Special DuMont 109 maybe available?

[wa2ise]

Originally Posted by Tom Albrecht

Looking carefully at the circuit, I believe the "polarizing relay" is NOT a vibrator, but merely a relay which makes the set work regardless of which way you plug it into a DC outlet. Probably a relay with a permanent magnet that is sensitive to polarity of current in its solenoid.

Doing that would avoid the voltage drop you get with tube rectifiers, and hopefully gives enough protection to the electroytic caps against reverse polarity. If the relay is normally open with no power applied, then maybe only when it sees power it makes the correct connections without the caps ever seeing reverse polarity. Like a cross wired DPDT switch with center off.