Re: Coax Cable for High Voltage?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Jim, all,
            My pet hates about coax used in coiling are that it is 
nearly always used in an unmatched situation with high power step 
functions flying around (it is a transmission line at those 
frequencies and therefore develops nasty resonances and high voltage 
rings) and for many types, the braid is a total loser if it is 
included in otherwise high Q circuits. My pet hates do not include 
its voltage rating which is usually very good except for the types 
with foamy or air-spaced inner dielectrics. My advice: steer clear of 
it.

Malcolm

On 28 Feb 01, at 7:58, Tesla list wrote:

> Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <jimlux-at-earthlink-dot-net>
> 
> 
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Tuesday, February 27, 2001 6:14 PM
> Subject: Re: Coax Cable for High Voltage?
> 
> 
> > Original poster: "R Lunsford by way of Terry Fritz
> > <twftesla-at-uswest-dot-net>"
> <Millipede-at-carolina.rr-dot-com>
> >
> > As far as the coax goes, I personally wouldn't use it. I really
> > isn't designed for it.
> 
> To the contrary, most larger coax cable is designed for high voltage. 
> In fact, they are rated at a variety of voltages 5000 VRMS would be
> typical for RG-213/RG-8 series, with 11000Vrms for the next size up. 
> And, recall, that that rating is for use in a transmitter, where you
> might have standing waves that are substantially higher.
> 
> I wouldn't try running HV down RG-174 of course, and as previously
> pointed out, I would stay away from the various foam insulated
> varieties (RG-8X, 8813, TMR400,etc.), although, by definition, those
> probably have the same ratings, since they are intended as "work
> alike, but lower loss" replacements.
> 
> A fairly quick calculation of the field strengths will show that
> RG-213 can take a fairly high voltage.
> 
> I personally like grounding the shield, because it makes the field
> more uniform, and provides a safety aspect that if there is a fault in
> the dielectric, it's going to short/arc/spark to the shield, not my
> hand.
> 
> 
> 
> 
> 
>