Note 14 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Net revenues	$ 30,941	$ 30,771	$ 95,418	$ 84,423
Earnings before income tax expense	2,723	3,039	9,482	6,264
Earnings before income tax expense	2,723	3,039	9,482	6,264
Acquired intangible amortization	(515)	(595)	(1,582)	(2,142)
Interest expense	168	179	526	457
Other income (expense)	423	59	678	32
Operating Segments [Member]
Net revenues	30,941	30,771	95,418	84,423
Earnings before income tax expense	5,885	5,892	18,328	15,143
Earnings before income tax expense	5,885	5,892	18,328	15,143
Operating Segments [Member] | Electronic Test [Member]
Net revenues	11,547	10,408	32,911	28,983
Earnings before income tax expense	3,268	2,406	8,487	6,486
Earnings before income tax expense	3,268	2,406	8,487	6,486
Operating Segments [Member] | Environmental Technologies [Member]
Net revenues	7,000	7,631	23,178	22,131
Earnings before income tax expense	523	1,021	2,479	2,893
Earnings before income tax expense	523	1,021	2,479	2,893
Operating Segments [Member] | Process Technologies [Member]
Net revenues	12,394	12,732	39,329	33,309
Earnings before income tax expense	2,094	2,465	7,362	5,764
Earnings before income tax expense	2,094	2,465	7,362	5,764
Corporate, Non-Segment [Member]
Earnings before income tax expense	(2,902)	(2,138)	(7,416)	(6,312)
Earnings before income tax expense	$ (2,902)	$ (2,138)	$ (7,416)	$ (6,312)