What do you think on this GMI-11 tetrode?? http://www.gstube.com/catalog/?key=gmi11
B+ range from 1200 to 2000V, the glass botle is impressive strong to fly on Sukhoi SU-27 and MIG-29 radars.
A hi quality socket is cheap and plenty avaliable on Russian sites, different from the GM70 socket, which is expensive(Teflon) or unreliable.
Oxide cathode indirectly heated.
Heater voltaqe: range 23-28 Volts
Heater current: 1.75-2.00 Amps
Anode voltaqe: 1200-2000 Volts
Anode dissipation 350W CW & 500W SSB
2nd Grid voltaqe: 250-350 Volts
1st Grid cut-off voltaqe: -50 -70 Volts
1st Grid dissipation: 1.5 W
2nd Grid dissipation: 8 W
Capacitance Grounded Cathode connection:
Input: 55 pF
Output: 7.5 pF
Transfer: <1.0 pF
To start it seems easy than the 833A(2500 - 4000V) and the GMI-11 life expectancy is 25 years in radar or Ham Radio applications.
If its sound is good(Kinkless Tetrode etc) this tube may be a new 6C33...P.S.:
Also there is the exotic looking tetrodes GMI-83(metal plate) & GMI-83V(seems a gray graphite plate).http://www.gstube.com/catalog/?key=gmi83