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

Joseph2k wrote...
>
> Jim Thompson wrote:
>
>> It's been a lo-o-o-ong time since I've lurked around a TV repair shop.
>> Wonder how fast HV regulator tubes like 6BD4/6BK4 can be pushed?
>>
> i have been digging around and they can handle about 20 to 25 mA continuous
> and about 200 mA peak 1% duty cycle and gave up on them as a poor target.

Looking at the curves, I'm amazed they can go that high, is that with
a positive grid and a high plate voltage?

> But that set me off onto power tetrodes from Eimac. Easy to get serious
> overkill but they are available and you could probably drive them grounded
> grid from a single 1kV 3A FET. Assuming relatively clean triangular pulses
> the power dissipation in the FET won't be too bad. And a 4CX35000 can
> certainly do its part; 20 kV anode / plate, 6A, PD 35000W (used in VHF
> transmitters to 110 MHz and 195 kW).

> Last problem is that output mode is still current rather than voltage,
> and i don't know how important getting a voltage ramp is.

We need a -3kV to -13kV voltage ramp, but a good way to get that is
a constant sink current into the node capacitance. For example, if
the capacitance is 100pF we need 1A for 1us. I checked the 4CX35000.
Whoa! It's huge, 50# and 17" high by 10" dia, and needs 300W in the
filament, sheesh! http://www.geocities.com/aaron_white/mwtube.html

> I don't recall what the intended repetition rate is but IIRC it as
> about 1 PPS? This setup could go 1000 times faster (save test time?)

We're still evaluating the cycle time.


--
Thanks,
- Win
.

Relevant Pages

  • Re: Wins next 10kV project, a 1us ramp
    ... Jim Thompson wrote: ... But that set me off onto power tetrodes from Eimac. ... the power dissipation in the FET won't be too bad. ... voltage ramp is. ...
    (sci.electronics.design)
  • Re: Wins next 10kV project, a 1us ramp
    ... > a positive grid and a high plate voltage? ... >> But that set me off onto power tetrodes from Eimac. ... >> the power dissipation in the FET won't be too bad. ... >> and i don't know how important getting a voltage ramp is. ...
    (sci.electronics.design)
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