Re: 4-125A, vacuum tube do's and donts

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 4/8/02 4:08:33 AM Eastern Daylight Time, tesla-at-pupman-dot-com
writes:

Matt,

You are wise to ask this question, since tubes are susceptible to
destruction in various ways.  First of all, never let the filament
voltage go more than 5% over the rated voltage.  Never let the
plate get too orange-red.  An orange red color is normal, but
you don't want it to get orange or yellow.  A good way to run
the 4-125A's is to tie the both grids together and run them as
a triode.  Circuit values have to be correct for that.  Use a
plate lead choke/resistor to prevent tube damage in the event
of an internal arc-over.  This tube can acually withstand a higher
plate voltage of 4kVAC or so.  All the adjustments are critical
for best results in a VTTC.  This tube can give a 12" spark or so.
Run the tube only in an upright position.  If the tube gets very
orange, but the spark output is weak, then things are not adjusted
correctly.

cheer,ss
John

>
> Hi all,
> I have gotten my 2 4-125As and am about ready to begin my first VTTC!I dont 
> know much about vacuum tubes so I want to ask yall what are the things NOT to
>
> do to a vacuum tube that maybe yall have done while experimenting.I know my 
> tubes can handle 125watts apiece and 3kv plate voltage.
>
> Just what are the key thingsNEVER to do to a tube.(aside from the obvious 
> smashing,dropping ect.)
>
> Thanks,
> Matt
>
>