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Re: Other changes
Tesla List wrote:
>
> >From Esondrmn-at-aol-dot-comFri Sep 13 22:55:03 1996
> Date: Fri, 13 Sep 1996 14:44:55 -0400
> From: Esondrmn-at-aol-dot-com
> To: tesla-at-poodle.pupman-dot-com
> Subject: Other changes
>
> Jim recently asked me if I made any other changes to my system other than in
> the primary which may be related to my recent problems. I said no but last
> night I realized that it was at the same time that I completely rebuilt the
> main RF ground. I drove in three 8 ft copper rods in a triangle with 8 foot
> legs. Then I connected all three together with galvanized roof flashing and
> then soldered the flashing to the ground rods. Then I covered the whole
> thing with about 100 lbs of rock salt. The connection from the ground system
> to the coil was also changed to use 6" wide flashing about 5 feet total to
> the bottom of the secondary. The old system used three 8 ft rods driven in
> about four feet apart, connected together with #6 twisted bare copper house
> ground wire and connected to the coil with about 20 feet of the same wire.
>
> The coil now should see a much better ground. Can this be the cause of all
> my primary and AC feed problems???
>
> Ed Sonderman
Ed,
Not Likely. The grounding system would influence coil behavior AFTER the
gaps fired, but should have no influence on the initial breakdown
voltage of the gaps. [A note: over the long term you may want to
re-verify the integrity of your ground since the salt solution may
attack the galvanized steel due to the shorted battery (galvanic
corrosion) formed by the copper groundrod and the flashing.]
Does your welder start growling when your gaps are NOT firing, and does
it seem to rather abrubtly increase in volume as you slowly increase the
variac setting? What is minimum gap length of your static and rotary
gaps respectively? If your gaps begin sporadically firing at relatively
low settings, and you hear growling at relatively low voltage settings
you may be resonating your tank cap/ballast. This condition can make the
coil run VERY well while in 60 Hz resonance, and significantly less so
when you increase/decrease ballast inductance and drive the system out
of the peak.
Recent changes you've made to the system (especially removing the
ballast resistors) increase the 60 Hz Q of the system, making the region
of 60 Hz resonance significantly narrower but much "hotter" when you hit
it. Although Tank/Ballast resonance can make a coil run VERY well (even
"synergistically" so...), it CAN over-stress a tank cap particularly
when used with a rotary gap. The peak cap voltage will rise to QxVout
unless the cap shorts or the primary gaps or safety gap clamp it to a
lower (nondestructive) value. With no resistors across your ballast
inductor, your 60 Hz Q may be quite high. This may take out your cap if
your rotary misfires...
Try measuring the pig input voltage with a CHEAP multimeter. Do you see
any differences in voltage for a given variac setting when the coil is
working versus when its not? Do you see any sudden increases? By taking
and recording a number of strategic measurements and noting any other
behavioral differences between when the coil is working properly and
when its not, we should be able to get to the bottom of this!
Safe (but intermittent) coilin' to ya! :?)
-- Bert --