weird-duck British tube, this one is a multiple-voltage regulator... a
gas shunt regulator tube that provides regulated voltages of 280, 210,
140 and 70 volts DC at 40 ma, thus making it useful for preamp/driver
circuit projects or circuits that need multiple regulated bias voltages.
Very cool looking in operation, too!
Nice 1960's vintage genuine Marconi British made STV280/40 CV1068 Stabilovolt tubes. For more information, see : http://www.mif.pg.gda.pl/homepages/frank/sheets/126/s/STV280-40.pdf
These tubes use a B4 British 4 pin socket, if you need sockets to go with thse tubes please see socket section.