Note 12 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Net revenues	$ 13,275		$ 14,352		$ 24,505	$ 32,414
Earnings (loss) before income tax expense (benefit)	183		(300)		(1,210)	1,162
Net earnings (loss)	170	$ (1,143)	(187)	$ 1,138	(973)	951
Corporate, Non-Segment [Member]
Earnings (loss) before income tax expense (benefit)	(65)		(711)		(28)	(1,440)
Net earnings (loss)	(53)		(610)		(22)	(1,178)
Thermal Testing Products [Member] | Operating Segments [Member]
Net revenues	9,476		10,519		18,810	23,153
Earnings (loss) before income tax expense (benefit)	(13)		309		(439)	1,453
Net earnings (loss)	(3)		298		(353)	1,189
EMS [Member] | Operating Segments [Member]
Net revenues	3,799		3,833		5,695	9,261
Earnings (loss) before income tax expense (benefit)	261		102		(743)	1,149
Net earnings (loss)	$ 226		$ 125		$ (598)	$ 940