Re: Using HV COAX without stripping the shield

["Tesla list" <tesla@xxxxxxxxxx>]

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