If so, when working with a load that involves voltages > 1kV and power levels well into the kilowatt range, which type of tube would be more useful: Triodes or Thyratrons? I saw a similar question about the possibility of using thyristors for an h-bridge control circuit. Could thyratrons be used as well?
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1\$\begingroup\$ Which has the lowest turn on impedance is the thing you should look for, as well as voltage withstand and switching losses. So what do you think if you read a few data sheets on various devices? \$\endgroup\$– Andy akaCommented Mar 10, 2017 at 20:46
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2\$\begingroup\$ Never seen a vacuum tube bridge. (But I can't rule out something of the sort with mercury rectifiers in railway motor drive systems). Vacuum tube circuits tend to use different topologies, thanks to the cost of a vacuum tube versus a passive component like a transformer. For example, rather than bridges, they would use two low-side devices and a transformer with a centre tapped primary. This is the classic "push pull" amplifier of the 1930s onwards. Much simpler topology and avoids high side drive problems. \$\endgroup\$– user16324Commented Mar 10, 2017 at 21:09
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\$\begingroup\$ Hey Brian, wouldn't pentodes work better for electronic switching(at low frequencies and DC) than thyratrons because the trouble with thyratrons is the grid loses control once the arc is initiated so they need a separate "extinction circuit" to shut them off. \$\endgroup\$– Mr XCommented Mar 13, 2017 at 3:31
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Mercury Arc devices were often manufactured in multiple anode packages so center tap schemes make sense .Vacuum tubes can and do have very high Anode voltage ratings but the Cathode filament voltage rating of a indirectly heated tube is low .The directly heated tube has a heater cathode voltage rating of zero because the heater is the cathode .Directly heated tubes are more common at high power. Filament power requirements are lower for directly heated tubes .This means that if you did a vacuum tube full bridge at high power which means high voltage you would have to isolate the heaters .Such heater isolation would be a penalty if say you were dealing with thousands of volts of RF on say a 50Kw AM transmitter.The full bridge produces twice the power as the push pull with twice the number of vacuum tubes .The total cost including skilled hand assembly of a 4 valve full bridge will be more than a 2 valve push pull that used larger valves to make the same power .
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\$\begingroup\$ The reason I asked about the h-bridge topology is that it can be used for PWM. \$\endgroup\$– Mr XCommented Oct 24, 2019 at 4:13