Grounding problem

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Esondrmn@xxxxxxx 

I had some guests over the other night and was asked to fire up the 
Tesla coil for them.  This is only a 3" diameter coil with a 15 kv 60 
ma power supply but does put on quite a show.  I was running it in 
the same configuration that has evolved over many hours of testing 
and tuning which always worked just fine - but it wouldn't run worth 
a crap.  At one half power or less, I was getting intense sparks 
between the outer primary turn and the strike rail which only got 
more intense and more frequent as I turned up the power - to the 
point where I had to shut it down.  Also was getting some racing 
sparks on the secondary and the safety gaps were firing.  It was like 
the primary would ring up but I could not get the power out of it - 
like the coil was out of tune.  I knew tuning was not the problem and 
assumed that a connection had come loose somewhere.  Definitely 
disappointing - with an audience.

I worked on it today, measured the caps, checked all the connections, 
gaps, etc.  Everything was just fine.  It has been very cold here for 
a few weeks with most days not over freezing and down to maybe 15 
degrees at night.  I suspected that I might have a ground problem so 
I cleaned the outside connections and slowly poured about four 
gallons of hot water over the ground rods.  The coil now works 
fine.  Frozen, hard as a rock, dirt makes a poor ground.

When I used to run my large coil out in the driveway at about 7 kva, 
I would always soak the ground plane area for a while first.  I have 
never experienced a ground problem with my small coil like 
this.  Just goes to show - always run a demo for yourself a few hours 
before the guests show up.

Ed Sonderman