E640 is Neda #1105, Burgess Hg-640. It's a 1.4 volt mercury battery. 5/8" dia x 7/16. In 1970 they were selling for 15 cents each.
These are very small batteries. You should be able to find watch or calculator batteries around this size. Mercury batteries are no longer available.
Norm
:HELLO IM GEORGE,,, AND I HAVE A PROBLEM ,,,(PLEASE HELP )ME IF YOU CAN MY FATHER HADS A COUPLE OF THESE RADIOS THAT HE USED TO LISTEN TO IN HIS YOUNGER YEARS NOW THAT HE PAST AWAY ILL LIKE TO KEEP THEM AND LISTEN TO THEM IN MEMORY OF HIM BUT I CANT FIND THE BATTERIES FOR THEM PLEASE HELP THE RADIO IN SIDE SAYS I NEED A EVERADY E-640 MALLORY OR EQUIVALIENT TYPE BATTERY MERCURY CELL X-4 PLEASE HELP ME FIND WHATS COMPADABLE TO THESE BATTIRES OR WHERE I CAN FIND OUT ABOUT THEM THANK YOU ,,,,,,GEORGE
Hello.
The original PC640A or PX640A are no longer available.
The 1.35 volt cells were operated in series for 2.7 volts total.
2 AAA or AA cells produce 3.0 volts in series and not only do they work well but even the AAA cells have greater capacity and thus longer life.
I prefer the AA cells in a slide top holder that I used hook and loop to attach to the base back of the radio.
This just looks right, the smaller cells holder is not the right size for that location on the SR H438.
Remember that the electrolytic caps are most likely dead.
It took me an entire afternoon tracing out the parts and an entire day getting things to fit.
But it works and looks "right".
Enjoy!