Win's next 10kV project, a 1us ramp

Sure, but who wants to wind that on a toroid?

I'll have to test some small teflon coax just for fun. I have an old Spellman hv supply that goes to 30 KV.

John

Very pretty, except for the radiant heat peeling the stickers off the fans.

I think Win should do it with a big tube, just for the sheer novelty of it.

See abse for my 833A.

John

AWESOME!! I'd have to use three or four in series?

Aren't those those things where the FBI comes and arrests you?

Doesn't RG-8 have a really good HV rating?

For my 30KV stuff at MIT we used parallel-plate (aluminum) transmission lines with Teflon as the dielectric ;-)

...Jim Thompson

Perhaps that could work, as a fallback. I'll have to check.

How about a HY11 or similar hydrogen thyratron. ~20kV anode voltage,

Best regards, Spehro Pefhany

That's the other issue, will they even sell them to me? Do I need to re-instate my security clearance to see a datasheet?

I did a similar thing a few years ago, however softer specs. My approach was a stack of transformers driven in parallell by mosfet power transistors. The transformers were made of toroid ferrite cores. Wound by hand with about 300 (at secondary) turns each. What about doing it with ten of them and 500 turns each ;-) /Sven Wilhelmsson

I see a list of stuff at Perkin Elmer, but they make me request the data rather than simply download it... OK.

Where do you see the 100-200ns detail?

As I recall, the heater requirements are on par with a 12AX7, so the emission is on par. Same as 12AU7 yes, which is a bit beefier, so the electrons may just be hiding behind the grid; but still nothing anywhere near needed. You'll probably get the grid hot enough to boil electrons off, and still not have enough emission ;-)

Although... 10 or 20 in parallel might work. That's a lot of dead weight capacitance though, isn't it?

Tim

-- Deep Fryer: a very philosophical monk. Website:

The 6BK4? I have two NOS 6BK4C/6EL4A Westinghouse tubes on hand for $5.00 (US) each. they are available from a lot of surplus dealers, and the bunch over on news:.rec.antiques.radio+phono could probably fill a dump truck with them.

Thats exactly why I used a _stack_ of toroid ferrites. Each of them does not need internal HV-insulation, and toroids have low leakage inductance. The primary can be an insulated rod through all the toroids. Thats the HV-insulation. But, as indicated above, the cost of handwork can be high. /Sven

PE say full off to full on in 100-200ns

Best regards, Spehro Pefhany

In article , Winfield Hill wrote: [....]

ASCII Art:

pivot 0================0===============0 ! # ! Copper plate ================ ### ! ! ! ! ! Piston Gap ### ! ======= ! assembly Copper plate ================ ### ===== ===== Non conductive ! ! ### ! ! mounting ! ! ### X-X Steam valve . ......### / \\ . . ### ! ! Boiler . . ### ------- . . Conductive . . mounting . . . . cam operated . . Lead wires switch ! . GND --- . 3KV -----O O-----+--------------- To load

Or, perhaps:

Some ceramic capacitors have decreasing capacitance for increasing voltage. You may be able to use these to straighten out an RC ramp reducing the problem to just one of switching.

Closed it.. let's see (click click) ah, here:

Page 2. Note the nasty 100ns commutation spike wot comes out the grid.

Best regards, Spehro Pefhany

I was thinking a custom design. You're not suggesting a TV flyback are you? Way too slow I'd think.

OK, I had that (it's all you can get), but didn't read it carefully enough.

"During commutation, a high voltage spike appears at the grid of the thyratron. This spike happens in the time it takes for the plasma in the grid-anode space to "connect" to the plasma in the gridcathode space. During this time, the anode is momentarily "connected" to the grid thereby causing the grid to assume a voltage nearly that of the anode?s."

Ouch!!

Hello Michael,

I just don't know whether they could do the pulse current in Win's application. You could probably extrapolate and drive them a little into the grid current region but there comes a point where particles may be ripped off the cathode.

Regards, Joerg