Note 6 - Revenue From Contracts With Customers - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended														12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	[2]	Jun. 30, 2018	[3],[4]	Mar. 31, 2018	[5]	Dec. 31, 2017	[6],[7]	Sep. 30, 2017	[8]	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Net revenues	$ 18,435		$ 20,160		$ 21,097		$ 18,871		$ 19,381		$ 17,352		$ 15,888	$ 14,180	$ 78,563	$ 66,801
Semiconductor Market [Member]
Net revenues															45,378	37,763
Industrial Market [Member]
Net revenues															21,220	14,148
Telecommunications Market [Member]
Net revenues															5,574	10,262
Other Non-semiconductors Markets [Member]
Net revenues															6,391	4,628
Thermal Testing Products [Member]
Net revenues															25,289	24,657
Induction Heating Products [Member]
Net revenues															24,104	11,915
Semiconductor Production Test Products [Member]
Net revenues															21,445	22,952
Service and Other Products [Member]
Net revenues															7,725	7,277
End User [Member]
Net revenues															68,093	60,731
OEM and Integrators [Member]
Net revenues															$ 10,470	$ 6,070

[1] The quarter ended December 31, 2018 includes a $2,828 increase in the fair value of contingent consideration, which was not deductible for tax purposes.

[2] The quarter ended September 30, 2018 includes $3,057 increase in the fair value of contingent consideration, which was not deductible for tax purposes.

[3] The quarter ended June 30, 2018 includes a $710 reduction in the fair value of contingent consideration, which was not taxable.

[4] The quarter ended June 30, 2018 includes the reversal of certain adjustments originally recorded in the quarter ended December 31, 2017 which were related to tax legislation enacted in December 2017, as discussed in Notes 2 and 12.

[5] The quarter ended March 31, 2018 includes a $1,726 increase in the fair value of contingent consideration, which was not deductible for tax purposes.

[6] The quarter ended December 31, 2017 includes a $7,525 increase in the fair value of contingent consideration, which was not deductible for tax purposes.

[7] The quarter ended December 31, 2017 includes adjustments related to tax legislation enacted in December 2017, as discussed in Note 2 and 12.

[8] The quarter ended September 30, 2017 includes a $549 reduction in the fair value of contingent consideration, which was not taxable.