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Re: Using HV COAX without stripping the shield



Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi Ed, Gerry, all,

While I'm not denying the Blumlein factor, as I have stated
before, I have personally never experienced this with my
x-ray cables, with the shielding intact and grounded. OTH,
the problem that I see with removing the grounded shielding
is that the exterior of the insulation can still be charged and
you can still get a nasty shock when energize from your natural
capacitance. That's the whole idea of having a grounded
shielding around it in the first place, right? So, what is one to do?
If you leave the shielding intact and ground it, you risk Blum-
lein run-away voltage but if you remove the shielding, then you run into a serious shock hazard if you come in contact
with the exterior of the insulated cable while it's energized.
Well, "I" choose to give my own personal safety a higher prio-
rity than the safety of my coil components. I can replace coil
components, but I can't replace "me"! And since I have
not personally run into the Blumlein issue as of yet, "I" will continue to use my x-ray cables with the braided shielding
intact and grounded as my transmission lines. Of course I guess one could say that you have no business "touching" the exterior insulation of the transmission lines while energized
anyway.
David Rieben


----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, November 04, 2005 4:38 PM
Subject: Re: Using HV COAX without stripping the shield


Original poster: Esondrmn@xxxxxxx
I use RG213 for feed lines to my pole transformer. With the outer vinyl jacket and braided copper shield removed.
Ed Sonderman
In a message dated 11/3/2005 4:28:11 PM Pacific Standard Time, tesla@xxxxxxxxxx writes:
Original poster: "Mike" <induction@xxxxxxxxxxx>
Hi Gerry,
The DR. is right, if you want to stop the voltage
gain in the coax, to stop the Blumlein effect, remove the shield.
Likely you are using RG8 because the inside conductor is jacketed in
fairly good/heavy plastic or these days, foam.
You cut away the shield, you've removed the ~ 29 pf per foot (forgot
the value but think that's it) and without the coaxial C you loose
the ring back power gain.
Google and check out Blumlein power supplies, nice way to 2 X or 4 X
or more, your pulse power. Used in some big pulse systems.
Termination Z is important on the line for full effect, also it is
possible to get reversal of polarity on a DC pumped system and you
can design that in or out.
Some systems have used a larger counterpoise around most of the
center line sides but not 360 degrees, I think U of Texas HV lab did
a lot of work in this area.
Very fast lines, though, if your looking for high current and voltage
gain. The networks you spoke about would need to take the ~ 300 amp
at 2 X voltage and sink it.
Cure sounds worse than the problem. Skin the coax else use it as a
power supply component.
Mike