Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net (loss) income	$ (1,327)	$ 1,153
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Inventories allowances	112	(31)
Deferred tax benefit	(416)	195
Depreciation and amortization	896	702
Share-based compensation expense	110	66
Restricted stock unit compensation expense	85	111
(Gain) loss on investment in securities	(186)	1,392
Changes in operating assets and liabilities:
Trade accounts receivable	2,850	(1,883)
Inventories	(3,096)	3,700
Prepaid expenses and other current assets	609	(869)
Other assets	(31)	31
Accounts payable	1,259	(2,475)
Accrued compensation and related taxes	(854)	288
Accrued warranty expense	(156)	45
Deferred revenue	924	963
Accrued other expenses and other current liabilities	220	(745)
Net cash provided by operating activities	999	2,643
Investing activities
Purchases of property, plant and equipment	(2,301)	(1,067)
Investment in securities	0	(3,741)
Proceeds from sale of available-for-sale securities	0	8,335
Net cash (used in) provided by investing activities	(2,301)	3,527
Financing activities
Proceeds from note payable	425	0
Proceeds from issuance of common stock	2	0
Cash dividends declared and paid	(765)	(815)
Repurchase of common stock	(803)	(1,153)
Net cash used in financing activities	(1,141)	(1,968)
Net change in cash and cash equivalents	(2,443)	4,202
Cash and cash equivalents, beginning of period	11,268	7,147
Cash and cash equivalents, end of period	8,825	11,349
Supplemental disclosure
Cash paid for interest	2	0
Income tax paid	0	0
Non-cash financing activity
Restricted stock units issued	$ 168	$ 140