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Another Tube story
Hello to all,
I have been working quite a bit on my tube coil. With much help from John
Freau, and the purchase of a very robust plate transformer from him, I am
getting some decent results. In my coil I am using two 833A tubes from a
recent purchases, they arrived in the mail only to have one filament bad,
but both have a single working filament (for those that don't know the 833
tube has two filaments in series). When I saw that only one filament was
good I was quite disappointed, but decided to use them anyway. To my
surprise, they worked quite well, but at first I treated them very harshly,
as I thought of them as "disposable". Now I wish I was more "gentle" with
them, as they are performing quite well. After much fiddling, I am now
getting a continuos 20 inch discharge to air and 4-5 strikes, per 10 second
period, to a grounded piece of Aluminum foil 23 inches above the discharge
point. I am inputting about 1500 to 1600 watts into the system. This coil
is essentially the same design as John Freau posted some time ago, the 20
inches with a MOT. This consists of a 3 inch diameter secondary wound 13
inches with #28 magnet wire, a 6 inch primary with 22 turns (I think) or so
(cylindrical) of 12 gauge PVC insulated wire, 0.0016 uFd poly caps for the
tank, and a voltage doubler using 3 uFd capacitance with my new "beefy"
diodes (series of 18 1KV -at- 6 Amp). This doubler is seeing 2890 volts from
the transformer. The transformer weighs in at 120 pounds, and is name plate
rated at 2.8 KVA, but can probably do twice that for reasonable periods.
Now all I need are some Kilowatt Tubes! Well, that and a 6 inch secondary.
The moral to this story is: Guys, don't toss those 833 tubes with one bad
filament! They may still have hours of joy left in them for the tube coiler.
Regards,
David Trimmell