Amidon is not the only supplier of #12 standard wall teflon (PTFE) sleeve.
They are just one I listed in the article who would actually sell someone
only 15 feet.
You should be able to get your length of standard wall PTFE tubing from
Asian markets easily without the overhead of US international postage. A
millimeter equivalent diameter that is not smaller than #12 will work. If
you use smaller than #12 sleeve, it gets difficult to push the #14
polyimide wire through the sleeve.
Remember that you are insulating one wire from the other wire.
Our accumulated experience here is with #12 standard wall teflon tubing.
It does two things.
1) It adds to the insulation value with a very low loss factor as a
dielectric.
2) It protects the polyimide coating on the wire from nicks. Polyimide is
great stuff for voltage breakdown, but it nicks easily. All you have to do
to ruin the polyimide is drag it on a concrete floor or drop the wound
toroid on the workbench, or have it rattle around in a bucket to get a
nick. The voltage will find the nick and the game's over.
Once you cut the polyimide coated wire to length and get the teflon over
it, it's protected. The combination wound over the #2 powdered iron may
last a lifetime absent a direct lightning strike.
We would rather have used less, but grudgingly worked our way through
failures up to this level of insulation, and trouble quit happening when we
finally got to double polyimide insulated wire and #12 standard wall teflon
sleeve. This is not an insulation level based on speculation.
Some examples of voltage stress on the winding: Wind static may be on one
wire of the winding and ground on the other. This is being used as an
isolation transformer, not a choke. Or loading power to the system on the
wrong band using a tuner to take out the SWR. The winding per the article
stands up to these stresses without damage.
73, Guy
On Sun, Nov 11, 2012 at 4:14 AM, Jo, YC0LOW <yc0low@gmail.com> wrote:
> I am in the process of homebrewing the FCP system for my own station.
> I already had three toroids from Amidon, USA, safely, but I forgot to
> put the Teflon Sleeveing for the #12 AWG in my purchase order. list.
> I tried to contact the Amidon and they are very helpful by already
> quoting the price of 55ft teflon tubing plus shipping/handling (with
> USPS Priority mail) costs to my address in Indonesia. The amount is
> US$ 75 - rather high for a retired person like me :-))
> The wire is available here. But, since I cannot find the the Amidon
> teflon sleeveing in Jakarta, I wonder if the tubing can be substituted
> with other material to isolate the two wires on the toroid, for
> example: heatshrink sleeve.
> How would it be performing, please?
> I'd be gratefull if you could advise to me. Tnx es 73 de Jo, YC0LOW
> _______________________________________________
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>
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