Eaton will buy a Westlake Village defense firm.

The Cleveland-based conglomerate said it will pay $23.7 million, or $3.03 a share, for American Nucleonics and will operate it as a wholly owned subsidiary. American Nucleonics, which makes electronic equipment used by the military to reduce interference in radio transmissions, earned $974,000 on sales of $4.8 million in the third quarter ended May 31. About 60% of American Nucleonics’ stock is held by Monsanto, Aetna and Emerson Electric.