[TowerTalk] UV and WX deterioration of THHN insulation, and effects at R

[Rob Atkinson]

>
> "Unsupported by observation"   You jest?
>

No.  By the way I gave you a pass on your snake oil FCP nonsense too
but now I'm expecting you to try telling folks that the plastic on the
wire _holds the RF in._  And I bet some will believe you.

> The disintegration is very much supported by measurement and
> observation. Those measurements, and the methods used, are recently
> posted on this reflector.
>

In science there's a thing called repeatable experimentation.  I'll
wait for someone else to perform your measurements and report in a
publication that has been vetted in some journal like QST, although
QST is not exactly a pillar of technical refinement these days.  How
about some searches for factual data in IEEE journals?  Never mind, I
can do it, except I have a life and real problems not made up ones.

> 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.
>

blah blah blah hot air.


> So just why is THHN durability in outside environment given the free
> pass to skeptical treatment?
>

Maybe because it's ham radio antennas?  You know, a hobby?


>
>>
>>>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.
>

Yeah, that's what I thought.  My newest house wire antennas have been
up since 2009; balanced feedline made with AWG 16 has been outside
since 2003.  You'd think I'd see differences in matching network
tuning over that time.  The system is entirely stable.  The usual
great signal reports even with my Knight T-50.  Whenever I go out
there to make a repair I find nice shiny copper under the insulation.
Ditto for the AWG 14 solid radials with the insulation on them, which
Archibald Doty in his paper on ground systems advised leaving on for
improved performance.*  Interesting how hams have been improvising
with this wire for antennas, for probably around 50 years, maybe more,
and no one ever knew there was a problem with it until some ham on a
ham email list announces he thinks it doesn't work, claims he's made
measurements which have not been made by anyone else, and the suckers
start getting out their Xacto knives.  Okay, nothing else to see here
folks, Happy New Year.

73
Rob
K5UJ

* Performance of Conventional Buried Wire Radials Versus Elevated
Insulated Radial Wires Used As Ground Systems For Vertical Antennas.
Archibald C. Doty, Jr.
Presented at Meeting of Radio Club of America, Nov. 18, 1983