I was going to mention that, Michael, but did they do that on radios in the 30s? If they didn't use mains transformers they seem to have excelled on the 117V AC/DC radio.
TV, of course, is different but we're talking about well before the TV era here ...
When all else fails, read the instructions
Yes, many 1930s Midgets and most of the 1940s Midgets, because they only stopped TV Production in 1942 (But didn't shut down TV transmission), and WWII only started there on December 7, 1941. The remaining heater dropper (much smaller than here!) sometimes in a line cord, so really almost no "excess" heat in the "direct" AC Midgets. The lower mains is also why the 100mA series wasn't as popular with radio designers (as they liked to fit as many valves as possible), so they have lower voltage 150mA types rare here.
Some DC 117V sets though. The Doubler types of course are AC only though no transformer. Essentially a lot of valve car radios very similar HT to DC 117 Mains types, less stress on vibrator pack. My KB 6V table model is only about 120V HT. It uses same pair of valves for Mixer/Osc and IF as many KB UK mains models and uses a 1937 Car Radio o/p valve and 1940s car radio det/preamp valve, it's parallel heaters of course though.
There were rectifier valves produced to work as voltage doublers by the British manufacturers: the UD41 by Mazda was one such valve but it was usually a metal rectifier. IIRC the Bush SAC4 Bushranger was another set that used this configuration.
... There was a terrific vogue for voltage-doubling rectifiers in power supplies in the early 1930s, especially in conjunction with a metal rectifier ...
You learn something new every day!
Such sharing of knowledge is one of the joys of this forum ...
The strange thing is that with mains transformer technology so far advanced compared with the relatively new introduction of electrolytic capacitors, it is the last thing I would have expected to happen!
(I did go back through the few 1930s PYE service sheets in the library before my earlier post but they all show a full wave valve rectifier ...)
You need to get back to the era of the "Rising Sun" sets such as the MM, P/AC, E/AC and the like - all these use the doubler configuration.
Loads of these in early 30s
http://www.radiomuseum.org/tubes/tube_cy2.html
Often paralleled for more current on 200V to 250V sets.
If substituting a full wave rectifier, always be suspicious of the idea of rewiring a dual cathode dual rectifier, they are usually for doublers and can't take PIV of full wave transformer (twice direct off 250V mains).
