---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 10/16/21: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:26 AM - Re: Lithium Battery and Alternator Failure (user9253) 2. 09:56 AM - Transponder antenna ground plane (Tom Barter) 3. 02:26 PM - Re: Transponder antenna ground plane (user9253) 4. 02:36 PM - Re: Transponder antenna ground plane (Charlie England) ________________________________ Message 1 _____________________________________ Time: 07:26:30 AM PST US Subject: AeroElectric-List: Re: Lithium Battery and Alternator Failure From: "user9253" Below are the results of a poll taken on VansAirforce. https://vansairforce.net/community/poll.php?do=showresults&pollid=403 Alternator Failures in 250 hours of use: Automotive conversion: 5.6 % Plane Power: 13.5 % B&C: Less than 1 % Due to the small number of respondents, the results might not be statistically significant. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=503541#503541 ________________________________ Message 2 _____________________________________ Time: 09:56:52 AM PST US From: "Tom Barter" Subject: AeroElectric-List: Transponder antenna ground plane Greetings, I'm preparing to install the ground plane for the transponder antenna on my steel tube fabric covered plane. It would be more convenient to mount the transponder antenna ground plane on the inside of the fuselage, on the bottom behind the baggage compartment. This would require a 7/8" thick spacer so the antenna would mount flush with the fabric. If I machined such a spacer from solid aluminum and made sure of low resistance connections between the spacer and the ground plane, would this adversely affect the antenna performance? Any advice appreciated. Tom Barter -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 3 _____________________________________ Time: 02:26:59 PM PST US Subject: AeroElectric-List: Re: Transponder antenna ground plane From: "user9253" Read this thread: http://www.matronics.com/forums/viewtopic.php?t=16762861 I would mount the transponder antenna to a 5.3 inch diameter ground plane. Make sure the outer braid of the coaxial cable is electrically connected to the ground plane. The antenna ground plane does not need to be electrically connected to the tubular steel airframe. Wood could be used between the ground plane and airframe steel tubes to support the antenna where desired. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=503543#503543 ________________________________ Message 4 _____________________________________ Time: 02:36:43 PM PST US Subject: Re: AeroElectric-List: Transponder antenna ground plane From: Charlie England On 10/16/2021 11:55 AM, Tom Barter wrote: > > Greetings, > > Im preparing to install the ground plane for the transponder antenna > on my steel tube fabric covered plane. It would be more convenient to > mount the transponder antenna ground plane on the inside of the > fuselage, on the bottom behind the baggage compartment. This would > require a 7/8 thick spacer so the antenna would mount flush with the > fabric. If I machined such a spacer from solid aluminum and made sure > of low resistance connections between the spacer and the ground plane, > would this adversely affect the antenna performance? > > Any advice appreciated. > > Tom Barter > Have you considered just flipping the assy over, so the xpndr spike points up? Fabric skin does little to attenuate RF, so if you can avoid punching another hole, why not? There might be a little 'shadowing' of the signal if you're too close to an aluminum baggage compartment, but I doubt you'd ever know without taking the plane to an 'antenna range' with a lot of expensive measuring hardware. I've heard of people putting them inside cowlings, and the uAvionix tech recommended that I mount their Echo UAT box, the WAAS GPS, and the antenna spike all on a plate within the fiberglass wingtip of my RV6. Obviously, there's much more shadowing by the wing rib than anything you'd see, and he told me that they have numerous examples flying that way. To answer your actual question, extra aluminum on the back side of the ground plane should have no effect on the antenna's performance. Think of it as a much fatter, stronger 'bulkhead', as you would see inside aluminum skinned a/c near the xpndr antenna mount. FWIW, Charlie -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ------------------------------------------------------------------------------------- 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.