Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (195)	$ (3,626)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Inventory allowance	(38)	149
Deferred tax benefit	(178)	(1,163)
Depreciation and amortization	921	942
Share-based compensation expense	95	55
Restricted stock unit compensation expense	153	76
Loss (gain) on sale of available-for-sale securities	2,671	(1,833)
Loss on disposal of property, plant and equipment	0	95
Changes in operating assets and liabilities:
Trade accounts receivable	(197)	(2,076)
Inventories	2,930	(508)
Prepaid expenses and other current assets	(1,629)	637
Other assets	53	(20)
Accounts payable	(376)	3,998
Accrued compensation and related taxes	650	(829)
Accrued warranty expense	157	739
Deferred revenue	1,138	88
Accrued other expenses and other current liabilities	(867)	990
Net cash provided by (used in) operating activities	5,288	(2,286)
Investing activities
Purchases of property, plant and equipment	(1,396)	(628)
Investment in securities	(3,741)	0
Proceeds from sale of available-for-sale securities	8,335	2,642
Net cash used in investing activities	3,198	2,014
Financing activities
Dividends paid	(1,083)	(3,026)
Repurchase of common stock	(3,282)	(648)
Proceeds from issuance of common stock	0	183
Net cash used in financing activities	(4,365)	(3,491)
Net change in cash and cash equivalents	4,121	(3,763)
Cash and cash equivalents, beginning of year	7,147	10,910
Cash and cash equivalents, end of year	11,268	7,147
Supplemental disclosure
Cash paid for income taxes	0	0
Non-cash financing activity
Restricted stock units issued	140	0
Cashless exercise of stock options and related conversion of net shares to stockholders’ equity	$ 0	$ 27