Re: NST phasing questions

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Mddeming-at-aol-dot-com>

In a message dated 5/26/01 1:46:40 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes: 



>
> 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 NST's, correctly phased = no/small sparks when NST 
> secondaries are touched together, incorrectly phased = big sparks. Is it 
> true that running NST's 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? 
>
> 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 irrelevant 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.* 
>
> 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 
>
>



Hi Jonathan! 
Yes, when properly phased, there should be little or no spark Little in this 
case means like you would see from a 6v or 9v battery or model train Xfmr. 
      If you connect two NST secondaries in parallel with different kV 
ratings you WILL burn one or both of them.  When NST's are matched in 
parallel, there should be no more than about 8-10V difference in their actual 
(not rated) outputs. Your 3 kV difference will definitely cause you grief. It 
is possible to match NST's of different current ratings, but NOT different 
voltage ratings. (i.e., 15/30 + 15 /60 + 15/120 is OK, but 12/60 + 15/60 + 
9/60 = FIRE!!). The way to test this is to connect a 1/4w 1K-ohm resistor 
between corresponding terminals of the NST's and run up the power. If the 
resistor gets hot or dies smoking, the NST's cannot be used together. 
Sometimes even NST's with the same RATED voltage can be a hundred volts or 
more out of match, and you will produce more heat and smoke than output 
current if you use them together. 
      I would connect NOTHING to the HV RF ground except the HV RF 
components (base of 2ndary coil, NST Protection ground terminal or grounding 
lugs of NST's, and strike rail. The line filter should be on the INLET side 
of your control box, connected to the mains ground, and kept physically and 
electrically as far as possible from any HV RF sources. If you have a power 
cord separate from your control box inlet for RSG or a blower, it should have 
its own filter too. Otherwise, you risk your PC, VCR, MW oven, TV, etc., and 
possibly your neighbor's stuff too, if you're on the same distribution Xfmr. 
:-P You might get by for quite a while, but it only takes once to make a real 
bad impression on friends and family. 

Matt D.