Re: New Testing
From: Chuck Curran[SMTP:ccurran-at-execpc-dot-com]
Sent: Thursday, September 11, 1997 6:20 PM
To: Tesla List
Subject: Re: New Testing
I believe my 8" x 28" secondary system and your present unit might be
very similar, so if it helps, I'll list how my system is set for
1.) 7 stationary vacuum gaps set at .025" and two rotary gaps at .025"
for a total of .225". Gaps start to fire at about 60-70% on the
pwerstat dial -- this setup has worked very well on both my coils.
2.) Welder has a parallel resistance of 13 ohms, in the form of two
2200 watt stove top elements.
3.) Primary current with no arcing on my 10 KVA pig is higher, if my
memory works tonight it might have been around 16-18 amps.
4.) My thoughts as I read your description jumped around a bit-- is
your pig really healthy? Might you verify it's output with a voltage
divider or a smaller input voltage. How was tune verified I have set
up my latest coil by checking resonance on the secondary and then
setting the primary to a point 5% lower for a rough tune starting point,
simply trying to stay aware of what the toroid will do to the secondary
resonace while running.
5.) I've never tried running with a couple of bigger gaps like you
described, I've always stuck with .025"--as long as the total is in the
ball park (.225") I would guess it should still arc.
6.) I use a circuit where the pig output feeds directly to the spark
gap and then the cap and the primary inductance in series, are in
parallel with the gap, pretty standard configuration. How is your
Not much to chew on here, but I hope some of the comparisons might be
of assistance--hope you find the bug. Sounds like a great ground
Tesla List wrote:
> 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.
> 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
> 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"
> 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.
> 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?
> Anyone have any ideas?
> Thanks, Ed Sonderman