X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [66.219.56.248] (HELO qnsi-xch.qnsi.net) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTP id 987326 for flyrotary@lancaironline.net; Thu, 16 Feb 2006 10:00:26 -0500 Received-SPF: none receiver=logan.com; client-ip=66.219.56.248; envelope-from=bhughes@qnsi.net Content-class: urn:content-classes:message Return-Receipt-To: "Bobby J. Hughes" MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Disposition-Notification-To: "Bobby J. Hughes" X-MimeOLE: Produced By Microsoft Exchange V6.5.6944.0 Subject: RE: [FlyRotary] Re: Radio noise saga Date: Thu, 16 Feb 2006 09:01:00 -0600 Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [FlyRotary] Re: Radio noise saga Thread-Index: AcYzA5Z2SInGoTidTiCPVSEWKfcPjQABD2ng From: "Bobby J. Hughes" To: "Rotary motors in aircraft" Chad, You are correct with SIGNAL cable. However loaded large DC power cables work differently. EMI can be an issue. If I remember correctly a uniform twist can reduce the problem. But I work mostly with -48VDC in large power plant / load environments and we do not twist power cables. They are however always run side by side as a pair. Bob Knucklos may have more relevant information on this subject but I have never looked at his books. I mostly reference Bellcore / Telcordia standards for DC power signal and grounding since I have access to them. Bobby -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chad Robinson Sent: Thursday, February 16, 2006 8:14 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Radio noise saga Bobby J. Hughes wrote: > I would bet you found the problem. DC power leads should always be run > as a pair. A nice uniform twist is also good but I do not remember how > many twist per foot is recommend. Twisted pair only reduces noise in signals transmitted THROUGH the wire, and it only works if the receiver uses a differential signal. It doesn't help with power wires. The curious can drop by: http://www.duxcw.com/digest/Howto/network/cable/cable4.htm It's a fairly good, brief description of what goes on. You'll usually only find twisted pair in LAN cabling. Regards, Chad -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/