It's been a LONG time since I did any vacuum-tube work, but the Air Force did spend a lot of time and money training me how to do it! As I remember, the vibrator is used to create a pulsating voltage that can be run through a transformer, and stepped up to a high enough voltage to be used as the B+ voltage on the tubes. It won't matter what polarity the low voltage is, as long as a mechanical vibrator is used. Solid-state oscillators do need correct-polarity voltage, but most of them are 12 volts, I believe.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!