Homebrew insulators
 

"JIMMIE" wrote in message
...

I have found that just about any of the colored marking tapes dont
hold up well outdoors.

I assume you mean tapes like surveyors use as well as temporary tapes
printed with "Police Line" or "Caution." These are generally made of
polyethylene because it is so inexpensive. Exposed to ultraviolet light,
polyethylene is destroyed quickly.

To add to something "Dave" said, Dacron is DuPont's name for their brand of
poly(ethylene terephthalate) polyester fibers. Other fiber names are
Dacron, Diolen, Fortrel, Kodal, Tergal, Terylene, and Trevira. I have seen
hamfest dealers charging considerably more for Dacron rope just because of
the name. Likewise Mylar is DuPont's name for PET film, but PET films are
also known as Terphane, Hostaphan and Melinex by different manufacturers.

--
73, Dr. Barry L. Ornitz WA4VZQ

[transpose digits to reply]

Homebrew insulators
 

On Jan 27, 7:33*pm, "Dr. Barry L. Ornitz"
wrote:
"JIMMIE" wrote in message

...

I have found that just about any of the colored marking tapes dont
hold up well outdoors.

I assume you mean tapes like surveyors use as well as temporary tapes
printed with "Police Line" or "Caution." *These are generally made of
polyethylene because it is so inexpensive. *Exposed to ultraviolet light,
polyethylene is destroyed quickly.

To add to something "Dave" said, Dacron is DuPont's name for their brand of
poly(ethylene terephthalate) polyester fibers. *Other fiber names are
Dacron, Diolen, Fortrel, Kodal, Tergal, Terylene, and Trevira. *I have seen
hamfest dealers charging considerably more for Dacron rope just because of
the name. *Likewise Mylar is DuPont's name for PET film, but PET films are
also known as Terphane, Hostaphan and Melinex by different manufacturers.

--
73, Dr. Barry L. Ornitz *WA4VZQ

[transpose digits to reply]

Sorry I thought I had quoted Jeff and it was understood I was talking
about PVC electical tape.

Jimmie

Homebrew insulators
 

On Sun, 25 Jan 2009 18:31:31 -0800, "Tom Donaly"
wrote:

NoSPAM wrote:
"JIMMIE" wrote in message
...
I came across an old single LPDA TV antenna in the trask. It was
pretty much FUBAR except for a coupe of feet of boom matrial and a few
insulators. My XYL is into making models and castings and she can make
a mold of the insulators easy enough. I was wondering if anyone knew
of a good casting material that would be compatable with the
requirements to build a single boom LPDA antenna to form the
insulators. She is not usually concerned with strength or UV
resistance so she couldnt help much on this part.

Epoxy and polyester resins come to mind. If you are rebuilding the TV
antenna and not adding significant weight, these should work well. Use
the low viscosity resins sold in quarts, and not epoxy glues.

For added strength, consider adding chopped fiberglass strands. For
reduced weight, glass microballoons may be added to the resins. They
are extremely light with a specific gravity of 0.18 to 0.25 depending on
the manufacturer. Phenolic microballoons are also available.

For ultraviolet protection, a small amount of titanium dioxide may be
added (1 to 5%), but the microballoons will do a fair job alone.
Painting the finished insulators with acrylic paint (Krylon®) will also
provide good UV resistance.

Many marine supply stores carry these resins, the chopped fiberglass,
and the microballoons. Be extra careful with the polyester catalyst
(typically methyl-ethyl-ketone peroxide) as it is extremely damaging to
the eyes.

Good luck with your project.

73, Dr. Barry L. Ornitz WA4VZQ
[transpose the digits to reply]

Where do you buy the titanium dioxide?
73,
Tom Donaly, KA6RUH
I use http://www.acp-composites.com/ACP-CAT.HTM

John Ferrell W8CCW