Business segment information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 28, 2014	Mar. 29, 2013
Segment Reporting Information [Line Items]
Total Net sales	$ 81,652	$ 84,806
Severance, impairment and other associated costs	961	19
Legal reserve	11	38
Operating (loss) profit	(1,368)	950
Interest expense, net	(7,118)	(5,114)
Other expense, net	(73)	(2,532)
Loss before income taxes	(8,559)	(6,696)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Net sales	81,652	84,806
Operating profit (loss) excluding severance, impairment and other associated costs, and legal reserve costs:	(396)	1,007
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Severance, impairment and other associated costs	961	19
Legal reserve	11	38
Network [Member]
Segment Reporting Information [Line Items]
Total Net sales	34,942	35,831
Operating profit (loss) excluding severance, impairment and other associated costs, and legal reserve costs:	931	1,332
Power [Member]
Segment Reporting Information [Line Items]
Total Net sales	26,487	27,585
Operating profit (loss) excluding severance, impairment and other associated costs, and legal reserve costs:	1,317	1,169
Wireless [Member]
Segment Reporting Information [Line Items]
Total Net sales	20,223	21,390
Operating profit (loss) excluding severance, impairment and other associated costs, and legal reserve costs:	$ (2,644)	$ (1,494)