
> resulting exposure is the amount of horizon you can see whether "in the
> shade or not."
>
> Jim ab3cv
>
>
> On Sat, Nov 16, 2013 at 11:34 AM, Patrick Greenlee <patrick_g at windstream.net
>> wrote:
>> Larry, It is basically an intensity and exposure time issue. I sunburn
>> easily. I can attest to getting a sunburned forehead while wearing a big
>> brimmed hat while fishing. The reflected UV can be quite powerful.  Often
>> reflected intensities are less than direct by quite a margin but can still
>> be sufficient to accelerate deterioration. It is a matter of the nature of
>> the reflecting surface and its orientation that determines the percent of
>> light that is reflected. Chemical change (what we call deterioration) is
>> accelerated by elevated temperatures.  Heat and light are both factors in
>> deterioration  and don't forget smog or reactive atmospheric components
>> like ozone etc. In general the higher the temperature the faster the
>> chemical reaction.  Similarly the brighter the light the faster the
>> deteriorating effect.
>>
>> Light when absorbed heats the object but that isn't why UV is a
>> significant player in deterioration. The energy in a quanta of light is
>> dependent on the wavelength (color.) E = h nu (I spell the Greek lower case
>> letter nu as it isn't on my keyboard and I don't know how to get it or if
>> it is available in the extended character set supported by Windows.) OK, in
>> the above formula E is energy, h is Plank's constant, and nu is the
>> frequency.  It is easily seen that the higher the frequency the more
>> energetic the photon.  From red to blue is an increase in frequency. Ultra
>> Violet is bluer than blue, higher in frequency and more energetic.  The UV
>> knocks the electrons of some atoms into higher orbits than they usually
>> achieve this stores more energy than normal and releases this energy when
>> they return to their ground or original state.  This energy is what makes
>> for energetic photochemistry.  Think of it as UV supplying the energy of
>> self destruction as well as catalysis of oxidation.
>>
>> Light is quantized in photons.  Each UV photon has a probability of
>> causing damage to a susceptible material Bunches of UV causes bunches more
>> damage. There is not a lower intensity threshold below which UV does no
>> damage. Less UV does less damage but each photon has the sane damage
>> causing potential so it is a pure numbers game where less is better for
>> survival of susceptible materials.
>>
>> Executive summary:  Light usually good, UV often bad.
>>
>> 73
>>
>> Patrick AF5CK
>>
>> -----Original Message----- From: Larry Loen
>> Sent: Saturday, November 16, 2013 9:41 AM
>> To: Patrick Greenlee
>> Cc: TowerTalk
>> Subject: Re: [TowerTalk] Bundling of tower coax and control lines
>>
>> Good thoughts from one who has been there.
>>
>> Question for you:  Is direct sunlight more important than the reflected
>> kind?  I seem to remember that you can get sunburned from reflections off
>> of sand just as direct sun.  But, I also know that UV tends to be absorbed.
>>
>> I'm wondering if it helps at all to simply get stuff out of the direct
>> sun.  I suppose there will still be some UV from reflections off of the
>> sand, but I also wonder how much the intensity goes down when you expose
>> yourself only to that.  Longer is longer however it is achieved.
>>
>> Do you know?
>>
>>
>> WO7R
>>
>>
>>
>> On Sat, Nov 16, 2013 at 7:40 AM, Patrick Greenlee
>> <patrick_g at windstream.net>wrote:
>>
>>   Larry, the canvas is a good idea and it can be painted as well to extend
>>> its life.  Good UV resistant house paint will do the job.  I have seen old
>>> used canvas hose used to protect cables. I remember the problems I had a
>>> few decades back with my mom's south facing wooden entry door at Bull Head
>>> City Arizona.  I never found a coating (paint) that lasted more than a
>>> couple years at best.  The intense sunlight with strong UV components and
>>> elevated temps can be difficult to deal with.  I'm currently looking for a
>>> thin flexible tubing (round or flat on a roll) that is UV resistant and
>>> flexible when cold. Simple criteria but difficult to satisfy on a moderate
>>> budget.
>>>
>>> 73 and best of luck to you.
>>>
>>> Patrick AF5CK
>>>
>>>
>>> -----Original Message----- From: Larry Loen
>>> Sent: Saturday, November 16, 2013 8:05 AM
>>> To: Patrick Greenlee
>>> Cc: TowerTalk
>>>
>>> Subject: Re: [TowerTalk] Bundling of tower coax and control lines
>>>
>>> I live in the low Sonoran dessert (1400 feet above sea level) and UV is
>>> something we worry about around here.
>>>
>>> My stuff is too new at about a year in place, but I am wondering a bit
>>> about some of my setup.  I have an MOV box that is discolored (no other
>>> problems; no cracks, etc.) and I have some exposed PVC conduit that is so
>>> far unchanged, except for one slightly darker elbow.
>>>
>>> The Home Depot actually suggested that ordinary paint could prove to work
>>> well for cables.  I haven't tried that one yet.  Maybe it buys an extra
>>> year or two before the paint cracks?
>>>
>>> I am also wrapping some of my ground level cable in canvas.  I figure that
>>> it is thick enough to block it.  If the canvas dies, it would be cheap
>>> enough to replace.
>>>
>>> I haven't though about what to do about the cables hanging from the tower.
>>> I was kind of resigned to replacing them eventually.  My tower is a
>>> crankup
>>> and it seems to me that the whole question of covering them with anything
>>> is problematical.  If you come up with an answer, I'd love to hear it.
>>>
>>>
>>> Larry WO7R
>>>
>>>
>>> On Sat, Nov 16, 2013 at 6:24 AM, Patrick Greenlee
>>> <patrick_g at windstream.net>wrote:
>>>
>>>   Roger, Your UV is not nearly the intensity of the 5000 ft high desert
>>> QTH.
>>>
>>>> What works for you will not work with the intense UV of the high desert.
>>>>
>>>> Ray, I think the dripline is something to consider. I think it should be
>>>> much more survivable than typical water hoses which the UV eats quickly.
>>>> I
>>>> have had HD clear plastic tubing turn to sticky goo in under a year. I
>>>> have
>>>> used some 1/2 and 3/4 inch black plastic tubing in drip systems and it
>>>> lasted with no apparent damage for several years. The black plastic wire
>>>> covering "tubing" (wire loom) with a slit on one side lasts for several
>>>> years.  I always found it necessary to put some tape around it every so
>>>> often or to use a few distributed tie wraps to keep the enclosed wires
>>>> from
>>>> popping out when the bundle was flexed. Maybe you could ferret out the
>>>> mfg
>>>> and buy it in longer lengths that the shorter ones at the auto parts
>>>> store.
>>>>
>>>> Patrick AF5CK
>>>>
>>>> -----Original Message----- From: Roger (K8RI) on TT
>>>> Sent: Saturday, November 16, 2013 2:27 AM
>>>> To: towertalk at contesting.com
>>>> Subject: Re: [TowerTalk] Bundling of tower coax and control lines
>>>>
>>>>
>>>> On 11/16/2013 2:51 AM, Ray Benny wrote:
>>>>
>>>>   The subject of bundling tower coax with a spiral/twist type material was
>>>>
>>>>> recently mentioned. I cannot seem to find it.
>>>>>
>>>>> I would like to bundle my coax and other cables, hanging from coax arms,
>>>>> to
>>>>> protect them from UV rays. My QTH is high desert, almost 5000 ft
>>>>> elevation
>>>>> and control lines on other towers are starting to be affected. I used
>>>>> non
>>>>> UV resistant cables that I had on hand at the time,
>>>>>
>>>>>
>>>>>   My Opinion:
>>>> Because of the cost and work involved, I'd choose to just replace the
>>>> cables.
>>>> There are very few coax cables and rotator cables that are very
>>>> sensitive to UV.
>>>> The only brand name coax sensitive to UV "that I know of" are the
>>>> UltraFlex versions of the LMR series.
>>>> I do have "old" rotator cables that the outer jacket is failing after
>>>> nearly 30 years.
>>>>
>>>>
>>>> If the cables have been up long enough to already show substantial
>>>> deterioration, it's time to replace them anyway.
>>>>
>>>> 73
>>>>
>>>> Roger (K8RI)
>>>>
>>>>   Does anyone have leads to locate some of this UV resistant material?
>>>> I've
>>>>
>>>>   seen this type of material for indoor cables, in 6 - 8 ft lengths. I'm
>>>>> hoping someone makes long lengths, 50 ft or so and of different
>>>>> diameters.
>>>>>
>>>>> Just a thought, has anyone successfully used large diameter black water
>>>>> drip line for this? Seems to cover 2 RG8 size coax cables, a #12/2
>>>>> copper
>>>>> line and a 3/8" control line would require at least a 1" diameter line.
>>>>>
>>>>> Tnx,
>>>>>
>>>>> Ray, N6VR
>>>>> Chino Valley, AZ
>>>>> _______________________________________________
>>>>>
>>>>>
>>>>>
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>>>>> TowerTalk at contesting.com
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>>>>>
>>>>>
>>>>>
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