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Re: NST Death
Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Kidd6488-at-aol-dot-com>
>In a message dated 7/7/01 12:07:37 PM Eastern Daylight Time, tesla-at-pupman-dot-com
>Can someone explain to me why ARSGs are so bad for trannies? Robert Krampf
>does shows with his NST powered coil, and uses an ARSG! He's done this for
>years with the same NST.
If you do everything right there is no problem. If you do one thing wrong,
BLAMO!! Bye bye NST...
Now days, most people use NST filters, safety gaps, MOVs, etc. that go very
far in saving the NST no matter what else one does wrong. In the old days,
they used maybe a choke, which doesn't do a darn thing (IMHO). If they had
a good safety gap, then they had to be sure to set it right. Problem is,
that async gaps need twice the BPS rate of a sync gap to get the same power
throughput (240BPS). Many people saw the short sparks and started opening
the safety gaps... A sure way to kill an NST since 90% of these systems
used resonant sized caps. If the BPS rate was too low, the static gap
would fire like crazy. Often people fiddled with opening the safety gap at
that point and... Or, they where playing with the BPS rate and let it fall
too low (which gives larger sparks do to the system overcharging) and they
turned the BPS rate down until the NST blew.
Basically, there are a ton of opportunities to destroy an NST with an async
gap and a resonant system. Today, we push LTR systems and safety gaps if
not the full blown RC MOV protected filters. Also, we tell people to NEVER
mess with a safety gap unless they like barbecuing NSTs... This really
helps the new coiler in that they can do most things totally wrong and the
NST will survive. I think if good filters, protection circuits, and LTR
caps sizing was available back then, that async gaps would not have gained
such a bad reputation. But as it turned out, people would hook up a new
async gap and blow four NSTs in an hour. The reports of how well they
liked their new async gaps were very unkind...
Personally, I don't like async gaps. They are too "random" for my taste.
They are also a bit hard to match well to a cap for a wide BPS range with
an NST (pig systems just turn up the current to suit). Sync gaps are
almost as easy to make now that we have great instructions and friends to
tell us how to grind them in an hour or so with a file... "I" think sync
gaps are far better...
Today, we know much more and our suggestions and designs have many safety
features built in to help new (and old) coilers avoid many problems. We
used to kill NSTs all the time until we looked into "why" and simply fixed
the problem with well designed filters that even a newbi can't screw up
:-)). MMCs have pretty much fixed the cap problem and now they are even
cheaper than practically every other cap type (even salt water)... They
can also get over voltaged and came back for more... This list used to be
filled with people building rolled poly caps and wondering how thick to
make the poly and all that. When is the last time you heard of anyone
making a rolled poly cap these days :-)) So a lot has changed and the poor
reputation that async gaps have is a bit undeserved. But back then, it was
like pouring gas on a coil that was already on fire...
I bet Robert has all this figured out :-)) and he shows that it can be
done. However, the typical new async gap user has maybe 25 years less
coiling experience than Robert. ;-)