My **GUESS** is that it's a deterioration of the surface portions of
the copper, decomposition by-products of the inner insulation, held
against the copper surface for extended periods, never washed off by
rain, with active acidity restored over and over by rain. I don't
think that any possible degree of dielectric loss in the insulation,
deteriorated or not, could account for the degree of loss.
My current sketchy estimation of a workable experiment would be to
create a 40 meter dipole of the stuff, support it up 8 feet on conduit
tubing. Get some end tension so you don't change any positioning when
you start working the steel wool. Also wait for a dry day at the end
of a dry week, with no weather change or precipitation in sight.
AIM4170 RF analyzer, recording the graphs and saving the scans.
To attach a plain jane SO239, see if the deteriorated copper can be
soldered to. Note this and then steel wool if needed just right at the
solder points.
Measure at the center, then do a series of things... 1) steel wool the
non-copper stuff at the surface, still leaving the copper dull and
etched. Remeasure. 2) steel wool the copper bright on one side of
center. Remeasure. 3) steel wool the copper bright on the other side
of center. Remeasure. 4) while using the steel wool, note if the
resulting wire is even or has aspects of irregularity. 5) put a
micrometer on the wire before and after steel wooling the copper.
The AIM4170 utility will allow overlaying the R and X graphs, to show
if VF is changed on the wire.
The degree of loss change should show easily, even on the less
sensitive dipole test.
The loss was measuring out at an average ohm per foot. On the dipole
the dipole test R value might do something like drop from 165 to 100
or the like.
This is workable, and think there is enough of the wire from the test
site left. Hope he hasn't tossed it yet, but will see.
73, Guy K2AV
On Wed, Dec 28, 2016 at 12:30 AM, W0MU Mike Fatchett <w0mu@w0mu.com> wrote:
> Just curious if you think this is just a skin effect and if you were to use
> steel wool and shine the copper up after stripping if the copper acts
> normally or is there something happening chemically or atomically?
>
> W0MU
>
>
>
>
> On 12/27/2016 10:01 PM, Guy Olinger wrote:
>>
>> On Tue, Dec 27, 2016 at 7:49 PM, Rob Atkinson <ranchorobbo@gmail.com>
>> wrote:
>>>>
>>>> What IS complicated is how so many clearly have some kind of stake in
>>>> it NOT being true.
>>>
>>> I wouldn't call it "some kind of stake" as much as simple doubt
>>> because what you assert is, to be charitable, unsupported by
>>> observation.
>>
>> "Unsupported by observation" You jest?
>>
>> The disintegration is very much supported by measurement and
>> observation. Those measurements, and the methods used, are recently
>> posted on this reflector.
>>
>> I would also counter that durability outdoors, **particularly** given
>> THHN is not manufactured to this use, and forbidden for wet
>> environments in the NEC, is no more than an **assumption**. If THHN
>> were misused in this way in a professional setting it would be
>> considered an outright error in judgement. Certainly outdoor exposed
>> THHN would flunk an electrical inspection, with all the delay and cost
>> penalty involved.
>>
>> So just why is THHN durability in outside environment given the free
>> pass to skeptical treatment?
>>
>> I'll go back to the charitable "some kind of stake" because I really
>> do not get it.
>>
>> 73, Guy K2AV
>>
>>>> Someone with a low band dipole in the air using unstripped THHN may be
>>>> paying quite a penalty, especially if it's been up a long time.
>>>
>>> How long is "a long time?"
>>
>> 2,3,4,5 years perhaps to get to the extreme deterioration we measured.
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|