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Re: The New Guy
Original poster: FutureT@xxxxxxx
In a message dated 1/17/07 8:30:11 PM Eastern Standard Time,
Original poster: Dan Williams <coilerdude@xxxxxxxxx>
Hello, I am both new to this list and to coiling. I am 40 years old
and have wanted to build a coil for 20 years +. Just built my first
disruptive coil using a 10/23 OBIT, getting 12" strikes so-far.
Have the bug BAD! Need caps, if anyone can give me suggestions on
where I can scrounge some LARGE caps for another project or has a
diagram for a VTTC using an 813 tube please let me know.
Welcome to the list and to coiling. Any coil designed for an
833A can use an 813 tube instead. You'll need to perhaps
adjust the grid feedback and the grid leak resistor. You can
either tie the both grids together, or supply the screen grid
from a dropping resistor from the power supply transformer.
In one experiment I took a VTTC which I designed for an
833A, and installed the 813 tube instead. It gave the same
spark length of 19 or 20 inches after making some adjustments.
In general if the grids are tied together, then fewer turns are
needed on the grid coil, because the tube behaves more as
a zero-cutoff type tube. I guess I supplied about 4200 volts
to the 813, so apparently it can handle that voltage. An 833A
can give longer sparks than 20" if you supply enough plate
voltage. The graphite plate of the 813 will eventually heat up
red hot in radical VTTC usage. I've heard that this is "bad"
(heating graphite plates to red-hot) although I don't worry about it.
I devised a method that I call the "staccato" mode of operation
which runs the tube in a pulsed mode so it runs cooler and
gives an interesting sound and visual effect.