RE: Where to get 4kv 20ma NST?

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

Specifying a VA rating rather than a specific transformer would seem fair
and to allow wider competition, but I fear that the underlying intent would
be compromised - that being to ensure that all start with the same basic
power supply, with innovations and efficiencies being made downstream.  A
different NST of the same volt/Amp rating may have different shunt
configurations and (removing) different shunts will surely have a profound
effect on performance.  Also, it has been widely suggested that higher
voltages have an inherent efficiency advantage, so an 8kV/10mA may be more
efficient than a 4/20, despite having the same VA rating.

But I would hate to keep folks from participating just because they don't
have a source for the "official" NST.  I think it's more important to get a
wide participation than to enforce the rules to the letter, as long as you
start with a reasonably close approximation to the official NST and are up
front about it.  This is more about innovation than competition and there's
no final judging date or cash award involved.  I'm thinking that the
results would simply be tabulated on a web site with streamer-length
ranking, brief specs, photos, and an optional URL to more details, with a
note as to whether each coil did or did not use the "official" NST.  Or
maybe tabulate close but non-official NST entries separately.

Shad, you mention a 4/30, but the competition calls for a 4/20 NST.

This has to be disruptive-mode only.  It would be futile to attempt to get
longer sparks from a CW coil with the same input power.  I'm on the fence
as to whether a static gap should be required or whether RSG's should be
permitted.  I wanted to make sure that folks weren't abusing their NST's
and pushing them way past their safe limits by opening their gaps too wide,
and was even thinking of specifying a maximum gap width (0.050").  Static
gaps would be more in keeping with the nature of table-top coil sizes,
being not too complex.  If RSG's did turn out to be more efficient, it
would be a shame to not explore and exploit this, but I'm leaning to not.
Other thoughts?

I did have an off-list discussion with Dan and indicated that I felt that
magnifier configurations would be legitimate should someone be so inclined.

I don't think it's practical to specify wall-plug power.  Most of us aren't
equipped to accurately measure true RMS power, particularly when using
static gaps.  Better to just specify the NST faceplate rating so we don't
have to fret over power factors and chaotic waveforms.

Gary Lau
MA, USA



Original poster: "sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<sundog-at-timeship-dot-net>

Well now, this sounds like a fun little competetion!  I've given up on 
claiming the GMHEICSLR cup.  11" is the best I can manage before my coil 
self-destructs (inter-turn shorts in the primary).

   I'll try to dig up a 4/30 (I may have one already, IIRR, may be 6/30).

     To keep it all sane, we should get a list of people willing to be 
involved, choose somebody to organize and judge the results (preferably 
somebody not participating), and set the rules.

   So far, we've limited the supply to 80w input power.  Wow :)  Next, I 
suppose we should set the rules on types of coils allowed.  Is this a 
demonstration for disruptive coils only, or can we get enough competition 
to merit SGTC's, SSTC's, and VTTC's in there?  Coils this small will be 
cheap to make (caps and the transformers will be the most expensive 
parts).   In the interests of innovation, I'd rather set a limit on the 
total input power to be 80w, as measured at the wallplug.  That should not 
include cooling fans for the spark gaps, etc.  Just the power going to the 
transformer.

   Maybe if there's enough interested people, we could organize a bulk-buy 
of 4/20's?  Perhaps get a better price, and level the playing field by 
everybody using the same tranny.  Then it comes down to builder's skill and 
efficiency of the rest of the coil.

   And we'd have to pry Terry away from his OLTC to make us a trophy ;)  He 
did such a good job on the GMHEICSLR trophy (which still eludes me!)

Sounds like a blast to me :))


Shad
G5-1203


Original poster: "Malcolm Watts by way of Terry Fritz 
><twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
>
>
>Can I suggest that a VA rating is a more appropriate platform off
>which to launch a competition? Franceformers aren't very plentiful in
>my part of the world.
>
>Regards,
>malcolm