---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 12/20/12: 13 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:25 AM - TV Antennas in parallel (user9253) 2. 08:34 AM - Wire too short? Just stretch it a bit... (Dj Merrill) 3. 09:56 AM - Re: RF interference on GRT fuel pressure with PTT (Tim Andres) 4. 10:39 AM - Re: RF interference on GRT fuel pressure with PTT (Robert L. Nuckolls, III) 5. 10:42 AM - FSDO horror shows (Owen Baker) 6. 10:46 AM - Re: TV Antennas in parallel (Sam Marlow) 7. 12:17 PM - Re: TV Antennas in parallel (Harley) 8. 05:02 PM - Re: FSDO horror shows (DVS) 9. 05:42 PM - Re: TV Antennas in parallel (user9253) 10. 05:47 PM - Re: FSDO horror shows (Ed Holyoke) 11. 06:39 PM - Re: TV Antennas in parallel (John MacCallum) 12. 08:18 PM - Re: Fw: Iron-Constantan oil temp gauge (nuckollsr) 13. 10:42 PM - Re: Re: Fw: Iron-Constantan oil temp gauge (Dave Saylor) ________________________________ Message 1 _____________________________________ Time: 08:25:24 AM PST US Subject: AeroElectric-List: TV Antennas in parallel From: "user9253" This is not aviation related, but may be of interest to electron herders. Cable is not available at my location. I get TV signals from antennas in the attic. I read some place that two antennas can be connected together if the feed lines are of equal length. I took it one step further and connected 3 antennas together using equal ( 8 foot) lengths of 300 ohm twin-lead TV antenna cable. The 3 antennas point in different directions. I was surprised to receive even more stations than I had hoped for, a total of 34 counting the sub-channels, all with digital quality. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=390745#390745 ________________________________ Message 2 _____________________________________ Time: 08:34:34 AM PST US Subject: AeroElectric-List: Wire too short? Just stretch it a bit... From: Dj Merrill We've been making the joke for years that if a wire is just a little bit too short, pull on it and stretch it a little bit to make it fit. Well, this group took that to a whole new level: http://news.ncsu.edu/releases/wms-dickey-stretch-wire/ -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: 09:56:27 AM PST US From: Tim Andres Subject: Re: AeroElectric-List: RF interference on GRT fuel pressure with PTT Hi Bob This post from several weeks ago but Id like to revisit it please, I plan to try to fix this problem soon. Again the problem is fuel pressure indication spike on transmit from either comm at the higher end of the band. The engine monitor connector is a DB-25. My plan is to install the capacitor listed between the fuel pressure "Aux" input and ground pins inside the connector if possible using short-as-possible lead length, then a split toroid on the wire bundle coming into the DB-25connector. Thanks for any clarification, Tim ________________________________ > > If it makes you feel better I have the same problem. On mine it only occurs >when on the upper end of the band, like center frequencies above 130 MHz, and >happens when I key either the 430W or Icom A210 on those upper frequencies. > I spoke to Carlos at GRT about this and he suggested the split ferrite that >you have tried. I have not attempted to fix it yet and was about to ask the >group what specs I need when I buy it. > I wonder if a small capacitor could be used to drain off the RF since the >torrid didn't work. It could be installed inside the D-sub between the fuel >sensor pin and ground. Can anyone here tell if this might work and if so what >cap to use? The value of such capacitors is not so critical as their construction. A few days ago I published a capacitors-in-the-connector fix that I crafted on a Hawker 800 a few years back. See http://tinyurl.com/dxeuj6b and scroll down to bottom for pictures. Those capacitor were monolythic ceramics, 0.1 uF at 50 volts. But probably any value between 0.01 and 0.47 would have worked. What we're interested in is tiny size so that they can make short lead connection to the pin and low inductance characteristics for which the monolythic construction is noted. Radio Shack used to stock a 0.1 uf cerami (about 1.5 times size of a paper match head). Here's an exemplar part http://tinyurl.com/bsk27pw Ferrites are a whole other ball game. They tend to improve on an RFI problem with a combination of two characteristics. (1) they add a lumped inductance into the wire or wires that are coupling the energy into the victim (or out of the antagonist). (2) Ferrites designed for RFI mitigation are TERRIBLE transformer cores. I.e. they're designed to be very lossy at the frequencies of interest. By lossy, we mean that energy coupled into the core is converted to heat. BOTH effects are enhanced by the capacitor that lowers the parallel impedance against which the series impedance of the ferrite can work. The BEST ferrite in the world does nothing if the downstream path to the victim is a high impedance at the frequency of interest. This is why the odds are so long that ferrites alone will fix a problem. The problem would not have existed had the victim's i/o leads been designed for that environment in the first place. So the best moves call for capacitors first with ferrites stacked on top. Bob . . . ________________________________ Message 4 _____________________________________ Time: 10:39:52 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: RF interference on GRT fuel pressure with PTT At 11:53 AM 12/20/2012, you wrote: >Hi Bob >This post from several weeks ago but Id like to revisit it please, I >plan to try to fix this problem soon. >Again the problem is fuel pressure indication spike on transmit from >either comm at the higher end of the band. >The engine monitor connector is a DB-25. My plan is to install the >capacitor listed between the fuel pressure "Aux" input and ground >pins inside the connector if possible using short-as-possible lead >length, then a split toroid on the wire bundle coming into the DB-25connector. >Thanks for any clarification, Tim Try just the capacitor first. Add only one component at a time to make sure that you know the benefit of each. I've had readers report that a whole lot of "stuff" in an RFI mitigation experiment was "successful" leaving me wondering how much of that stuff could be taken out without reducing the degree of success. Bob . . . ________________________________ Message 5 _____________________________________ Time: 10:42:31 AM PST US From: "Owen Baker " Subject: AeroElectric-List: FSDO horror shows 12/20/2012 Hello Ed Holyoke, You wrote: =9CA friend of mine was quizzed severely before they would issue his Repairman's Cert. The thrust was that he hadn't built the plane himself and was fraudulently applying for the R.C=9D Why would your friend expect to be issued a Repairman=99s Certificate for an experimental amateur built aircraft if he had not built the plane himself? See here: http://www.faa.gov/aircraft/gen_av/ultralights/amateur_built/repairman_ce rt/ Thanks, OC 'O C' Baker says "The best investment you can make is the effort to gather and understand information." ________________________________ Message 6 _____________________________________ Time: 10:46:40 AM PST US From: Sam Marlow Subject: Re: AeroElectric-List: TV Antennas in parallel Where did you purchase your antennas? user9253 wrote: > > This is not aviation related, but may be of interest to electron herders. > Cable is not available at my location. I get TV signals from antennas in the attic. I read some place that two antennas can be connected together if the feed lines are of equal length. I took it one step further and connected 3 antennas together using equal ( 8 foot) lengths of 300 ohm twin-lead TV antenna cable. The 3 antennas point in different directions. I was surprised to receive even more stations than I had hoped for, a total of 34 counting the sub-channels, all with digital quality. > Joe > > -------- > Joe Gores > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=390745#390745 > > ________________________________ Message 7 _____________________________________ Time: 12:17:53 PM PST US From: Harley Subject: Re: AeroElectric-List: TV Antennas in parallel I did the same thing that Joe did, but with only two antennas...I get 32 channels over the air (again, including the subchannels), here just south of Rochester NY, most from Rochester, but some of them from Buffalo. I didn't buy the antennas, I made them, and mounted them in the crawl space above my ceiling, pointing North and West (although, unlike the instructions, I used old wire coat hangars for the wire, didn't use screws and washers to connect but scraped the enamel off where contact was needed and soldered them together, and bent them so the cross wires don't touch...didn't use any shrink tubing): www.popularmechanics.com/technology/how-to/tv/build-your-own-digital-tv-antenna You can also find a number of video instructions to make these on Youtube. And they do work better than any commercial ones I've used in the past. I am thinking of dropping Dish Network, as several of the channels I receive here over the air are also on Dish (Ion for example)! Harley ----------------------------------------------------------------- On 12/20/2012 1:47 PM, Sam Marlow wrote: > > > Where did you purchase your antennas? > > user9253 wrote: >> >> >> This is not aviation related, but may be of interest to >> electron herders. >> Cable is not available at my location. I get TV signals from >> antennas in the attic. I read some place that two antennas >> can be connected together if the feed lines are of equal >> length. I took it one step further and connected 3 antennas >> together using equal ( 8 foot) lengths of 300 ohm twin-lead >> TV antenna cable. The 3 antennas point in different >> directions. I was surprised to receive even more stations >> than I had hoped for, a total of 34 counting the sub-channels, >> all with digital quality. >> Joe >> >> -------- >> Joe Gores >> >> >> >> >> Read this topic online here: >> >> http://forums.matronics.com/viewtopic.php?p=390745#390745 >> >> >> >> >> >> >> >> >> >> >> > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Date: 12/19/12 > > ________________________________ Message 8 _____________________________________ Time: 05:02:18 PM PST US From: "DVS" Subject: RE: AeroElectric-List: FSDO horror shows Oc Read Ed=99s post again. He did not say that his friend did not build the aircraft. The FAA wanted more proof than is normally required. The repair cert is in my possession at this time. dFrom: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Owen Baker Sent: Thursday, December 20, 2012 10:42 AM aeroelectric-list@matronics.com Subject: AeroElectric-List: FSDO horror shows 12/20/2012 Hello Ed Holyoke, You wrote: =9CA friend of mine was quizzed severely before they would issue his Repairman's Cert. The thrust was that he hadn't built the plane himself and was fraudulently applying for the R.C=9D Why would your friend expect to be issued a Repairman=99s Certificate for an experimental amateur built aircraft if he had not built the plane himself? See here: http://www.faa.gov/aircraft/gen_av/ultralights/amateur_built/repairman_ce rt/ Thanks, OC 'O C' Baker says "The best investment you can make is the effort to gather and understand information." ________________________________ Message 9 _____________________________________ Time: 05:42:32 PM PST US Subject: AeroElectric-List: Re: TV Antennas in parallel From: "user9253" > Where did you purchase your antennas? I do not remember where I bought them. They have been in the attic for years. Long ago there were 3 sets of lead-in cables connected to a RF A-B-C switch behind the TV. Now the A-B-C switch is not needed. There is only one lead-in cable used. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=390764#390764 ________________________________ Message 10 ____________________________________ Time: 05:47:03 PM PST US From: Ed Holyoke Subject: Re: AeroElectric-List: FSDO horror shows No, no, no. He wasn't fraudulently applying for the cert. He built the plane. They just didn't want to believe him. Said that pictures of him with tools in his hands and the aircraft under construction could have been faked. Asked him questions about mechanical stuff on certificated aircraft as if he was trying to sell himself as an A&P. Ed On 12/20/2012 10:42 AM, Owen Baker wrote: > 12/20/2012 > Hello Ed Holyoke, You wrote: > *A friend of mine was quizzed severely before they would issue his > Repairman's Cert. The thrust was that he hadn't built the plane > himself and was fraudulently applying for the R.C* > ** > *Why would your friend expect to be issued a Repairmans Certificate > for an experimental amateur built aircraft if he had not built the > plane himself? See here:* > ** > ** > http://www.faa.gov/aircraft/gen_av/ultralights/amateur_built/repairman_cert/ > Thanks, > OC > 'O C' Baker says "The best investment you can make is the effort to > gather and understand information." > * > > > * ________________________________ Message 11 ____________________________________ Time: 06:39:48 PM PST US From: John MacCallum Subject: RE: AeroElectric-List: TV Antennas in parallel Hi Joe, That is a good outcome but usually you just can't add antennas in parallel like that due to Impedance and phasing mismatches. The feedlines need to be matched to the frequency you are working at and be either 1/4 wave or 1/2 wavelength multiples depending on The antenna configuration and not just be equal lengths. The characteristic feed line impedance in your 300 ohm hook up will be way off and it will not be 100 ohms as is suggested by simple Mathematics and as well the impedance will also vary with frequency. Multipath will cause issues with such a setup and the antennas will have multiple lobes and nulls. Being in the attic instead of outside is less than ideal to boot. But if it works it works! Just don't expect it to work at other locations with the same degree of success. Cheers John MacCallum VH-DUU RV 10 # 41016 VK2GCN -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of user9253 Sent: Friday, 21 December 2012 3:24 AM Subject: AeroElectric-List: TV Antennas in parallel This is not aviation related, but may be of interest to electron herders. Cable is not available at my location. I get TV signals from antennas in the attic. I read some place that two antennas can be connected together if the feed lines are of equal length. I took it one step further and connected 3 antennas together using equal ( 8 foot) lengths of 300 ohm twin-lead TV antenna cable. The 3 antennas point in different directions. I was surprised to receive even more stations than I had hoped for, a total of 34 counting the sub-channels, all with digital quality. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=390745#390745 ________________________________ Message 12 ____________________________________ Time: 08:18:57 PM PST US Subject: AeroElectric-List: Re: Fwd: Iron-Constantan oil temp gauge From: "nuckollsr" Gee Dave. if you'd been sitting out with the rest of the class last time I was there . . . seriously tho . . . that was some time ago. Thermocouples are a unique kind of voltage source with a very low source impedance. I.e. the source impedance is equal to that of the wires which make up the thermocouple. In the present case, we're talking about type-K (iron-constantan) wire-couple. See: www.aeroelectric.com/articles/excerpt.pdf Those readings sound like resistances from the instrument end of one wire to the plug washer . . . If you measured beween the two wires at the instrument end, you would get 10 ohms . . . in the ball park for a properly working thermocouple. To make ACCURATE low resistance measurements you need something like the precision low resistance adapter on my website or some similar 4-wire ohmmeter. In any case, the slightly too-high reading you got is consistent with such lo-ohms readings at the ends of ordinary test leads. The thermocouple you have may be repairable. I've fixed a number of them that became 'open' right where the two wires crimp into the plug washer. I trim the wire back, strip ends, silver-solder together and then tack silver-solder the junction back onto the tang of the plug washer. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=390768#390768 ________________________________ Message 13 ____________________________________ Time: 10:42:49 PM PST US From: Dave Saylor Subject: Re: AeroElectric-List: Re: Fwd: Iron-Constantan oil temp gauge What can I say...the old neurons need the rust busted off just like an iron wire now and then. At least I didn't ask about parasitic junctions--that I remembered from your seminar, and I use that little tidbit every time we install the eight to 14 thermocouples on most of the engines we wire. The thermocouple that failed (the one in the picture) is a probe type that threads into the oil screen housing. Once I realized it was terminal, I took it apart. The iron wire was badly corroded and literally fell out of the probe body onto my workbench. It was covered with thick red rust. The other wire was firmly attached inside at the tip of the probe. I don't see any practical way to reattach an iron wire inside the tube of the probe so I'm open to suggestions. I'll probably try to find something similar to replace it. It's not surprising that the iron corroded. It got a hot/cold cycle on each engine run, and it was by no means sealed from the atmosphere. On every warming it drove out the air in the tube and on every cooldown it pulled in whatever was outside. It took 65 years, but it finally gave up the ghost. Dave Saylor 831-750-0284 CL On Thu, Dec 20, 2012 at 8:17 PM, nuckollsr wrote: > bob.nuckolls@aeroelectric.com> > > Gee Dave. if you'd been sitting out with the rest of the class last time I > was there . . . seriously tho . . . that was some time ago. > > Thermocouples are a unique kind of voltage source with a very low source > impedance. I.e. the source impedance is equal to that of the wires which > make up the thermocouple. In the present case, we're talking about type-K > (iron-constantan) wire-couple. See: > > www.aeroelectric.com/articles/excerpt.pdf > > Those readings sound like resistances from the instrument end of one wire > to the plug washer . . . If you measured beween the two wires at the > instrument end, you would get 10 ohms . . . in the ball park for a properly > working thermocouple. To make ACCURATE low resistance measurements you need > something like the precision low resistance adapter on my website or some > similar 4-wire ohmmeter. > > In any case, the slightly too-high reading you got is consistent with such > lo-ohms readings at the ends of ordinary test leads. > > > The thermocouple you have may be repairable. I've fixed a number of them > that became 'open' right where the two wires crimp into the plug washer. I > trim the wire back, strip ends, silver-solder together and then tack > silver-solder the junction back onto the tang of the plug washer. > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=390768#390768 > > ------------------------------------------------------------------------------------- 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.