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Re: New testing, more


From: 	Scott Myers[SMTP:scotty-at-wesnet-dot-com]
Reply To: 	scotty-at-wesnet-dot-com
Sent: 	Friday, September 12, 1997 7:26 AM
To: 	Tesla List
Subject: 	Re: New testing, more

Tesla List wrote:

> From:   Esondrmn-at-aol-dot-com[SMTP:Esondrmn-at-aol-dot-com]
> Sent:   Thursday, September 11, 1997 7:10 AM
> To:     tesla-at-pupman-dot-com
> Subject:        New testing, more
>
> 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
> not.
>
> 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.
>
> 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?
>
> Now I am answering my own post.  This exact set up has now killed two
> C.P.
> caps.  I can't afford to keep doing this.  Maybe you can have the
> resistance
> of the primary circuit too low and the cap can't take it.  By the way,
> the
> primary is 14 turns of 3/8" copper tubing for a total of 84
> microheneries.
>
> Thanks,  Ed Sonderman

 Hi Ed,

OUCH!  Sorry to hear that.  It can be VERY expensive indeed.

If I had to guess on your system, it sounds like you have excessive gap
distance or undervoltage from the pole transformer.  I have had this
same erratic spark behavior myself and found it was too much gap
distance.  If you get a new cap, try getting them rotary gaps as close
as possible and taking the series static gaps out of the loop.

Regardless of the tune of the tank circuit, the gaps should fire when
the capacitor is charged.  And the capacitor safety gap fires first???
Not good.  This takes me back to the excessive gap theory.

Good luck on figuring this one out,
Scotty