In .com (rec.radio.amateur.homebrew), Dave wrote:

What sort of plate caps were used? There are just pins, and
it looks almost as if there would have been a ceramic gizmo
like a tube socket to have bridged the two of them....

On the transmitter for the AN/ARC-3, the plate leads just had push-on
clips with a little bit of spring-loading, much like the contacts in a
tube socket.

--
You haven't lived until you've seen the households Great Hunter
Panther^wtomcat cowering in terror under a bush after being
caught in an instant thunderstorm on a sunny day.
-- Lionel, about his owner, in the Monastery