Note 13 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Net revenues	$ 14,443			$ 14,632			$ 38,948	$ 47,046
Earnings (loss) before income tax expense (benefit)	433			794			(777)	1,956
Net earnings (loss)	458	$ 170	$ (1,143)	647	$ (187)	$ 1,138	(515)	1,598
Corporate, Non-Segment [Member]
Earnings (loss) before income tax expense (benefit)	(214)			(177)			(242)	(1,617)
Net earnings (loss)	(139)			(143)			(161)	(1,321)
Thermal Testing Products [Member] | Operating Segments [Member]
Net revenues	10,724			10,622			29,534	33,775
Earnings (loss) before income tax expense (benefit)	478			496			39	1,949
Net earnings (loss)	379			403			26	1,592
EMS [Member] | Operating Segments [Member]
Net revenues	3,719			4,010			9,414	13,271
Earnings (loss) before income tax expense (benefit)	169			475			(574)	1,624
Net earnings (loss)	$ 218			$ 387			$ (380)	$ 1,327