Hello Dave and others,
Tnx for all these infos !
I don't know what type of Teflon i have... so i expect to have the cheapest
one ! :-)
In the design i have, the lower part of the sandwich is a few mm larger than
the upper one, so if i cover the lower one completely with the Teflon sheet
(or even beyond the borders) there should be a bit more protection against
RF arcing.
Also special care should be taken to have best surfaces as possible with no
air bubble or bits of swarfs.
Tnx for all mails abt the subject.
73, Patrick
2005/9/16, Dave Bowker <dbowker@mail.sjv.net>:
>
> Pattrick,
>
> It depends upon what type of Teflon you have.
>
> Polymerized tetrafluoro ethylene (CF2.CF2) has a dielectric strength of
> 1000 volts per mil (.001").
> Fluorinated ethylene-propylene (Teflon FEP) has a dielectric strength of
> 3200 volts/mil and is
> usually found in thin film applications.
>
> Assuming you have the polymerized type (most common in thicker sheets),
> 0.5 mm would equate to
> 0.0196" (20 mils) for a dielectric strength of 20 kV.
>
> One thing to be aware of when using in "sandwich" applications where there
> is RF across the plates
> as well as DC, is that there is a very high probability of arcing across
> the edges of the plates if
> the Teflon insulation does not extend beyond the dimensions of the plates.
> This is even more
> prevalent at VHF and above than at HF.
>
> 73, Dave, K1FK
> Fort Kent., ME
> ARRL Life Member
>
>
>
--
TK5EP
Patrick Egloff
http://tk5ep.free.fr
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