🚀 go-pugleaf

Built a couple of triodes for my 8-th grade science project
back in the 60's. I sort of cheated and used the filament
from a busted 5U4GB (rectifier) tube, but used a piece of
window screen for the grid.  The grid & plate were attached to
a movable assembly (alligator clips), so they could be moved
around and the characteristics observed.  One would have to take
the tube apart to do this.. Had a 2 stage vac pump on loan from 
Earlham College then to pump it down.  Vessel was a "Gerber"
baby food jar.  The lid was the plate connection & vac connection,
grid + fil came thru holes drilled in the bottom, sealed with
epoxy (had just been invented back then). It seemed to work.
Was able to get voltage gains of 10X or so I recall in the
linear region.

Put a cricket in one once, and hit it with a neon sign xfmr (9KV, 30ma)
during the pumpdown.. all kinds of St Elmo's fire off the cricket's
legs and sharp edges.  Cricket was knocked out, but later revived
after the 3-4 min session.
--ghg