CONDENSED CONSOLIDATED INCOME STATEMENTS (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Net sales	$ 14,293	$ 13,079	$ 38,819	$ 35,448
Cost of sales	10,291	9,268	28,357	26,058
Gross profit	4,002	3,811	10,462	9,390
Operating expenses:
Selling expenses	17	24	79	146
General and administrative expenses	1,012	1,009	3,208	2,983
Research and development costs	760	713	2,353	2,109
Total operating expenses	1,789	1,746	5,640	5,238
Operating income	2,213	2,065	4,822	4,152
Interest expense	138	131	409	389
Unrealized gain (loss) on marketable equity investments	(1,192)	242	(3,785)	3,407
Interest and other income	30	11	76	235
Gain on sale of investments	0	0	0	7
Income before income taxes	913	2,187	704	7,412
Income tax expense	258	570	164	1,840
Net income	$ 655	$ 1,617	$ 540	$ 5,572
Basic net income per share:
Net income	$ 0.19	$ 0.46	$ 0.15	$ 1.56
Diluted net income per share:
Net income	$ 0.19	$ 0.45	$ 0.15	$ 1.52
Weighted average common shares outstanding:
Basic	3,451	3,548	3,531	3,580
Diluted	3,524	3,623	3,604	3,656
Common shares outstanding	3,451	3,545	3,451	3,545