John Robertson wrote:


Indeed, you need to know the tube value to be sure, but consider the
cost of batteries of the day and thus the B+ is likely 45VDC or thereabouts.

In those days some people made their own B+ batteries - way back when I
was a kid digging through attics in Toronto (mid 1960s) for old battery
sets I found a couple of home-made lead acid batteries that were glass
test tubes about 8 inches long mounted in a wooden box and there must
have been 15 to 20 in each case. Wish I still had them as they were
classic home-brew stuff which I always loved from the battery age of radio.



** The "battery age of (tube) radio" extended well into the 1960s.

Popular "portables" of that era used a pair of 45V packs for B+ and a large 1.5V dry cell for tube heaters - all made by "Eveready".

Miniature 7 pin tubes like the 1S4 and 1R5 were used - along with a transformer supply for home use with a multi-finned selenium rectifier.

https://www.radiomuseum.org/tubes/tube_1s4.html



...... Phil