Jan
there`s no any beam plates on GMI-83 or by type -83V , by GMI-83 it is just ordinary horizontally winded wires both for g1 and g2 grids , but by model GMI-83V grids wires are vertically parallel stacked forming wired cage around huge round cathode ,
btw, IMHO what`s important to notice is the fact that anode Pd-max is only 60W , so let`s say by B+=4000V and steady Ia=0,015A (15mA) anode will reach the limit of full anode metal plate disipation of 60W , (4000V x 0,015A = 60W) , so any anode current above constant 15mA will made thin anode plate to run red hot , which IMO is not good,
it is interesting by these types of pulse tetrode tubes that those mighty cathodes are capable to emit electrons pulse flow in amperes ranges , where anode plates are relative low power limited , but in the same time very unlimited for max. anode voltages which can be in range from 18KV up to 20KV.
there`s no any beam plates on GMI-83 or by type -83V , by GMI-83 it is just ordinary horizontally winded wires both for g1 and g2 grids , but by model GMI-83V grids wires are vertically parallel stacked forming wired cage around huge round cathode ,
btw, IMHO what`s important to notice is the fact that anode Pd-max is only 60W , so let`s say by B+=4000V and steady Ia=0,015A (15mA) anode will reach the limit of full anode metal plate disipation of 60W , (4000V x 0,015A = 60W) , so any anode current above constant 15mA will made thin anode plate to run red hot , which IMO is not good,
it is interesting by these types of pulse tetrode tubes that those mighty cathodes are capable to emit electrons pulse flow in amperes ranges , where anode plates are relative low power limited , but in the same time very unlimited for max. anode voltages which can be in range from 18KV up to 20KV.
Yes, they are clearly designed for low PRF pulse duty.
I think that is also the reason they need this high heater power, to support those high current pulses.
They are pretty specialised tubes apparently.
Jan
I have been looking a lot at headphone estat amps recently, and driving the cathode seems to be a thing with these, too. Why? Does this have to do with the estat principle somehow?
No nothing to do with estat as such. It is just a very simple way to turn a tube (whatever tube) in an almost-ideal pentode with its very high gain.
Assuming there is no grid current, Ik = Ia so you drive the K and have total control over Ia.
Tubes with G2 present an extra complication with Ig2, so (beam) triodes are best, hence my use of 6HS5.
Jan
Assuming there is no grid current, Ik = Ia so you drive the K and have total control over Ia.
Tubes with G2 present an extra complication with Ig2, so (beam) triodes are best, hence my use of 6HS5.
Jan
This has basic data of most Soviet-era tubes (see p.29 for 6E7P):
https://www.govinfo.gov/content/pkg...VPUB-C13-d2a05473e128fe2870dcfc0fa0c7a538.pdf
Jan
IMO Russian both 6P45S and 6P42S beam pentodes tubes can be also interesting choice for GG linear AB1 class operation , those tubes are very simmilar to European EL509/EL519 TV tubes , with max. anode disipation of 35W and max. anode peak voltage of 8KV for T-peak=18u-second , by these tubes is good that cathode are fully galavanically isolated from heater electrodes and also from all other electrodes which can simplify cathode driver circuit , but my rough calculation says that you will need four of these tubes per one push-pull ESL- OTL amplifier .
IMO Russian both 6P45S and 6P42S beam pentodes tubes can be also interesting choice for GG linear AB1 class operation , those tubes are very simmilar to European EL509/EL519 TV tubes , with max. anode disipation of 35W and max. anode peak voltage of 8KV for T-peak=18u-second , by these tubes is good that cathode are fully galavanically isolated from heater electrodes and also from all other electrodes which can simplify cathode driver circuit , but my rough calculation says that you will need four of these tubes per one push-pull ESL- OTL amplifier .
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Max anode voltage in audio frequency service is 2000. The 'smallest' tube reaching 6000 volts appears to be the 3cx2500a3 triode with a frugal 400 watt filament requirement.
The GP-5, 2mA is dc !!!, at 20kV, and without grid current . I cannot imagine this 2mA is a emission limitation . I would thinck at the much lower anode voltage you would use you can run up the anode current till you reach the power limitation of 40W or so. To do so, you need gridcurrent offcourse, just as with about any triode with extremely low "Durchgriff" it will need gridcurrent to be able to supply sufficient anode current, A2 operation is the way to go. No idea what power the grid can take or are there any other implications besides grid temperatur, but i thinck it is worth trying.
As to mpulse triodes, they are specially designed to cope with a certain amount of breakdowns and pulseduration is a keyfactor regarding theyr voltage capabilities., check out the pdf
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Jan, If i where you, I would just take one of those TV shunt stabilizer tubes to find out how suitable they would be for the task.
Build a fullwave voltage multiplier with some 400-550V CT transformer.
Hook up the tube with adjustable positive grid voltage, adjust necessay positive gridcurrent till max anode dissipation at the different high voltage steps you get from the multiplier.
DC link caps and avalanche diodes like the BYW96 are your friends.
The first cap of each halfway multiplier side could be taylored to limit the max short current .
Then one can safely climb up the ladder tubelabs style till the tube pops or sensible gridpower is exceeded.
I would thinck something up to 100mW on the grid is something just about any tube can take.
Build a fullwave voltage multiplier with some 400-550V CT transformer.
Hook up the tube with adjustable positive grid voltage, adjust necessay positive gridcurrent till max anode dissipation at the different high voltage steps you get from the multiplier.
DC link caps and avalanche diodes like the BYW96 are your friends.
The first cap of each halfway multiplier side could be taylored to limit the max short current .
Then one can safely climb up the ladder tubelabs style till the tube pops or sensible gridpower is exceeded.
I would thinck something up to 100mW on the grid is something just about any tube can take.
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