---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 06/10/19: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:02 AM - Re: Re: Aera 660 Bare Wire Cradle Question (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 08:02:56 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Aera 660 Bare Wire Cradle Question > >but the current installation manual, dated 6 months later, states: >"A three conductor shielded cable 24 AWG or heaver, Hmmm . . . . Given the short runs and low power levels it seems unlikely that anyone experienced degraded performance as a consequence of voltage drops. However 24 AWG is about the smallest practical size for hand-assembled wiring and even that was not well received on our production lines at RAC/Beech. I've personally never designed an airframe harnesses with smaller than 22AWG wire . . . works good, lasts a long time, easy to work with. >(Aircraft Spruce P/N 11-04478 or equivalent) should be used to connect >the ELT RS 232 data and power to the aircraft systems=853.) Connect one >conductor to pin 3 (Fig. 12.1) and connect to aircraft ground at the >cockpit. connect the outer shield to ground, at the cockpit end only." In what document does figure 12.1 appear? I'd like to look at it if it's downloadable . . . This is best practice . . . unless the shield is a CONDUCTOR of data or power by design. I.e. I used to build a lot of RS232 runs from 22AWG shielded, twisted pair where the shield was used as signal ground for the TX/RX pair. But if the shield is simply a prophylactic against electro-static coupling of noise, then a ground at one end will suffice and avoid other potential difficulties with ground loop currents on the shield (a potential problem on large, all metal aircraft . . . something I've never seen but it was talked about in EMC class). In any case, the best approach is to follow the manufacture's installation instructions unless you've been made aware of some error on the part of the folks who wrote the manual. >If using individual wires, should the shield be >grounded at both ends or just at the aircraft >ground as if using the three conductor cable? A you planning on building your own shielded run of wires? > Also, if using the three conductor cable, what would be the best >way to separate the 232 data wire from the power and ground wires? Don't understand. One cable would carry RS-232 . . . an independent cable would carry power . . . no physical 'separation' necesasry. > They will not be connecting at the same place since the power >source is not coming via the 660 cradle harness. Not a problem Bob . . . ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.