I just found several 829B tubes - believe it or not in my garage - I
must have got them in a box of stuff at a ham fest at one time.
A check on Ebay shows they're pretty much worthless for the sake
of dollars, but they're so COOL! With the two plate caps that are
actually just stiff pins, they look like little Martians.

I put a pair on my office credenza just to look geeky cool. Fresh
out of the box as NOS they look amazing - just like they were made
yesterday. It's a pity they have no value - maybe as a homebrew
project??

So can someone tell me what they would have been used for?
Something tells me they're a VHF power tube.

They are about the same as a pair of 6146 tubes in one envelope but are more
efficient at higher frequencies.
Good for about 100 watts out at 2 meters and somewhat ueuable at 440 mhz.
I think the old VHV book had an amp in it for 144 mhz that was rated for
about 40 watts out on AM and more on CW/SSB.