Note 17 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023	Dec. 31, 2022
Net revenues	$ 27,884	$ 30,941	$ 32,558	$ 31,919	$ 32,405	$ 30,771	$ 29,571	$ 24,081	$ 123,302	$ 116,828
Earnings before income tax expense	$ 1,566	$ 2,723	$ 3,365	$ 3,394	$ 3,881	$ 3,039	$ 2,570	$ 655	11,048	10,145
Acquired intangible amortization									(2,095)	(2,694)
Interest expense									(679)	(635)
Other income									1,288	59
Operating Segments [Member]
Net revenues									123,302	116,828
Earnings before income tax expense									22,806	21,978
Operating Segments [Member] | Electronic Test [Member]
Net revenues									41,016	40,219
Earnings before income tax expense									10,189	9,931
Operating Segments [Member] | Environmental Technologies [Member]
Net revenues									30,801	30,172
Earnings before income tax expense									3,073	3,817
Operating Segments [Member] | Process Technologies [Member]
Net revenues									51,485	46,437
Earnings before income tax expense									9,544	8,230
Corporate, Non-Segment [Member]
Earnings before income tax expense									$ (10,272)	$ (8,563)