Note 16 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended														12 Months Ended
	Dec. 31, 2020	[1]	Sep. 30, 2020	[2]	Jun. 30, 2020	[3]	Mar. 31, 2020	[4]	Dec. 31, 2019	Sep. 30, 2019	[5]	Jun. 30, 2019	[6]	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Net revenues	$ 14,875		$ 14,443		$ 13,275		$ 11,230		$ 13,614	$ 14,632		$ 14,352		$ 18,062	$ 53,823	$ 60,660
Depreciation/amortization															1,863	1,942
Operating income (loss)															(1,217)	2,549
Earnings (loss) before income tax expense (benefit)	(454)		433		183		(1,393)		648	794		(300)		1,462	(1,231)	2,604
Income tax expense (benefit)	(74)		(25)		13		(250)		(76)	147		(113)		324	(336)	282
Net earnings (loss)	$ (380)		$ 458		$ 170		$ (1,143)		$ 724	$ 647		$ (187)		$ 1,138	(895)	2,322
Capital expenditures															658	620
Corporate, Non-Segment [Member]
Depreciation/amortization															27	14
Operating income (loss)															(429)	(1,510)
Earnings (loss) before income tax expense (benefit)															(460)	(1,533)
Income tax expense (benefit)															(126)	(169)
Net earnings (loss)															(334)	(1,364)
Capital expenditures															3	73
Thermal Testing Products [Member] | Operating Segments [Member]
Net revenues															40,209	43,823
Depreciation/amortization															1,727	1,810
Operating income (loss)															325	2,334
Earnings (loss) before income tax expense (benefit)															306	2,370
Income tax expense (benefit)															84	257
Net earnings (loss)															222	2,113
Capital expenditures															371	501
EMS [Member] | Operating Segments [Member]
Net revenues															13,614	16,837
Depreciation/amortization															109	118
Operating income (loss)															(1,113)	1,725
Earnings (loss) before income tax expense (benefit)															(1,077)	1,767
Income tax expense (benefit)															(294)	194
Net earnings (loss)															(783)	1,573
Capital expenditures															$ 284	$ 46

[1] The quarter ended December 31, 2020 includes $1,078 of restructuring and other charges which are discussed in Note 3.

[2] The quarter ended September 30, 2020 includes $161 of restructuring and other charges which are discussed in Note 3.

[3] The quarter ended June 30, 2020 includes $38 of restructuring and other charges which are discussed in Note 3.

[4] The quarter ended March 31, 2020 includes $8 of restructuring and other charges which are discussed in Note 3.

[5] The quarter ended September 30, 2019 includes $17 of restructuring and other charges which are discussed in Note 3.

[6] The quarter ended June 30, 2019 includes $223 of restructuring and other charges which are discussed in Note 3.