---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Tue 01/28/20: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:55 AM - Re: Rotax 914 UMA Differential Pressure Transducer Failure? (Remi Guerner) 2. 04:57 AM - Re: Comm Antennas (h&jeuropa) 3. 10:35 AM - Re: Re: Comm Antennas (Martin Tuck) 4. 12:29 PM - Re: Strobes (Paul Mansfield) 5. 12:41 PM - Re: Comm Antennas (h&jeuropa) ________________________________ Message 1 _____________________________________ Time: 12:55:02 AM PST US Subject: Europa-List: Re: Rotax 914 UMA Differential Pressure Transducer Failure? From: "Remi Guerner" Mine failed twice, first time after 30 hours, indicating zero, replaced under warranty, then after 300hours started to give false readings, replaced with a steam gauge. It was installed on the firewall, see attached picture. Note the engine is a 912ULS, but the UMA sensor is the same as the one for the 914, except that it is vented to the cowling atmosphere instead of the airbox. Remi Read this topic online here: http://forums.matronics.com/viewtopic.php?p=494496#494496 Attachments: http://forums.matronics.com//files/p5080006a__copie_723.jpg ________________________________ Message 2 _____________________________________ Time: 04:57:35 AM PST US Subject: Europa-List: Re: Comm Antennas From: "h&jeuropa" Hi Martin, Boy, those are surprising results! I too used a MFJ analyzer with good results. Im assuming when you measured resonate frequency you mean that was the frequency with the lowest SWR. To start, verify that the frequency calibration of the MFJ is close. Attach a dummy load (can be 3 150 ohm resistors in parallel or a simple dipole) and sweep across the com frequencies while listening on a hand held or your comm radio. There is no modulation on the MFJ but you should hear something. If the MFJ calibration is close, as I expect it is, then you need to tune your antennas. For the whip on the belly, be sure you have a good ground plane. Bob Nuckolls does a pretty good job explaining how a dipole works and what constitutes a ground plane. Have a look at page 13-11 of AeroElectric Connection book for details. If you have something similar and there is no corrosion and the connection to the coax is good (assuming you are using RG58 or RG400 coax and the connector is properly attached), then you need to trim your whip. It should start at about 22 inches long. Try just taking off " to 3/8 and see what difference that makes. Fortunately your antenna is too long! Im really surprised at the Bob Archer antenna. Did you test it installed or just sitting on a table? Remember any metal near it will affect it. This thread from VAF in post 7 has instructions on how to tune a Bob Archer antenna using a MFJ 259! http://www.vansairforce.com/community/showthread.php?t=142149&highlight=tuning+bob+archer It is a bit more complicated since the length will determine the resonant frequency but the gamma matching circuit will determine the SWR. Although the antenna is new, be sure there is no corrosion where the aluminum bits are riveted together. Finally, you can construct a simple dipole per AEC using solid copper house wire (12-14 gauge) and solder RG58 or RG400 coax to it. Don't worry about a balun or torrids, this is just for testing and education. Just tape the elements to a piece of wood. Lead the coax at 90 deg to the elements. See what the MFJ says about it and try trimming to see the effect. You might want to do this first to get some confidence in what you are doing:) I hope some of this helps. Probably whoever loaned you the MFJ can assist. Jim Butcher Read this topic online here: http://forums.matronics.com/viewtopic.php?p=494497#494497 ________________________________ Message 3 _____________________________________ Time: 10:35:47 AM PST US From: Martin Tuck Subject: Re: Europa-List: Re: Comm Antennas Thanks Jim, some good information there. Im suspecting possible corrosion or just bad contact with the whip antenna. I also suspect that the aluminum tubing which used to be the static port hook up might be messing with the Bob Archer As it is in very close proximity - might even be touching! Im also planning to try out an Advanced Aircraft Electronics high gain antenna from Aircraft Spruce which does not require a ground plane and recommended for composite aircraft. Regards, Martin Sent from my iPhone > On Jan 28, 2020, at 12:07 PM, h&jeuropa wrote: > > > Hi Martin, > > Boy, those are surprising results! I too used a MFJ analyzer with good results. > > Im assuming when you measured resonate frequency you mean that was the frequency with the lowest SWR. > > To start, verify that the frequency calibration of the MFJ is close. Attach a dummy load (can be 3 150 ohm resistors in parallel or a simple dipole) and sweep across the com frequencies while listening on a hand held or your comm radio. There is no modulation on the MFJ but you should hear something. > > If the MFJ calibration is close, as I expect it is, then you need to tune your antennas. > > For the whip on the belly, be sure you have a good ground plane. Bob Nuckolls does a pretty good job explaining how a dipole works and what constitutes a ground plane. Have a look at page 13-11 of AeroElectric Connection book for details. If you have something similar and there is no corrosion and the connection to the coax is good (assuming you are using RG58 or RG400 coax and the connector is properly attached), then you need to trim your whip. It should start at about 22 inches long. Try just taking off " to 3/8 and see what difference that makes. Fortunately your antenna is too long! > > Im really surprised at the Bob Archer antenna. Did you test it installed or just sitting on a table? Remember any metal near it will affect it. This thread from VAF in post 7 has instructions on how to tune a Bob Archer antenna using a MFJ 259! > > http://www.vansairforce.com/community/showthread.php?t=142149&highlight=tuning+bob+archer > > It is a bit more complicated since the length will determine the resonant frequency but the gamma matching circuit will determine the SWR. Although the antenna is new, be sure there is no corrosion where the aluminum bits are riveted together. > > Finally, you can construct a simple dipole per AEC using solid copper house wire (12-14 gauge) and solder RG58 or RG400 coax to it. Don't worry about a balun or torrids, this is just for testing and education. Just tape the elements to a piece of wood. Lead the coax at 90 deg to the elements. See what the MFJ says about it and try trimming to see the effect. You might want to do this first to get some confidence in what you are doing:) > > I hope some of this helps. Probably whoever loaned you the MFJ can assist. > > Jim Butcher > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=494497#494497 > > > > > > > > > ________________________________ Message 4 _____________________________________ Time: 12:29:52 PM PST US From: Paul Mansfield Subject: Re: Europa-List: Strobes My last attempt was mangled by Android... try again: Hello Mike, I'd recommend Aveo strobes - LED and no separate strobe power box needed. https://www.aveoengineering.com/lsa-experimental-ul-kits-and-gliders/ I have the Minimax on the fin and I guess it would work as well on top and bottom of the fuse. https://www.aveoengineering.com/lsa-experimental-ul-kits-and-gliders/minimax-ariel/ HTH, Paul M G-PLPM Permit to test received! On Thu, 23 Jan 2020 at 11:43, Mike Wylde wrote: > Hi all, I've been lurking for a while, now my first post looking for > advice please. > I've recently bought a nearly finished (yes, it is, really!) XS trigear > with a 912ULS. > I'd like to fit strobes on top and bottom of the fus. Clearly each needs a > hemispherical (or doughnut) light pattern, but I want streamlined > teardrops, not round beacons. I can find 3 possibles. > Only one is LED. That's the Kuntzleman (badged Skyflash in the UK by > Airworld/Sandalwood). https://www.kestrobes.com/all-led-systems/ Looking > at the distribution of LEDs in it, I suspect a lot of the flash would go > vertically and the important doughnut distribution would be less bright. > Of course it's really meant for wingtip mounting. Anyone tried it please? > Second possibility is the Kuntzleman /Skyflash discharge tube type. I > reckon that will give a better distribution as the tube is exposed and non > directional. https://www.kestrobes.com/double-dual-magnum/ Anyone know > how many joules it is per flash please? I've asked but Mr K wouldn't give > me a number. > Third possibility is the similar MicroAvionics discharge tube type (UK > produced). Like the Kuntzleman it gives you a double flash alternating. > Each individual flash is 25 joules i.e 50 joules per double flash cycle per > lamp. It's pretty bright, I suspect the K is lower power. > https://www.microavionics.com/twin-head-high-power-strobe.html > I would have preferred LED but I think it may be less effective. > The K flash tube one has the slight advantage of being a LAA standard mod > needing no further approval. > The MicroAvionics may be the best, I've used one, I'm impressed with its > output, but it means getting approval. > I'm in a quandary! All advice and experience gratefully received, > apologies for the rather long post. > Mike > > ________________________________ Message 5 _____________________________________ Time: 12:41:34 PM PST US Subject: Europa-List: Re: Comm Antennas From: "h&jeuropa" Martin, I'd like to suggest you make a simple dipole of copper ribbon like the one shown in the build manual annex C. You can omit the ferrite beads. Place it so the copper ribbon is vertical with the coax connection near the fuselage joint. Put it as far forward in the rear as you can, close to the D panel. The ends of the copper ribbon will wrap on the top and the bottom of the fuselage but most of the radiating section will be vertical. Be sure there is nothing metallic near or touching it. Use the MFJ to adjust the length. You can purchase the copper ribbon from RST Engineering or ACS. ACS has a Quickie Kit that appears to have the ribbon, ferrites, coax and connectors. Jim Read this topic online here: http://forums.matronics.com/viewtopic.php?p=494513#494513 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message europa-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Europa-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/europa-list Browse Digests http://www.matronics.com/digest/europa-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.