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high-voltage limiter on bombarder, etc
Tom,
I too use that technique, having a pair of wires with an adjustable gap that
bridge the space across my bombarder trolley wires.. I still get some
flashback to the bombarder -- not much, and it goes away as soon as the tube
gets warm or if I drop the "closed stopcock technique" pressure a little bit
-- I like it mainly as an anti pop-through device. If I attempt to start
bombing at too high a pressure it'll pop across the wires instead, telling
me to drop down a torr or so... with the 30 kv on my secondary I keep the
gap about 2" or so.
My manifold is all metal, other than the section that connects to the tubes,
and so flashback is of great concern, both for my gauges and my arse. To
protect my gauges I have a grounding wire on an alligator clip, goes right
to the front clamp on the manifold, and I keep my pirani sensor on the far
end, behind a stainless-mesh type NW-KF screen. Six years like this and no
burned sensors from flashback.
To keep my arse from frying I don't open or close stopcocks while the tube
is lit --ever -- which is guaranteed by my having a *pair* of hand switches,
wired in series, such that both hands have to be on both switches in order
to energize the bombarder. (Theoretically I could still lean over and get
zapped in the face, but it hasn't come to that yet...). This wouldn't
really have been feasible back when I used a sliding-type choke, due to the
effort to pull it, but with an electronic choke I just turn the dial and go
back to bombing.
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Yah, I like "iron glass". If something's going in a crate (I do a lot of
interisland wholesale work) I like to anneal with a soft flame all sharp
bends... takes longer, but then, so does remaking it if the crate gets
dropped...
In Holland most of the neon goes through a full oven-annealling as part of
the phosphor bake-out process. That plus the way they bend (heating the
glass so much that it actually moves mass from the inside of the bend to the
outside, creating an even wall thickness) makes it, I'd say, the toughest in
the world....probably the most expensive too.
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I'd be curious to compare times on bombarding, open-stopcock vs. closed. I
used to do open-stopcock my first couple years in neon, then switched to
closed for several reasons -- mainly that we were using Neon Products
electrodes, and that's what they spec.
Regards,
Ted Pirsig