Avery Fineman wrote:

A slight advantage of vacuum tubes in capacitor-input rectifier
circuits was that the very high initial turn-on surge isn't there;
a vacuum tube diode literally turns on slowly as the filament
warms up. In cheaper tube designs that was offset by the
higher heat dissipation of tube rectifiers creating a local hot
spot much higher than with semiconductor rectifier diodes.
[typical heat dissipation of a 5Y3 common dual-diode in 100
Watt units was 15 to 20 Watts all by itself]

I seem to remember the 5Y3 as directly heated which means it warms up
before the rest of the valves in the set so producing high HT value
intitially. Need to take this into account with electrolytics.

Peter

Len Anderson
retired (from regular hours) electronic engineer person