[MrFixr55]

Hi Oldie,

The 250VDC is not so crazy an output. The power supplies for the vast majority of transformer powered tube radios from about 1932 to the last transformer powered tube radios had an output voltage of approximately 250V for B+. This is the reason for the output of the dynamotor. Some WWII military vehicles and most airplanes used 24VDC. "Command Sets" used dynamotors and many hams subbed a simple power supply for them.

I am not familiar with Northern Electric (the Canada equivalent of the USA Western Electric) sets but I have rebuilt 2 Northern Electric crank phones. Is this the typical AA5 Set (12SA7, 12SK7, 12SQ7, 50L6 and 35Z5? I have an Emerson 330 that was wired the same way. It may have been a war repair because the 50L6 was replaced by a Loctal 35A5 in an adaptor, or the set was built with a 35L6 before the 50L6 was introduced. Mine had a dropping resistor (likely added) so I switched to 50L6 and took out the resistor.

Unless your set has a voltage doubler rectifier, the output of a rectifier is a lot less than 160V. While 160V is the theoretical output of rectifying 120VAC RMS, the size of the filter caps and voltage drop across the tube comes into play. The actual output of a 35Z5 or 35W4 based AA5 power supply is closer to about 95-110V (if you are lucky). Philco made a range of radio-phonographs using a 50Y7 rectifier as a voltage doubler. this did, in fact produce about 180V, but only if the set was run on AC. The set was rated AC only due to this voltage doubler and due to the AC only induction motor in the record changer