Stefan,
If you ever become interested in encapsulating an HV coil, I can send
details for a straightforward process for low-cost/lightweight encapsulation
that gives 10-year life in harsh outdoor environments with 10kV per inch
across the problematic smooth surfaces. The dielectric is 450V/mil but the
issue for lightweight long HV life in harsh outdoors is smooth interfaces
between dissimilar materials, and this straightforward low cost process
solves the problem. No special equipment needed. Decades of good field
history with this process, no issues.
73,
Jim AA5BW
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of DK7FC
Sent: Wednesday, December 28, 2016 4:00 PM
To: [email protected]
Subject: Re: VLF: New coil for 8270 Hz
Am 28.12.2016 19:00, schrieb [email protected]:
> PS Stefan's coil is very compact. 0,4 mm wire? Hope it can take the kV!
Hi Joe,
Yes, 0.4mm wire. The voltage is not the problem for the wire. But the tube
is out of PVC and the length of the winding is about 0.3m. So it will be
about 1kV/cm which could be problematic if the inner side of the tube
becomes wet, inhomogeneous wet. This could cause strong local E field
strength which leads to arcing on the surface. Arcing on the surface makes
the surface conductive, a self accelerating process that can be repaired.
This is the high risk of this construction! It has its advantages and
disadvantages. It will handle 700 mA RF current, at least now in winter :-)
But i should take care to keep it as dry as possible.
We will see what happens.
73, Stefan
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