Re: Toob coil questions

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: dhmccauley-at-spacecatlighting-dot-com 

 >  > >16" is a LOT from a pair of 811As... the coil may be designed to drive
the
 >  > >tubes far beyond their ratings... You better watch that the pates DO
NOT
 >  > >get even a bit of color on them.  If they turn red at all, you are
pushing
 >  > >things hard!

Although this seems to be the trend among some of the coilers here, the 811A
and in particular the 833As can be reliable run bright red continuously.
In one of our legacy transmitters at work, we have large arrays of 833A (not
833C) vacuum tube.  I was very surprised to see that all of these tubes were
glowing
bright red on the plates.  The technicians there assured me the running the
833As red hot was normal and that the 833As were meant to take that abuse.
In fact, he
said the most common failure among the tubes was not any internal damage to
the plates or filament from these power levels, but the actual glass
actually melts and implodes
on itself.  He showed me a few examples of this and i couldn't believe a
tube could actually go through that type of deformation.

Dan