CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Net sales	$ 10,173	$ 8,265	$ 20,161	$ 16,855
Cost of sales	6,769	5,669	13,329	10,784
Gross profit	3,404	2,596	6,832	6,071
Operating expenses:
Selling expenses	22	150	59	280
General and administrative expenses	1,165	936	2,257	1,641
Research and development costs	615	989	1,596	2,080
Total operating expenses	1,802	2,075	3,912	4,001
Operating income	1,602	521	2,920	2,070
Interest expense	(117)	(75)	(237)	(129)
Unrealized gain (loss) on marketable equity investments	(300)	1,413	(152)	1,306
Interest and other income	25	20	49	61
Gain on sale of investments				12
Income from operations before income taxes	1,210	1,879	2,580	3,320
Income tax expense	(285)	(129)	(592)	(412)
Net income	$ 925	$ 1,750	$ 1,988	$ 2,908
Basic net income per share:
Net income	$ 0.25	$ 0.45	$ 0.54	$ 0.75
Diluted net income per share:
Net income	$ 0.25	$ 0.44	$ 0.53	$ 0.72
Weighted average common shares outstanding:
Basic	3,657	3,861	3,654	3,856
Diluted	3,767	4,012	3,774	4,014
Common shares outstanding	3,642	3,861	3,642	3,861