Highfields Amateur Radio Club
Glossary of Radio Terms.

Appendix:
Battery Details.

Originally a 1.35 volts Mercury cell commonly used in cameras and some watches and is now banned because of toxicity and environmental fears.

There are 3 possible replacements for the PX400 cell:

1. The equivalent Silver Oxide cell, the S400PX, at 1.55 volts.
2. The equivalent zinc air cell, the WeinCELL MRB400 at 1.35 volts.
3. The Accucell-1, developed to output the proper voltage to run watch movements exactly as would the original Mercury cell.

WeinCELLs are only suitable for cameras and light meters, they are not suitable for watches.

Although the Accucell-1 uses Silver Oxide chemistry it also has built in voltage reduction to bring the voltage into specification.

The 387S has a distinctive appearance appearance and wears a plastic collar designed to adapt the 394 Silver Oxide battery to the size of the PX400 (see picture).

Equivalents:

Image not to scale.	Common Name.	Dimensions. Length × Diameter.	Chemical Composition.	Nominal Voltage.
	PX400.	11.2 mm × 3.6 mm Contacts: Case and flat base Positive Slightly raised area Negitive.	Silver Oxide (Ag2O), or Zinc Air replacement for original Mercury.	1.55 volts (Ag2O). 1.35 volts (Zinc Air and Accucell-1), (1.35 volts for the discontinued Mercury types).