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On 2/13/23 5:39 PM, pupman.com@xxxxxxxxxxxxxxxxxxx wrote:
That's a cheap jab at an article from over 2 decades ago.
MMCs are just as retarded as a string of cheap, available diodes when
you can just get better capacitors.
Having recently looked for capacitors, MMCs are still the most cost
effective way to get the 20kV kinds of voltage and capacitance you want,
if you're not going to be hunting surplus. There's just not much of a
market for 20kV 0.01 uF capacitors that can take the high di/dt and
currents. Transmitting ceramics are a possibility, but 10,000 pF is
"big". You can get a VIshay 714C30DKD25 at $54 - you'd need 4 of them
in parallel. ANd I'm not sure those can take the current - They are
rated at 0.02 dissipation factor at 1kHz, but that goes up a lot at
100-300 kHz. A HT571500-15 is 15kV, 1500 pF, and is $59 (but rated for
5Amps). To get close to 0.01uF you'd need 6 of them, which is $360.
10 caps at $7 each is $70. That's a whole lot cheaper than buying the
equivalent from Maxwell (or whatever they're now called)
If you're building a *larger* coil (> kilowatts) and you're only
building one or two, then hunting the surplus might turn something up.
There are all kinds of deals of various transmitting capacitors that
turn up, but they're from sources that don't have a lot of track record,
or poorly documented. As opposed to buying the trusty 942s from CDE via
Mouser, Digikey, etc. You order them, they show up in a couple days,
you know what you have in your hand, and you know they aren't used, etc.
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