[Techman]

I think you're absolutely right folks. I was thinking that these old valve voltmeters took all their supplies from the mains power supply. I've just opened up an old Heathkit one that I've had for many years and found a festering 'C' cell still lurking inside! I must have known about these batteries and just forgotten over the years - haven't seriously used one since the early 70s. I remember having one of those great big wooden case model 26 things made by Electronic Instruments Ltd. and I'm sure it didn't have any internal batteries. Unfortunately I can't check as regrettably it 'disappeared' during the last house move.

The 'tube' in the Nashton looks a little long for just one cell, but that could be just an illusion. It looks about the right diameter for a 'C' cell, so I'll have to try one (or two) and see. I suppose I ought to remove that cell from the Heathkit now I've found it, as I happened to find a festering grid bias type battery in its multimeter brother a couple of months ago that had November 1970 penned on it and it had made a bit of a mess of the surrounding metalwork. The 'C' cell shown below in the Heathkit is likely to date from around the same time and would probably be the last time they were properly being used.