On Sun, 28 Sep 2003 16:26:34 -0400, John N. Power wrote:

> > From:         Jinx[SMTP:joecolquitt@CLEAR.NET.NZ]
> > Just out of interest, there's an explanation of why valve
> > heaters came to use 6.3V in the 9/2003 issue of Silicon
> > Chip. According to Vintage Radio columnist Rodney
> > Chambers (VK3UG), in the early 1930s valves had various
> > heater voltages but it was the efforts in the US to make a
> > practical car radio that led to the standardisation of valves
> > to run on the car's 6V (used at that time, and as you say,
> > actually 6.3V) battery
>
> That's right, although storage batteries were also used
> outside of cars for experimenters at home. To match the tubes,
> transformers were made in 6.3 (and 12.6) VAC.

Not just experimenters - don't forget that in the early 20th century not everyone had mains electricity.
Early radios (called "wireless sets" of course :-) had lead/acid accumulators for the heaters and grid
voltages, and "HT batteries" - 90V zinc/carbon batteries, for the anodes.  My grandfather had a radio shop in
London in the 1920s and one of the services they provided was recharging radio accumulators for their
customers!  Up until a few months ago I had some 20v (grid voltage?) lead/acid batteries from that era that
had never been used - little wooden rack holding a glass case forming the cells, two thick (5mm) lead plates
in each cell.  I finally decided that it was time to clear out a load of old stuff, and they went.  I hope
they weren't collectable!

Cheers,

Howard Winter
St.Albans, England

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