[Amps] Glass Tape more

[Edwin Karl]

I am specifically referring to Scotch #27 Glass Cloth Electrical Tape
(or so the box says). Rated to 266 degrees F. Used in furnace, oven
controls and switches.

I use 1/2 inch size because it's easier to wind on the ferrite core.
The specific application put the insulating material inside a 50 watt 
resistor,
which would make a mess with ordinary #33 black stiff.

When I built a balun for ladder to coax transition, wound the tape on a 
heavy
balun core compliments of "the Wireman", see his catalog. After the balun
was built, I further coated it with several layers of epoxy. Fastened to 
perfboard,
mounted about 3/4 " from each wall of a copper box, made from PC material.
Beehive insulator output, type "N" input. Hasn't failed in over 6 years.

I never used the tape outside, inside a UV oven, etc. Just as an 
insulator, or in
the case cited as a spacer and insulator.

That's my story and I'm stuck with it ...

73!




On 7/28/2013 11:00 AM, amps-request at contesting.com wrote:
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>     1. Re: Glass Tape (Manfred Mornhinweg)
>
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 27 Jul 2013 17:23:05 +0000
> From: Manfred Mornhinweg <manfred at ludens.cl>
> To: amps at contesting.com
> Subject: Re: [Amps] Glass Tape
> Message-ID: <51F401F9.6070903 at ludens.cl>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi,
>
>> Glass tape usually turns to dust in UV sunlight.
> I think Carl means that glass fiber reinforced, plastic adhesive tape.
> That stuff indeed turns to dust rather quickly. Dust with loosely
> embedded glass fibers. Even when used indoors, in dry climates the glue
> crumbles rather soon, in my experience.
>
> But I'm under the impression that Ed means a different material, one
> that is just glass fiber fabric, without any plastic or glue in it. Is
> that right? Such a material should survive UV without trouble.
>
> For winding baluns, I use one of two different techniques to avoid the
> wire insulation chafing through. One is to wind the balun with
> plastic-insulated wire, with the insulation being thick and hard enough
> that it won't puncture. Common THHN house wiring stuff is fine. It also
> gives me more confidence when working under high power, elevated SWR
> conditions, when the voltage between wires can reach the kilovolt level.
>
> The other technique is to wrap the core, but instead of glass tape, I
> use several layers of black vinyl insulating tape. This tape MUST be
> good quality. Since about 30 years I use Scotch Super 33+, and I can
> fully recommend it. There must be other good tapes available, but when I
> tried, this was the one that worked best among all the ones I tried, and
> as long as it is available, I see no reason to search for another! I
> have some antennas that are over 20 years old, fully exposed to the
> weather, with this tape used in several locations, and it's still fine!
>
> I have read lots of warning about using PVC in RF fields. This
> insulating tape, and most plastic wire insulations, are PVC. So I was
> always a bit scared that something terrible might happen, like an
> insulation meltdown, but so far it hasn't. I wouldn't use a thin sheet
> of PVC as a capacitor dielectric, but in the form of wire insulation or
> a toroid core wrap it seems to do fine enough.
>
> Black is best, for the wire insulation too. It blocks UV and largely
> prevents degradation beyond the surface layer of a plastic.
>
> Manfred
>
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