Re: Terry Gap vs. TCBOR...

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

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 


If you are running a pri cap value of 1.6 * Cres the xmfr will be working
hard to supply the recharge current.  In short, extra available current to
cause power arcing will usually not be available.  If running at Cres, or
below this value, the xmfr has enough additional current after charging the
cap to possibly cause power arcing.

This also depends on the type of spark gap you are using.  I've found that
the standard 1/2 inch dia. tungsten electrodes we use have enough surface
area to do a good job of quenching without power arcing.  1/8th inch dia.
tungsten rods may heat to high local values especially near the edges which
could also lead to power arcing.  One indication of this problem --- if your
sec. sparks seem to "shrink" after 20-30 sec. of operation.  With good
quenching and heat dissipation the sec. spark will usually maintain it's max
spark length.

If you use a large surface area in your sparkgaps power arcing should not be
a factor.  With 60 mA NST usually 2 series gaps of 1/2 dia. or greater work
fine.  At 60 mA with 2 gaps we never use a blower.  At 120 mA or above a
blower is necessary with static gaps --- a better choice at this power level
is a synchro setup.

I'm looking foward to the Terry Gap vs. TCBOR gap report.

Dr. Resonance

 >
 > I already covered this in one post, but in the fear
 > that it might start one of those tangents which cause
 > a thread to lose relevance to its original subject...I
 > have to say that in 5 years of running many different
 > types of static gaps with coils using a 12/60 or
 > smaller powersupply, I can assure you that airflow or
 > lack thereof will not effect this test.  It was
 > definately something worth pointing out, but in this
 > case it won't matter.
 >
 > I've seen powerarcing occur in several gaps when no
 > airflow is present, and in no case (in my system) did
 > it ever occur instantly.  There was always a marked
 > decline in output which coincided with heating in the
 > gap.  I plan on taking the scope readings well before
 > powerarcing due to gap heating begins to take place.
 >
 > Thanks,
 > -Brett"
 >
 > My real interest was whether epoxy cement could stand the temperature.
 > In the gaps I've made I mounted the pipes on either ceramic insulators
 > or transite sheet, which could stand pretty high temperatures but the
 > idea of gluing them in place (or using PVC pipe as in some of the blown
 > types) is quite appealing.  Others have reported good success but I've
 > always been too chicken to waste the time.
 >
 >
 > Ed
 >
 >
 >