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