CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Net sales	$ 8,265	$ 7,961	$ 16,855	$ 15,201
Cost of sales	5,669	5,097	10,784	9,557
Gross profit	2,596	2,864	6,071	5,644
Operating expenses:
Selling expenses	150	135	280	277
General and administrative expenses	936	664	1,641	1,327
Research and development costs	989	397	2,080	881
Total operating expenses	2,075	1,196	4,001	2,485
Operating income	521	1,668	2,070	3,159
Interest expense	(75)	(63)	(129)	(122)
Interest and other income	20	33	61	68
Gain on sale of investments			12
Income from operations before income taxes	466	1,638	2,014	3,105
Income tax expense	(129)	(389)	(412)	(751)
Net income	337	1,249	1,602	2,354
Other comprehensive income, net of tax:
Unrealized income from marketable equity investments	1,413	705	1,306	649
Comprehensive income	$ 1,750	$ 1,954	$ 2,908	$ 3,003
Basic net income per share:
Net income	$ 0.09	$ 0.32	$ 0.42	$ 0.59
Diluted net income per share:
Net income	$ 0.08	$ 0.31	$ 0.4	$ 0.58
Weighted average common shares outstanding:
Basic	3,861	3,950	3,856	3,979
Diluted	4,012	4,053	4,014	4,082
Common shares outstanding	3,861	3,884	3,861	3,884