---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 08/05/14: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:16 AM - USB "tester" (rayj) 2. 09:17 AM - Re: Panel mounted USB power ports for Apple devices? (Dj Merrill) 3. 12:24 PM - Half wave copper foil dipole transponder antenna (rnbraud) 4. 01:46 PM - Re: Half wave copper foil dipole transponder antenna (Kent or Jackie Ashton) 5. 01:57 PM - Re: Half wave copper foil dipole transponder antenna (rnbraud) 6. 02:41 PM - Re: Re: Half wave copper foil dipole transponder antenna (Kent or Jackie Ashton) 7. 06:27 PM - Re: Half wave copper foil dipole transponder antenna (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 08:16:28 AM PST US From: rayj Subject: AeroElectric-List: USB "tester" I don't know anything about this item: http://www.mpja.com/08-05-14.asp?r=376592&s=4 It looks like it might be useful for those installing usb power outlets. My experience with this supplier has been positive. FWIW -- Raymond Julian Kettle River, MN The things we admire in men, kindness and generosity, openness, honesty, understanding and feeling are the concomitants of failure in our system. And those traits we detest, sharpness, greed, acquisitiveness, meanness, egotism and self-interest are the traits of success. And while men admire the quality of the first they love the produce of the second. -John Steinbeck, novelist, Nobel laureate (1902-1968) ________________________________ Message 2 _____________________________________ Time: 09:17:29 AM PST US Subject: Re: AeroElectric-List: Panel mounted USB power ports for Apple devices? From: Dj Merrill On 8/4/2014 11:49 AM, Dj Merrill wrote: > I ended up hacking the end of the iPad's USB cable to add the > resistors (actually I added a micro-sized potentiometer adjusted to > the proper resistance), which is now dedicated to the airplane, and it > charges the ipad just fine. > > Not difficult, but not as "clean" an installation as I had originally > envisioned. I had an inquiry about how I did this and thought I would share with the group. The micro-sized potentiometer I grabbed from my junk bin and don't remember the exact value, probably 100 ohms or 1K. It isn't critical. Here is the guide I used: http://www.instructables.com/id/THE-Simplest-iPod-iPad-iPhone-charger-circuit/?ALLSTEPS You'll want to read through it for the general idea. I used the "trim pot" method shown in step 4. If you are using the power supply that Bob sent out (http://tinyurl.com/m8kfz6h), all you need is the the trim pot, and none of the other parts mentioned in the article. All you are doing is connecting the middle connection on the trim pot to pins 2 and 3 of the USB cable, and the other two pins on the trim pot go to pin 1 and pin 4 respectively. Then adjust the trim pot until you get a value of 2 volts between the center pin on the trim pot and pin 4 on the USB (which is GND). The right half of this diagram sums it up nicely: http://cdn.instructables.com/FOD/L2X9/HJKBMVWW/FODL2X9HJKBMVWW.LARGE.jpg I added this to the USB cable itself rather than the power supply because the power supply and plugs are all molded plastic and there wasn't an easy way to get inside without making a mess. The USB cable simply had a plastic cover that slid back along the cable and was much easier to work with. When I was finished adjusting the trim pot I put some heat shrink over the entire assembly (USB cable, connector, potentiometer and all) so it is sealed up and won't be accidentally turned. This is similar to the micro-potentiometer that I used: http://www.ebay.com/itm/Horizontal-PCB-Mount-Micro-Potentiometer-Japan-VTG-271-280-Archer-Radio-Shack-/191238164441 -Dj -- Dj Merrill - N1JOV - VP EAA Chapter 87 Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/ Glastar Flyer N866RH - http://deej.net/glastar/ ________________________________ Message 3 _____________________________________ Time: 12:24:12 PM PST US Subject: AeroElectric-List: Half wave copper foil dipole transponder antenna From: "rnbraud" I hope this isn't a duplicate, but I was unable to find sufficient info on this topic in the archives. I have successfully built and tested several copper foil/tape comm antennas for my Cozy MkIV and would like to build a transponder antenna the same way. Will the following work for a Mode S transponder: 1. Vertically oriented 1/2 wave dipole. 2. 1/2" copper tape with ferrites 3. Each leg 6.25" long Thanks. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=428048#428048 ________________________________ Message 4 _____________________________________ Time: 01:46:42 PM PST US Subject: Re: AeroElectric-List: Half wave copper foil dipole transponder antenna From: Kent or Jackie Ashton See. http://www.cozybuilders.org/ref_info/RST_82704.pdf The transponder is a little different than the other antennae. The reference discusses it. Keep the coax run short and put it on the bottom of the airplane. Mine is under removable front seats. You can make the antenna from an AN bolt but they are very cheap on ebay. -kent > On Aug 5, 2014, at 3:23 PM, "rnbraud" wrote: > > > I hope this isn't a duplicate, but I was unable to find sufficient info on this topic in the archives. > > I have successfully built and tested several copper foil/tape comm antennas for my Cozy MkIV and would like to build a transponder antenna the same way. > > Will the following work for a Mode S transponder: > > 1. Vertically oriented 1/2 wave dipole. > 2. 1/2" copper tape with ferrites > 3. Each leg 6.25" long > > Thanks. > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=428048#428048 > > > > > > > > > > ________________________________ Message 5 _____________________________________ Time: 01:57:39 PM PST US Subject: AeroElectric-List: Re: Half wave copper foil dipole transponder antenna From: "rnbraud" Hello Kent, I am trying to avoid the antenna sticking out of the airplane. I see where Advanced Aircraft Electronics makes an "L2" transponder antenna which looks a lot like my other foil tape antennas. I was hoping maybe I could make my own "L2" type of antenna with my leftover RST antenna kit. Just want to confirm if it is feasible and if the leg lengths and vertical orientation is correct. If this does not work, I will make my transponder antenna as you mentioned and place it either out at the end of the strake or right under the pilot seat protruding out of the fuselage. Thanks. kjashton(at)vnet.net wrote: > See. http://www.cozybuilders.org/ref_info/RST_82704.pdf > > The transponder is a little different than the other antennae. The reference discusses it. Keep the coax run short and put it on the bottom of the airplane. Mine is under removable front seats. You can make the antenna from an AN bolt but they are very cheap on ebay. > -kent > > Read this topic online here: http://forums.matronics.com/viewtopic.php?p=428053#428053 ________________________________ Message 6 _____________________________________ Time: 02:41:26 PM PST US Subject: Re: AeroElectric-List: Re: Half wave copper foil dipole transponder antenna From: Kent or Jackie Ashton As I understand it, a ground plane made of copper foils will work as well as the solid ground plane. And vertical orientation sounds right. As for where to put it, just consider that folks who try to put them in the nose of a canard airplane or up front on the airplane often run into problems climbing out away from the radar station because the bodies of the crew (bags of salt-water) and the engine blank off line-of sight with the radar. Quick: When you are 30 miles from a station at 5000', the angle to the station from the horizon is ___. :-) ANS: 1.57 degrees. I doesn't take much nose up deck angle to hide the antenna. Ask me how I know. -Kent On Aug 5, 2014, at 4:56 PM, rnbraud wrote: > > Hello Kent, > > I am trying to avoid the antenna sticking out of the airplane. I see where Advanced Aircraft Electronics makes an "L2" transponder antenna which looks a lot like my other foil tape antennas. > > I was hoping maybe I could make my own "L2" type of antenna with my leftover RST antenna kit. > > Just want to confirm if it is feasible and if the leg lengths and vertical orientation is correct. > > If this does not work, I will make my transponder antenna as you mentioned and place it either out at the end of the strake or right under the pilot seat protruding out of the fuselage. > > Thanks. > > > > kjashton(at)vnet.net wrote: >> See. http://www.cozybuilders.org/ref_info/RST_82704.pdf >> >> The transponder is a little different than the other antennae. The reference discusses it. Keep the coax run short and put it on the bottom of the airplane. Mine is under removable front seats. You can make the antenna from an AN bolt but they are very cheap on ebay. >> -kent >> >> > > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=428053#428053 > > > > > > > > > > ________________________________ Message 7 _____________________________________ Time: 06:27:00 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Half wave copper foil dipole transponder antenna At 02:23 PM 8/5/2014, you wrote: > >I hope this isn't a duplicate, but I was unable to find sufficient >info on this topic in the archives. > >I have successfully built and tested several copper foil/tape comm >antennas for my Cozy MkIV and would like to build a transponder >antenna the same way. > >Will the following work for a Mode S transponder: > >1. Vertically oriented 1/2 wave dipole. yes . . . >2. 1/2" copper tape with ferrites not particularly useful at VHF, useless at uhf >3. Each leg 6.25" long Yeah . . . about that. Suggest you look over the Bob Archer SA-005 descriptions and pictures on the 'net. http://tinyurl.com/mdho4z8 Bob uses double sided ECB material to craft an antenna and matching section all in one piece. As you can see . . . his 'dipole' is rather wide . . . which yields a low SWR over a rather wide frequency range . . . not that you NEED the bandwidth . . . but the wider elements makes their length less critical. Here's Bob's narratives on transponder antennas. http://tinyurl.com/lwgonmx Suggest you consider a dipole of at last 1/2" wide material . . . 1" wouldn't hurt. Assembled onto a sheet of plexiglas and attached to the feedline with a Pawsey stub balun. http://tinyurl.com/lnjhmem http://tinyurl.com/lxzlpky The 'thing' about ferrite beads strung onto the feedline has been popularly circulated through many venues but there are caveats . . . First, the torroid material must be a pretty good performer at the frquency of interest . . . NO torroid materials I'm aware of are suited for service at 1000mHz. Second, the inductance presented by a coil of wire on a core varies as the SQUARE of the turns on the core. Effective use of torroid cores as de-coupling baluns calls for MULTIPLE turns on one core. This picture shows 7 passes of wire through the core for an effective inductance 47x that of a single pass. [] Hence, one would need to string 47 single cores onto the coax as a string of beads to equal the effectiveness of one core wound with seven turns . . . but generally useful only at 200mHz and below. There used to be a commercial vhf comm antenna offered that used the multi-turn torroid de-coupling philosophy. I think it was called the "airwhip" . . . don't find anything about the company now . . . it's been a few years. Now that I have ready access to an EMC lab, any antenna you'd like to fabricate as a shippable assembly could be mailed to me for a quick look-see in the lab. 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