An inrush current limiter
in series with the filament only costs a dollar or two and can easily pay
for itself a hundred times over.

Hang on here. Do you know what 813s cost these days? Still only around $10
!!
I got two at a hamfest last week. Got them hooked up to a filament xfmr,
and let them cook for an hour. Boy are they sure beautiful sitting there
glowing in the dark. They seem to be saying to me, "Hey we've been waiting
for 60 years to get a chance to make some RF!"
I also have 2kv waiting. So next step is to jury rig them up and see if
they draw plate current, with a little bias control, before I commit to
putting them in a new homebrew amp.
Since I just finished an 8877 amp this winter I am a little cautious and
aprehensive about hamfest tubes, because when I first fired up the 8877 with
4kv I got just that - fire. Seems the "I think it is good" tube a guy gave
me actually had a grid-plate short. Took a couple weeks to clean up THAT
mess. Fun stuff.
Thanks for all the replies, OTs.

73

Rick K2XT