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Re: [TCML] Control Cabinet, X-ray cable, RF-Mains grounding

Hi David,
Yes, you turned my on to the pig ear ground several years ago. The reason I like this configuration has "nothing" to do with primary strikes (as mentioned in your 1st paragraph). That will happen with or without this wiring technique from time to time. The reason I use this wiring technique is for two very simple reasons: 1) to keep the inner turn of the primary and bottom of the secondary at the same (minimum) potential to each other. 
2) to simplify hv wiring out to the coil.
The excessive primary strikes would have still occurred with either the floating or grounded connection. Considering the top load potential versus the potential at the outer turn of the primary, there would be little difference. The strike ring however may pull strikes toward the primary at times, but I believe pretty strongly this situation is power dependent along with terminal height and size. I think in many cases, the strike ring may help the bad from happening, but sometimes it may be counter productive and actually hurt the situation. Apparently, the strike ring didn't help much with the Hipotronics Pulse caps. I suspect the strike ring was targeted by the terminal breakout and the primary also was hit in the process. But, without the strike ring, the primary can still be hit and do the same damage.
If your getting a lot of primary strikes, than there is always cap risk. The idea of removing the strike ring is to attempt to reduce the downward primary strikes. It doesn't prevent them. My personal view is that if a coil has enough power to not quite get to the ground but plenty of power to hit the primary, then the primary will be hit often. This might a coil that needs a strike ring. Although you may get more hits on average down there, many of those hits will be directed away (some will still find the primary and cap). But on systems that can't reach the primary or coils that can easily hit the ground, your probably better off without a strike ring (on average).
I don't believe in a global "lose the strike ring" epic, or "use the strike ring" epic. I think each coil has to be evaluated (and maybe tested) to determine if there is or is not a benefit. 

Take care,
Bart

David Rieben wrote:

Hi Bart, Jim,

If I'm not mistaken, I was the one who originally turned you on
to the grounding one of the ears of the pig to allow a single HV
transmission line from the pig to the primary circuit ;^) However,
after some recent discussion with one or two members, I am be-
ginning to wonder if this is the best configuration in light of suppres-
sing primary coil strikes. I have been running my Green Monster in
this fashion but have noticed rather excessive primary strikes. As a
matter of fact, I smoked my beloved Hipotronics pulse cap during
a recent firing of the beast for a mini-Teslathon ;^( (3 of us). I'm
not sure but it was mentioned that a large primary strike was seen
right before the Hipotronics caps gave up the ghost. Of course I
have an RF grounded strike shield ring and I was figuring that this
may be the main culprit for primary bound strikes. Do you guys think
that leaving the primary coil "floating" with not connection to RF
(mains ground) will suppress primary bound strikes from the
topload or is this a sure recipe for distruction of the primary circuit
components? Of course, I realize that one of the best methods of
suppressing primary strikes is to add an extra corona shield toroid
underneath the main topload. I have not done this in my design main-
ly due to the shear size of my main topload (12x56") in comparison
to the outer diameter of my primary spiral (about 40"). It seems to
me though that the RF grounded strike ring (which is about the same
diameter as the outermost primary turn - ~40", and sits on a horizon-
tal plane about 4" above the primary coil's plane, is the main culprit
at drawing the strikes toward the primary coil, regardless of whether
the primary coil is "floating" or grounded. What do you think?

Fortunately, I had a spare Plastic Capacitors BNZ custom made pulse
cap that I got as a spare from list member Bill Limeaux (Gomez
Addams), that was of the same capacitance as the now defunct Hipo-
tronics cap (.1 uFd) that I was able to swap out to get the Monster
breathing fire again ;^)

Anyway, sorry for the rather lengthy post but I am really curious
about this issue and thank you all in advance for your responses.

David Rieben

PS - I, too, have been tying the external tank of my pig to RF
ground via the transmission line from the tank circuit assembly
and if I disconnect the primary coil from the RF ground, then
the pig's external tank will also be floating (that just doesn't
sound good to me!)


----- Original Message ----- From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, December 16, 2008 8:08 PM
Subject: Re: [TCML] Control Cabinet, X-ray cable, RF-Mains grounding



Hi Jim,

Jim Mora wrote:
I know that the spark gap ends need to be stripped back to the PE for 12 to 
18". I am on the fence how to best and safely make this connection. Dr.
Resonance suggests grounding one side of the PT and using his RL filter and 
thusly one HV feed. The perceived downside of this is that RF and mains
grounds are tied together albeit through the air core and resistor bank.
I ground one ear of my pig to RF ground as well as the case, thus, a single hv feed to the coil. Mains ground stops at the control cabinet. In this configuration, there's no connection to RF and mains ground (filter or not). 

Bart
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