Large filament transformer 6.3V 168A

[DashApple]

Id love the see the cathode in a directly heated triode that needs 14V @ 450A xD

 

[Benm]

Oh there are much bigger transmitting tubes than the 4cx25k. How about this: http://www.e2v.com/resources/account/download-datasheet/191

There definitely are, at least up to a megawatt from a single tube. The 25/35 kW point is about the end of forced air cooled tubes, but water cooled ones go far beyond that power level.

Most tubes at such power levels require filament drive voltages larger than 6.3 volts though, as it's just not practical to deliver that amount of power at that low a voltage.

I've never seen the filaments on such powerful tubes, i reckon they are something like the filament in a kilowatt-power 12V halogen lamp and possibly more beefy than that. Cooling the anode is more of a challenge though, that gets a pretty decent bombardment of -very- angry electroncs during normal operation

 

[WizardG]

"i reckon they are something like the filament in a kilowatt-power 12V halogen lamp"

Something very much like that but with many of them in parallel.

 

[Benm]

Come to think of it, they once made electrical space heaters that had large coils of wire in them that glowed a dull red (bit like what you find in a bread toaster, but a lot larger).

I haven't seen a heater of that type in ages, but i guess they are still used in some places despite being quite dangerous.