CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Net sales	$ 11,938	$ 11,087
Cost of sales	8,280	8,131
Gross profit	3,658	2,956
Operating expenses:
Selling expenses	25	53
General and administrative expenses	995	1,024
Research and development costs	805	929
Total operating expenses	1,825	2,006
Operating income	1,833	950
Other income (expense):
Interest and dividend income	24	218
Realized gain on sale of marketable equity investments		6
Unrealized gain (loss) on investments	(2,553)	425
Interest expense	(133)	(130)
Total other income (loss)	(2,662)	519
Income (loss) before income taxes	(829)	1,469
Provision for income taxes	(214)	266
Net income (loss)	$ (615)	$ 1,203
Basic and diluted net income per share:
Basic net income (loss) per share	$ (0.17)	$ 0.33
Diluted net income (loss) per share	$ (0.17)	$ 0.33
Weighted-average common shares outstanding:
Basic	3,546,737	3,616,392
Diluted	3,546,737	3,694,959
Common shares outstanding	3,547,330	3,606,422