|Capable of handling voltages of up to 40 kV,
this tube is a real high-voltage rectifier. And it can handle considerable
currents, too: up to 100 mA, peak current being much higher - about 1 A (the
resulting peak power being 40,000 Watts!). Needless to
say, that at these extreme voltages, it needs a perfect high vacuum for
sufficient internal insulation without the slightest traces of gas. So, the cathode
is a simple direct heated pure tungsten filament rated at 5 V, 6.5 A. The
plate is made of a hard-metal with external high-temperature getter coating
(the grey center region), like in transmitting tubes.
Some cooling of the top anode cap should be recommended, since this tube has a quite high voltage drop of a few hundred Volts. And with maximum current, a considerable plate dissipation will be released - up to 100 Watts.
All pure-tungsten filaments should be heated only as much as is needed to reach sufficient
emission (contrary to all other cathode types, especially thoriated ones, which are the most
sensitive to over- and underheating). Even reduction of heater voltage by a
few percent will increase tube (filament) life two- or threefold.
So if you're experimenting with such devices - be careful and take appropriate shielding measures! Needless to say, that these high tensions are absolutely lethal.