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

[Edward Mccann]

Unless K2AV has developed a new recipe for the secret sauce in how he strips wire, here's   his then-current view in 2010 from a post to Topband 30 September 2010:

"To convert convert cheap wire (PVC insulated THHN, etc) to more expensive and harder to find bare wire, simply strip the insulation. (THHN is a volume item, bare is a specialty item.) Using a dull pocket knife it is possible to strip 500 feet of #12 THHN in no more time than it takes to walk the length. Sharp knives dig into the copper when the angle of the blade to the wire is increased enough to keep the blade underneath the insulation while stripping. You can straighten the wire sufficiently for stripping by pulling the wire off the reel, through a pulley under tension for 180 degrees, and back the other way. This works, I have done it many times."
Stay away from those sharp knives, and don't take your guns to town boys, leave your guns at home.

As far as the "Measurement they are, and Measurements they is, and we're stuck with them," I would also be interested in the measurements, and look forward to learning more about this.

73
Merry Christmas 
AG6CX


Sent from my iPhone



Sent from my iPhone
> On Dec 25, 2016, at 7:15 PM, <john at kk9a.com> <john at kk9a.com> wrote:
> 
> Your post leaves me with many questions.
> 
> What are the actual measurements? What is the reason that PVC (which is
> pretty tough as well as moisture resistant) is causing this issue?  What is
> you method for rapidly stripping THHN?
> 
> John KK9A
> 
> To:    Towertalk <towertalk at contesting.com>
> Subject:    [TowerTalk] UV and WX deterioration of THHN insulation,    and
> effects at RF.
> From:    Guy Olinger <k2av at contesting.com>
> Reply-to:    k2av.guy at gmail.com
> Date:    Sun, 25 Dec 2016 03:50:11 -0500
> 
> First of all, and most important, a joyful holiday season and a prosperous
> New Year to all of you.
> 
> Now down to microscopic issues that will probably have no bearing on World
> Peace...
> 
> Let's be clear that I stand by my prior statements against using unstripped
> THHN at RF, respectfully, others' contrary statements notwithstanding.
> 
> We have careful measurements. We can't just walk away from measurements. A
> measurement is a measurement, not an opinion. We're stuck with
> measurements.
> 
> The effect in one case, losses from deteriorated insulation on elevated
> THHN radials were the same as if one had placed a 15 ohm resistor between
> the coax center conductor and the vertical wire. ***The owner was unaware
> and thought everything was fine.*** How this came to light is an involved
> story.
> 
> 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. It would
> have developed very slowly, very sneaky. Not like having a branch drop on
> your antenna and having the SWR suddenly go bonkers.
> 
> I find the defense for using UN-stripped THHN outdoors and for RF
> intriguing. Even more intriguing, stuck with the prospect that THHN might
> be bad for us, some propose going to a different (less common, more
> expensive?) THH-something variant hoping for a better insulation lifetime,
> while admitting the new THH-whatever will probably go down from UV as well,
> just later. ???????  You're hoping for what advantage from the insulation?
> 
> With the single exception being some posters to this reflector, everyone I
> know locally or have corresponded with, or talked with on the phone on this
> subject, they all bought a spool of THHN from a Home Depot/Lowes/etc for
> outdoor antenna wire because it COST LESS, maybe half the price of same AWG
> from sources that sold it as bare wire.
> 
> Likewise if they didn't strip it, the single reason they did not strip it
> was because it appeared to be a lot of work. Some tried to strip it but had
> the problem of the knife digging the copper. They had never seen a
> description of "the method".
> 
> It turns out that it is possible to strip 250 feet of THHN in the time it
> takes to walk the length of the wire, if you use the method. The limiting
> factor is the distance you have available to stretch it out before you
> strip it. Everyone who has seen it done, later says it's obvious once
> you've seen it. Once they have seen it done they all strip the THHN and put
> up the solid bare wire.
> 
> It's impossible to NOT take some hit with still-insulated THHN vs.
> stripped. If nothing else, they're out for the dielectric loss of the
> insulation.
> 
> Then there are potential gradually increasing losses as the UV deteriorates
> the material, with clearly proven examples of severe end-stage losses with
> the UV deterioration.
> 
> Happy Holidays everyone, and back to the egg nog.
> 
> 73, Guy K2AV
> 
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