Stephens moved, Coronatron tests.
The advertised move to my new home and lab/workshop at Shelburne is now
finally completed! : ) Eager to get back to coiling I have prepared one of
the rooms in my new workshop building, this one 27' x 31' floor area,
to be my high voltage test room. The ceiling is only 10 ft, 4 inches at
the moment, restricting coiling to just small units but this ceiling
is at least sheet aluminum and grounded. As soon as possible I
propose to raise the ceiling height in this room to at least 22 feet.
This change and other instrumentation I am about to build will give
me commercial, high voltage RF test capabilities with which I hope to
secure a small yet lucrative niche in this very specialized marketplace.
I have just installed a good RF ground system and the shop building is metal clad.
I have also installed a dedicated 100 amp breaker to a commercial 4
pole, 90 amp, RFI line filter providing an isolated 230 volt, single phase power
feed which is accessible both in the firing room and outside, as is the
ground system, so that I am now ready to coil in a serious way.
Unfortunately, all my higher power disruptive coil work still has to
be done outside until I get my ceiling raised. Immediately outside a
roll up door in the test room is a spacious gravel parking lot
I've had some luck generating good high voltage with the Coronatron
in very early tests in the new lab. Lacking a dedicated secondary
resonator (not yet fabricated), just for initial testing I inserted the resonator from
my MTC system (50 inch close wound length of #18 AWG PVC covered stranded
copper wire on a 15.5 inch O.D. , 1/2 inch wall PVC form) into the tank coil until
the K was about 0.25. I found tune at about 118 kHz with adjusting the plate
tank tap to about 11 turns. I have a small 3 inch cross section by 18 inch
smooth commercial toroid on top and it breaks out at about 180 kV RMS
(measured). The blowtorch like flame that then comes off the toroid is about
8 inches long with an idlingly 2 kW plate supply input (2300 volts -at-
900 mA). Interestingly enough, the self excited power oscillator
employing three, 5 kW plate dissipation each transmitting triodes
rated at about 6 kV plate voltage *actually starts oscillating at Fo
(120 kHz)* when the plate supply is increased from zero to only plus 0.8 volts
DC! It _must_ be in tune! : )
This 8 inch plasma is quite differently behaved from that seen on the
toroid terminal of a disruptive discharge coil. It doesn't walk around like the
disrupter, just sits in one spot mostly until a gust of air comes along and moves
it. Then it will sit happily hissing from the new location. You can coax it to
move with a hand held ground wand.
At present this discharge detunes the oscillator so badly that by increasing input
power beyond about 2 kW it does not continue to increase in size.
It appears coming straight perpendicular out of the toroid
surface and for the first two inches it is a single white hot plasma arc channel
just like that you draw from a neon transformer. Then it goes blue,
violet and increases in a conical taper like a boquet of flowers
ending up in a hissing, writhing spray of violet mini streamers.
Corona starts to spray off the tip of a ground wand at about five
feet away! When the wand is 2.5 feet away from the upper part of the
secondary, just below the toroid I get St. Elmos fire a full 20 inches long
from the ground wand with no corona yet off the coil or toroid. If I
stand on an insulated platform about 4 feet from the device when
running at 2 kW and hold a metal wrench in my hand towards a similar
handheld wrench by someone standing on the floor farther from the
coil than I, we can draw a totally silent 2 inch white hot arc
between the wrenches, again just like the arc from a 15 K at 60 mA
neon tranny! Replace the gap between these handheld wrenches with a
40 watt incandescent lamp and the bulb lights up. If I place this
40 watt lamp in my mouth with my lips wetted and tongue pressing on
the lamp base inside my mouth for good contact, and then press the
bulb and my face towards the machine at a distance of several feet
the bulb will glow like a plasma ball. I gotta get a picture of
this! : ) This is all neat stuff that I could not do before with
the smaller 1 kW system because I didn't have nearly as much field
voltage. I expect to have even much more soon.
I cannot dial the thing up higher than 2 kW input because I start to get about 15
inch long streamers spraying off a sharp point located too close to the middle of
the big secondary coil where the oscillator power tube chassis is, which
lick the PVC wire insulation of the secondary coil, threatening to damage it.
I need to fabricate a rolled grounded metal surface to stop this breakdown
problem before I can proceed with higher power tests.
I've started work on my high voltage capacitive divider probe. I
really need it now. (see my post on field emission x-rays).
I _love_ the new place! : ) Boy, do I need lots'a steel shelving!
I am still at my old I.S.P. address, rwstephens-at-ptbo.igs-dot-net, but shall
soon be finding a local provider if possible, probably out of
Orangeville, the major center south of me about 15 miles. My new
address and phone are:
RR1 Shelburne, ON, L0N-1S5, Canada. Tel: 519-925-1771.
I'm physically located just a couple of miles west of Shelburne.
Direct correspondence, calls and visits from fellow coilers welcomed!
Knock knock, ring ring, spark spark ...are there any coilers in Ontario? (I know
of only five, and you know who you are). Let's get something happenin'
Robert W. Stephens