"Michael A. Terrell" wrote in message
...

The water cooled 25 KW finals used in the RCA TTU-25 series used
optically aligned elements, and no one ever managed to get more than 50%
output out of a rebuilt tube which is sad, because RCA designed it to be
rebuilt. The bottom of the tube had a removable cover to get inside the
tube, through the water jacket. Most attempts at rebuilding were so bad
that you couldn't even use the tube in the aural cabinet for 12 KW. The
tube used a pair of 1000 A, 1.5 VAC heaters.


Was there a mechanical alignment issue? The tubes I spoke of were only
pumping 5KW but the four of them were glowing cherry red. The transmitter
was only off after the station cut over to the standby transmitter about
once
a month.