Its export and domestic markets booming, Ametherm Inc. was running out of space in its manufacturing facility in Carson City."We were at capacity last summer," says Eric Rauch, president of the maker of thermistors used in electric products ranging from battery chargers to big stadium speakers. "We could not build another part."The upshot: Ametherm headed off to its bank, becoming one of a slowly growing number of companies in the region making applications for loans to finance growth.Working with lenders at City National Bank, Ametherm nailed down Small Business Administration financing for a 34,000-square-foot building on Fairview Drive in southern …