Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net income	$ 1,153	$ 650
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Inventories allowances	(31)	21
Deferred income taxes	195	353
Depreciation and amortization	702	727
Share-based and stock compensation expense	66	34
Restricted stock unit compensation expense	111	41
Loss (gain) on investment in securities	1,392	(1,287)
Loss on disposal of property, plant and equipment	0	94
Changes in operating assets and liabilities:
Trade accounts receivable	(1,883)	(3,584)
Inventories	3,700	(1,257)
Prepaid expenses and other current assets	(869)	567
Other assets	31	(12)
Accounts payable	(2,475)	3,803
Accrued compensation and related taxes	288	(943)
Accrued warranty expense	45	545
Deferred revenue	963	52
Accrued other expenses and other current liabilities	(745)	(49)
Net cash provided by (used in) operating activities	2,643	(245)
Investing activities
Purchases of property, plant and equipment	(1,067)	(572)
Investment in securities	(3,741)	0
Proceeds from sale of available-for-sale securities	8,335	1,819
Net cash provided by investing activities	3,527	1,247
Financing activities
Proceeds from issuance of common stock	0	183
Cash dividends declared and paid	(815)	(2,752)
Repurchase of common stock	(1,153)	(405)
Net cash used in financing activities	(1,968)	(2,974)
Net change in cash and cash equivalents	4,202	(1,972)
Cash and cash equivalents, beginning of period	7,147	10,910
Cash and cash equivalents, end of period	11,349	8,938
Supplemental disclosure
Cash paid for interest	0	0
Income tax paid	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