AeroElectric-List Digest Archive

Sun 07/18/10


Total Messages Posted: 6



Today's Message Index:
----------------------
 
     1. 06:10 AM - Re: Electrical Noise Prevention (messydeer)
     2. 08:52 AM - Re: Electrical Noise Prevention (Robert L. Nuckolls, III)
     3. 11:42 AM - Re: Electrical Noise Prevention (messydeer)
     4. 11:45 AM - To balun or not to balun, that IS the question (Robert L. Nuckolls, III)
     5. 06:29 PM - Re: Electrical Noise Prevention (Tim Andres)
     6. 09:42 PM - Avionics Dimmer  (Tim Andres)
 
 
 


Message 1


  • INDEX
  • Back to Main INDEX
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 06:10:01 AM PST US
    Subject: Re: Electrical Noise Prevention
    From: "messydeer" <messydeer@yahoo.com>
    Thanks, Bob :-) -------- Dan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=305278#305278


    Message 2


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 08:52:19 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Electrical Noise Prevention
    At 11:20 PM 7/16/2010, you wrote: > <snip> >How does this look to you? Thanks again for taking your time helping me :-) > > >http://forums.matronics.com//files/cabin_wiring_labeled_836.jpg In this picture you show a "main bus" . . . what is this? Normally, the main bus is a contiguous connection by means of unbroken bar or strip to the power feed side of an array of breakers or fuses. I.e., this component is already in existence inside a fuse block . . . or is fabricated and configured like the bus bars in this photo: http://aeroelectric.com/Pictures/Breakers/Breaker_Panel_Busing_1.jpg You also show a panel ground that appears to be on the side of the fuselage. Is this a floating tie point for the collection of all ground wires off the panel mounted accessories? In the various z-figures, I suggest a gathering of the grounds on what's called a "panel" or "avionics ground bus". This is intended to offer a single point ground for a fist full of wires and centrally located to the serviced accessories (on the panel itself). Further, it is NOT grounded to the panel structure . . . but serves as a handy way to extend lots of grounds to the fire wall ground in fewer wires. For a panel ground, you'd need something like: http://aeroelectric.com/Pictures/Grounding/Avionics_Bus_3.jpg and wired like: http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8Q.pdf where I show 5 strands of 20AWG running from the panel ground to the fire wall ground. This provides redundant, low resistance connection (roughly 2 mOhms/Ft equal to 13AWG) between the two busses. The 5 strands and panel ground provides a much handier way to deal with grounds on the panel mounted accessories. Bob . . .


    Message 3


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 11:42:47 AM PST US
    Subject: Re: Electrical Noise Prevention
    From: "messydeer" <messydeer@yahoo.com>
    > In this picture you show a "main bus" . . . what is this? This is a fuse block fed by a 10awg line from the battery contactor. I had incorrectly called it a 'bus'. Now I know better. > You also show a panel ground that appears to be on > the side of the fuselage. Is this a floating tie point > for the collection of all ground wires off the panel mounted > accessories? The panel ground is made of a section of 'forest of tabs'. I took one 48 tab forest and cut it into 3 pieces. One is on the hot side of the firewall and is connected to another section on the cool side via a 5/16" SS bolt. I forget the exact numbers, but when I measured the resistance of the SS, it was only slightly higher than brass. I chose SS because of its higher melting point. A 10awg ground goes from the inside firewall ground to another section of tab forest for the panel ground. The panel ground is on the outside (lower side) of the cover to the main fuse block a few inches from the side of the fuselage. The cover will be piano hinged to the underside of the glareshield. In the pics, the glareshield is removed, so I've used a bent piece of metal to put the blocks in about the same position. Next step is to wrap all the wires together in a spiral wrap starting from where teh bundle enters the tray on the right side of the fuselage. Feeders and grounds will branch off where shown. -------- Dan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=305327#305327 Attachments: http://forums.matronics.com//files/ground_blocks_951.jpg


    Message 4


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 11:45:32 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: To balun or not to balun, that IS the question
    > >Comments/Questions: I'm installing new VOR antenna and cable and >have a balun question. I see and have studied the balun on your >page, >http://www.matronics.com/aeroelectric/articles/BALUN/Balun_Fabrication.html. > >However the connection arrangement for the old cable arrangement is >the same as in in AC 43.13-2B, Pg 29 >http://www.faa.gov/documentLibrary/media/Advisory_Circular/AC%2043.13-2B.pdf >. It shows the center conductor NOT attached to an antenna pole. > >I plan to use a Garmin SL30 radio. Which balun connection is >best? (and hopefully why?!) I haven't been able to find anything >to support either arrangement, so maybe they're functionally equivalent??? There are a variety of ways to fabricate a balun and some are preferred depending on the impedance matching task (1:1 vs 4:1). The balun shown in 43-13 is one way to do it but I selected the device I published because it was easier to build. One has to be cautious of 43-13 data. For example, on pages 28 and 29 they make references to "airframe ground" . . . on p28, they suggest 4 connections to the airframe. From a radio frequency performance these grounds are not necessary/helpful. On a type certificated airplane one is not allowed to placard the airplane thusly: WARNING: THIS AIRCRAFT IS NOT QUALIFIED TO WITHSTAND DIRECT LIGHTNING STRIKES OF ANY MAGNITUDE. FLIGHT INTO OR IN VICINITY OF CONVECTIVE WEATHER OFFERS SUBSTANTIAL RISK OF HAZARD FROM LIGHTNING AND OTHER UGLY FORCES. ONE IS STRONGLY ADVISED TO REDUCE RISK BY MAINTAINING COMFORTABLE SPACING FROM SUCH CONDITIONS. So, the dedicated acolyte to all things FAR will feel compelled to add "airframe grounds" to things that stick out in the breeze on plastic airplanes. This is irrespective of the fact that at least couple dozen paragraphs describing "Lightning Quality Grounds" is necessary to assist the reader in crafting effective connections for such purposes. In any case, either balun is a 1:1 line impedance transformer so it's your choice. Don't worry about the "airframe ground" . . . unless you enjoy the excitement of Mother Nature's roller coaster rides. Bob . . .


    Message 5


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 06:29:40 PM PST US
    From: "Tim Andres" <tim2542@sbcglobal.net>
    Subject: Electrical Noise Prevention
    Hi Bob and thanks for the help. I am trying to understand your comment re: grounds below. Why is the 5X20 AWG better than a single large wire? And why separate panel and avionics grounds? In my case I had planned either a DB 25 or forest of tabs approach on the front of the (glass) panel with all local ground needs tied in there, then a suitable ground run back to the battery. With a rear mounted battery do you then recommend the 5X20AWG run all the way to the back? For reference I am building an all electric COZY. Thanks, Tim Andres I suggest a gathering of the grounds on what's called a "panel" or "avionics ground bus". This is intended to offer a single point ground for a fist full of wires and centrally located to the serviced accessories (on the panel itself). Further, it is NOT grounded to the panel structure . . . but serves as a handy way to extend lots of grounds to the fire wall ground in fewer wires. For a panel ground, you'd need something like: http://aeroelectric.com/Pictures/Grounding/Avionics_Bus_3.jpg and wired like: http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8Q.pdf where I show 5 strands of 20AWG running from the panel ground to the fire wall ground. This provides redundant, low resistance connection (roughly 2 mOhms/Ft equal to 13AWG) between the two busses. The 5 strands and panel ground provides a much handier way to deal with grounds on the panel mounted accessories. Bob . . .


    Message 6


  • INDEX
  • Back to Main INDEX
  • PREVIOUS
  • Skip to PREVIOUS Message
  • NEXT
  • Skip to NEXT Message
  • LIST
  • Reply to LIST Regarding this Message
  • SENDER
  • Reply to SENDER Regarding this Message
    Time: 09:42:22 PM PST US
    From: "Tim Andres" <tim2542@sbcglobal.net>
    Subject: Avionics Dimmer
    I have discovered the PWM Dimmer I have will not work on at least some of my Garmin equipment. Instead I think I will just use the built in sensing circuits that is available for this purpose. The equipment in question is the GNS 430W, GTX 327, PSA 5000EX and Icom A210. Along with GRT HS displays. I have read elsewhere that the Garmin stuff is fine using the auto dimming, Anyone have experience with this for or against this decision? Thanks, Tim Andres <mailto:rnbraud@yahoo.com>




    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
  • 7-Day List Browse
  •   http://www.matronics.com/browse/aeroelectric-list
  • Browse AeroElectric-List 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.

    -- Please support this service by making your Contribution today! --