Re: NST phasing questions

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

Original poster: "Bill Vanyo by way of Terry Fritz <twftesla-at-qwest-dot-net>" <vanyo-at-echoes-dot-net>



Tesla list wrote:
> 
> Original poster: "Jonathan Peakall by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jpeakall-at-mcn-dot-org>
> 
> Howdy All,
> 
> Before I go do something stupid, I just thought I'd check to see if I
> have this right... I did read the phasing FAQ, but I want to be sure.
> 
> When phasing NSTs, correctly phased = no/small sparks when NST
> secondaries are touched together, incorrectly phased = big sparks. Is it
> true that running NSTs out of phase won't hurt 'em? I have a 15/60 and a
> 12/120, and some sources say that I can gang them up in spite of the
> voltage difference and some sources say I can't. What's the opinion
> here?

I don't know about voltage diffs, but I did get a 15/30 and 15/60 phased
properly.  One odd thing though was that I couldn't get them to phase if
I hooked the primaries in series (as has been suggested on somebodies
Tesla coil page) - *neither* side of either secondary was nearly in
phase with *either* side of the other secondary.  But with primaries in
parallel, it worked fine.

> On another subject, one does hook up line filters backwards with the
> ground terminal connected to RF ground, no? I searched the archives, but
> they seemed to be behaving oddly, I would hit a link to a relevant post,
> but I would get an irrelavant post, like about pole pigs or torrids.
> It's never done that before, so Terry if you read this, you might want
> to check it out.*

I'd like to see this one answered definitively.  I'm using line filters,
but not backwards, as a recent discussion here suggested that the
purpose of a line filter *IS* to protect the line, and not the
equipment, though to me that doesn't seem logical (one faulty device
pollutes the line, and everything else is unprotected).  Recent
discussions also said most EMI filters are symmetrical so that it
wouldn't matter anyway, but mine (Sprague) are not - and not being such
a wiz with electronics, I can't figure out from the schematic which side
they are protecting - line or load, or whether the assymetry even
matters.

The more interesting question to me is what to ground where.  Take a
look at everything that needs a ground connection:
1) Secondary base.
2) Strike rail, if present.
3) NST case/secondary midpoint.
4) NST protection filter and/or safety gap.
5) Line filter.

One web site called it a "deadly" mistake to ground the NST case to the
RF ground.  Right now, I have 1 & 2 above hooked to RF ground, and 2, 3
& 4 hooked to a seperate spike in the ground (2&3 to one spike, 4 to
another) -  just a really big nail (10") in damp earth.  Not that I
recommend that - I'd like to hear what the experts recommend.

> 
> Thanks y'all,
> 
> Jonathan Peakall
> 
> * I did a search on >"line filter" hookup< and it seemed to work well.  Put
> quotes around "line filter" so it knows to consider that as a single phrase
> and not two words. - Terry