Keep your voltage to frequency ratio constant

I remember reading W1FB's review of the Yaesu FT-301d radio in the October 1977 issue of QST.  Particularly this:

I also remember Professor Gustav Staats at UWM telling us:  "keep your voltage to frequency ratio constant".  In other words when in Barbados or Japan or other places with 50 Hz AC power you want a nominal 100 volts input to a transformer rather than the 117 or now 120 volts here in the US.  OR if you don't, be prepared for major problems !  Honestly I don't remember the exact reasons why but that phrase has stuck with me over all these years.  But I know that it is related to the observation that the higher the frequency, the less mass is required in a transformer.  Witness the use of 400 Hz to power WWII era surplus aviation radio gear.  Anyway W1FB didn't mention the AC voltage in Barbados but I suspect it was higher than 100 volts.

This isn't a problem with switching supplies since step 1 in any switcher is to rectify the AC.  The switcher then uses a relatively higher frequency (than AC) oscillator to drive a small, usually toroidal transformer.

Best Regards,
Chuck, WB9KZY
http://wb9kzy.com/ham.htm