If you are firing up the tube for the first time in many years, let it bake
with full filament voltage for a few hours to allow the vacuum to stabilize
and degas.

After the initial baking session from then on a second after filament
voltage is applied, you can apply all voltages for transmit.

Chuck...K1KW


"Rick" wrote in message
...
How long after applying filament voltage till the 813 is ready to
transmit?
Is it like a 3-500 or do I have to wait 30 seconds or so?

Rick K2XT