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Re: New Testing


From: 	Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
Sent: 	Thursday, September 11, 1997 2:24 PM
To: 	Tesla List
Subject: 	Re: New Testing


> From: 	Esondrmn-at-aol-dot-com[SMTP:Esondrmn-at-aol-dot-com]
> Sent: 	Wednesday, September 10, 1997 7:55 PM
> To: 	tesla-at-poodle.pupman-dot-com
> Subject: 	New Testing
> 
> Well, I fired up my coil again tonight after a few months of
waiting for the
> replacement Condenser products capacitor.  It arrived a few days
ago and was
> installed with a spark gap across it set at about 1.0".  I also
recently
> rebuilt my ground system using solid copper flashing to
interconnect all the
> ground rods and to the base of the secondary - only maybe 4.0 feet
from the
> base of the secondary to the ground system.
> 

Yes, it is always a good idea to protect the capacitor with its own
local safety gap. Some people think that because they have safety
gaps on their transformer, they don't need it on their caps. Better
safe than sorry, I say! I am a firm believer in putting the
protection as close to the thing I want to protect as possible. When
I play around and exchange caps from one TC and another the safety
gap goes right with the cap. The two are inseparable as far as I am
concerned. My transformers have their own safety gaps, usually
mounted right on the transformer so they don't get "lost".

> Using a 14.4 kv, 5kva pole pig and a 220 amp lincoln welder with
superior
> powerstat for primary power.  I have a switch system set up to
switch in
> resistor elements in parallel with the welder.  All switches off is
22 ohms
> in parallel with the welder and all switches on is 3.3 ohms in
parallel with
> the welder.  I set the welder on low and the rotary on low speed.
> 
> When I first powered it up, the primary current in to the pole pig
was about
> 12 amps.  The gaps would only fire erratically even at full variac
voltage.
>  I tried switching in more resistive load in parallel with the
welder and the
> gaps almost quit firing altogether with all elements on - about 3.3
ohms.  I
> unplugged the resistive element bank so the welder was on it's own.
 As I
> increased the variac voltage, the gaps started firing erratically
again and
> the spark gap across the main (.025 mfd) cap started firing. 
Someone said
> this would be very loud and they are right, no mistaking if it is
firing or
> not.
> 

BANGGGGGG! And it reverberates in your mind for a while!!
But if the gap across the safety on the cap is firing, then that
means that your regular spark gap must be open larger than the safety
gap. You ain't supposed to do that, Ed!!! Sounds like the sum total
of rotary and series gaps is excessive. Try reducing the number of
series gaps.

> I tried different tap settings on the primary and did not have much
luck.
>  Still can't get the gaps to fire smoothly.  The coil is trying to
tell me
> something and I just don't seem to get it.  I have been having
problems with
> this system for the last year, every since I rewired all the
primary
> interconnects by replacing the wire (two pieces of RG213 in
parallel) with
> 3/8" copper tubing.  This coil used to run very well and has
produced 80"
> discharges.
> 

Did you try firing the gaps with the primary winding shorted? If they
won't fire that way, then there is something truly strange going on.
You also didn't mention whether the secondary was producing any arc
when the gaps DID fire. Too many unknowns here for me to tell you
much of what might be the problem. I assume of course, that the
circuit is wired up correctly. 

But here is my guess based on what I have been able to glean from
your post. Do you have any burns across your gaps? If the material
supporting a gap burns it conducts like a large, EXTREMELY LOSSY
RESISTOR. You would notice that the regular spark gaps were weak and
purple or red instead of the usual hot white. Or them may be white,
but wimpier than usual. Look for any burning or charring of wood or
plastic, especially at the spark gaps. If there is any of this burn
resistance, then the rest of the spark gap system would actually be
firing EARLY, but with a very low current. In other words, the system
would be sapping itself of energy in a sort of slow fizzle prior to
what would have been the big bang (had there been enough energy
left). My gut reaction is that something like this must be going on
in your system. Remember that conduction can take place INSIDE of an
insulator and you might not see it. Try to eliminate the major
variable by totally removing the series gaps. If the problem goes
away, then you probably have some burn resistance at work in the
series gaps. In that case, remove all metal parts from the series
gaps and re-build them.

> I thought maybe the RG213 high voltage feed lines to the coil maybe
shorting
> internally but I should see high primary current draw if that is
the case.  I
> have checked all the primary wiring probably a dozen times and
can't find a
> problem.  I am ready to take all the copper tubing back out and
rewire all
> the primary interconnects with wire again.  I have three static
gaps in
> series with the rotary gap.  The coil originally ran fine with
these in the
> circuit and I thought it would help quenching - should I pull them
out?  They
> are set at .030" each.
> 

Yeah, pull 'em out.... but for the reasons outlined above.

> After I shut the system down for the night, I checked the rotary
gap
> carefully and found the gap between the stainless steel acorn nuts
on the
> polycarb disc and the fixed (2) tungsten electrodes to be a bit
wider than I
> would like.  The disc doesn't run perfectly true so I need a bit
more gap
> than I would like.  The total was probably about .150 to .200".  I
closed it
> down as close as possible without it hitting.  The total gap now is
probably
> .100" plus the three .030 static gaps for maybe .190" total.  Will
the system
> be this sensitive to gap distance setting?
> 

Not on a rotary. The gap distance is a moving target in a rotary.
Such wobble in the spark system will not adversely affect the basic
operation, though it will affect the nature of the output spark a
trifle. Often makes for a more "interesting" output spark.

> Anyone have any ideas?
> 
> Thanks,  Ed Sonderman
> 
> 

Hope this helps or gives you some more ideas.
Fr. Tom McGahee