---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 09/21/09: 18 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:22 AM - Re: P-mag Internal Power Test (Andrew Butler) 2. 06:25 AM - Flightcom headset (luigit@freemail.it) 3. 06:25 AM - Re: Kitplanes article on solar power (Joe) 4. 07:15 AM - Re: P-mag Internal Power Test (Robert L. Nuckolls, III) 5. 07:22 AM - Dual Battery Dual Alternator Grounding (dsyvert) 6. 07:26 AM - Re: Re: Fixed connector on the Transponder Mounting Tray (Robert L. Nuckolls, III) 7. 07:29 AM - Re: Flightcom headset (Robert L. Nuckolls, III) 8. 08:33 AM - Re: Dual Battery Dual Alternator Grounding (Robert L. Nuckolls, III) 9. 10:53 AM - Re: Bus Voltage (Speedy11@aol.com) 10. 01:09 PM - Re: Van's gauges (Robert L. Nuckolls, III) 11. 01:37 PM - Re: Re: Filter for Hand held devices (Robert L. Nuckolls, III) 12. 02:22 PM - Re: Re: Filter for Hand held devices (Ian) 13. 03:45 PM - Re: Van's gauges (John Danielson) 14. 07:21 PM - Aerobatics and Instrument Damage (PeterHunt1@aol.com) 15. 08:19 PM - Re: Aerobatics and Instrument Damage (BobsV35B@aol.com) 16. 09:32 PM - Re: Re: Filter for Hand held devices (Robert L. Nuckolls, III) 17. 10:17 PM - Transmit problem on both comm radios. (DEAN PSIROPOULOS) 18. 11:16 PM - Re: Re: Filter for Hand held devices (Jay Hyde) ________________________________ Message 1 _____________________________________ Time: 05:22:20 AM PST US From: Andrew Butler Subject: Re: AeroElectric-List: P-mag Internal Power Test Hi Mike, Here is some additional info. I got from Emagair directly last year when researching the units. I personally have wired up according to Z13, with two switches for each unit, p-lead and power. I don't have CBs for the circuits, rather fuses. Regards, Andrew. ------------------------------------------------------------------------------------------------------------------- From: info@emagair.com [mailto:info@emagair.com] Sent: 09 May 2008 16:57 Subject: RE: Startup Checks Andrew: When an ignition is first powered up it has to wake up, load the operating code, track engine position, determine when the next spark even needs to happen, and finally trigger that spark event. If you power up while the engine is running all this has to happen very quickly. Since P models make their own power (as long as the engine is running), you cannot shut down the processor. You can turn both the p-lead and the 12 supply OFF and it will still be "awake" doing its business as usual, waiting to resume firing as soon as the p-lead is ungrounded. With E models, however, you can power them OFF when running, and the ignition (truly) will go dark - still no problem. Powering the E model OFF is not the issue. It's when you 1) power an E model ON (while the engine is running) and 2) with the p-lead ungrounded that you are asking it to instantaneously wake up and start firing as described above. The condition can be avoided (if encountered) by making sure the p-lead is grounded (OFF) before powering (12 volt) ON an E model ignition while the engine is running. Even so, if this happens, we aren't predicting disaster. It will probably resume operation just fine, but there is no reason to do it in the first place - that's all. I don't recall any customers (yet) in Ireland - congratulations, you'll be number 1. Kindest Regards, Brad Dement E-MAG Ignitions 2014 Greg Street Box 112 Azle, Texas 76020 (817) 444-5310 From: Butler, Andrew [mailto:andrew.butler@nuigalway.ie] Sent: Friday, May 09, 2008 10:29 AM Subject: RE: Startup Checks Thanks very much Brad. What is the logic behind not switching off power to an E-MAG while the engine is running? I am assuming that switching off power is okay, that it is switching power back on while the engine is turning that is the problem. What exactly is the event sequence associated with switching on power while the engine is turning that is problematic? Why is it problematic to turn power on while the P-MAG is live i.e ungrounded? I am not installing a rotary key switch, rather an individual power switch for each ignition. It appears that I will need a two position switch that allows me to control access to power and ground individually. Cheers, Andrew. RV71700 Galway, Ireland. From: info@emagair.com [mailto:info@emagair.com] Sent: 08 May 2008 17:07 Subject: RE: Startup Checks Hi Andrew: Thanks for considering us for your project. The ignition check for E-MAG ignitions is very similar to that of magnetos. You'll do your regular L/R (p-lead) check to make sure both ignitions operate. The only difference is that for each P model ignition you have installed (one or both) you'll add one additional sequence. While switched to the individual P model(s), simply turn OFF the 12 volt power that feeds that ignition for a few seconds to verify the engine continues to run. If the engine runs, the internal alternator is operating. If the engine quits, the alternator is not working. The engine speed should be 1000 rpm or greater when you do this check. There is no need to do this test with an E model as they don't have an alternator. The L/R test is a p-lead (ON/OFF) test applicable to both E and P models. The 12 power (ON/OFF) test is applicable to P models only, and we discourage doing it with E models, so the FAQ you refer to is not in conflict with the pre-flight ignition tests. The Installation and Operating Guide also has some recommendations on starting with our equipment - see Downloads page on our web site. Don't hesitate to call or drop us a note if you have any other questions. Kindest Regards, Brad Dement E-MAG Ignitions 2014 Greg Street Box 112 Azle, Texas 76020 (817) 444-5310 ------------------------------------------------------------------------------------------------------- ----- Original Message ----- From: "Robert L. Nuckolls, III" Sent: Monday, 21 September, 2009 2:11:36 AM GMT +00:00 GMT Britain, Ireland, Portugal Subject: Re: AeroElectric-List: P-mag Internal Power Test At 03:45 PM 9/20/2009, you wrote: > >I am getting my wiring started and have a question on how some of >you with P-Mags wired your systems. There are two tests for th >P-Mag as I understand things. One is just like a traditional >magneto check, you turn off (ground the p-lead) and check for mag >drop. The other check for a P-Mag is to turn off the 12v power to >the P-Mag to check that the internal alternator keeps the magneto >running. The check of the internal alternator does not seem like >something that needs to be check each flight. I am considering just >pulling the CB for each P-Mag to make this check rather than wiring >a switch to serve this purpose. > >What have others done with regard to this, I don't want to use a >switched breaker, I will just add the switch if it is required. My >thinking is to just pull the breaker. We pull breaker on the B-767 >at the end of each flight to turn some equipment off while the plane >sits between flights, so I don't think there is an issue of waring >out a breaker. Thanks for any pointers. What you've proposed is consistent with Emagair's recommendations. In fact, Figure Z13/8 was crafted with a similar philosophy. http://www.aeroelectric.com/PPS/Adobe_Architecture_Pdfs/Z13-8Q.pdf Note that with ship's power taken through a fuse from the main bus, the internal power source integrity can be verified occasionally by checking engine operations on the p-mag while the main bus is down. Easy to do under comfortable conditions and only occasionally. Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 2 _____________________________________ Time: 06:25:06 AM PST US From: luigit@freemail.it Subject: AeroElectric-List: Flightcom headset --- MIME Errors - No Plain-Text Section Found --- A message with no text/plain MIME section was received. The entire body of the message was removed. Please resend the email using Plain Text formatting. HOTMAIL is notorious for only including an HTML section in their client's default configuration. If you're using HOTMAIL, please see your email application's settings and switch to a default mail option that uses "Plain Text". --- MIME Errors No Plain-Text Section Found --- ________________________________ Message 3 _____________________________________ Time: 06:25:29 AM PST US From: "Joe" Subject: Re: AeroElectric-List: Kitplanes article on solar power Carlos, Try this link: http://www.kitplanes.com/issues/pdfs/0107-6566.pdf Jim Weir's website: http://www.rst-engr.com/rst/contact_us.html I will send an email to you with a scanned copy of the schematic. Joe Michigan USA ________________________________ Message 4 _____________________________________ Time: 07:15:52 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: P-mag Internal Power Test At 06:47 AM 9/21/2009, you wrote: > > >Hi Mike, > >Here is some additional info. I got from Emagair directly last year >when researching the units. I personally have wired up according to >Z13, with two switches for each unit, p-lead and power. I don't have >CBs for the circuits, rather fuses. > >Regards, Andrew. Thanks for that expansion Andrew. I had a similar dissertation from the guys at Emagair but couldn't lay my hands on it last night. Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 5 _____________________________________ Time: 07:22:12 AM PST US Subject: AeroElectric-List: Dual Battery Dual Alternator Grounding From: "dsyvert" I have two #2 AWG cables running from the back of my RV-10 to the firewall. My question is if I put in two batteries and two alternators, where do I ground each one. Van's plans show the grounding at the behind the baggage bulk head. Could both batteries be grounded there to a common ground? I intended to use the second cable as a ground from the battery to the firewall, but Van's shows it to be grounded to the battery box. Sorry if this has already been addressed dsyvert Read this topic online here: http://forums.matronics.com/viewtopic.php?p=264118#264118 ________________________________ Message 6 _____________________________________ Time: 07:26:14 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Fixed connector on the Transponder Mounting Tray >How does a BNC connector hook up with these connectors, like the end >on a TED aerial??? > These connectors accept a prepared end of the antenna's feed-line coax. They are solder joints for both the center conductor and shield. If you want to break that feedline with a connector adjacent to the radio, then the segment that comes off the slip-connector is simply shortened to a pigtail of the desired length which is then terminated in a cable-female . . . http://www.aeroelectric.com/Pictures/Connectors/Coax/BNC_Cable_Female_2.jpg Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 7 _____________________________________ Time: 07:29:26 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Flightcom headset At 07:58 AM 9/21/2009, you wrote: > > > >Not usual for me this kind of assistance. > >Thank you Becky and thank you Flightcom. > >A very good headset and an excellent service. > >Luigi Your observations agree with my own. The few times I've had occasion to communicate with Flightcom, their willingness to share has been exemplary . . . and I'm not even a customer! Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 8 _____________________________________ Time: 08:33:08 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Dual Battery Dual Alternator Grounding At 09:20 AM 9/21/2009, you wrote: > >I have two #2 AWG cables running from the back of my RV-10 to the >firewall. My question is if I put in two batteries and two >alternators, where do I ground each one. Van's plans show the >grounding at the behind the baggage bulk head. Could both batteries >be grounded there to a common ground? I intended to use the second >cable as a ground from the battery to the firewall, but Van's shows >it to be grounded to the battery box. Independent grounds to structure will be consistent with design goals for elimination of single points of failure. See . . . http://aeroelectric.com/Pictures/Batteries/Battery_Install_OBrien_2.jpg do this for EACH battery. Also, 4AWG welding cable jumpers from battery(+) to contactor and battery(-) to ground are a good idea to minimize mechanical stress on terminals. Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 9 _____________________________________ Time: 10:53:00 AM PST US From: Speedy11@aol.com Subject: AeroElectric-List: Re: Bus Voltage Joe, I took careful notice of the bus voltage yesterday as I loaded up the bus and you've brought up a good point. At an 8 amp load, the bus voltage was 13.5. At 29 amps it dropped to 13.2 and stayed there until I reduced the load. So, I must have too small a wire from the alternator to the bus. I'll consider changing it. Thanks, Stan Sutterfield Joe, Thanks for your comment. I have taken notice of the voltage during light and heaviest loads and it remains steady at 13.5. The light loading was about 3 Amps and heavy was about 32A (everything on). So, I'll take readings as Bob suggested and see what I find. Stan Stan, A good test is to compare the bus voltage with light loads to the bus voltage with heavy loads. If there is a big difference, then there is a lot of resistance in the circuit, possibly from too small wire or from bad connections. Joe ________________________________ Message 10 ____________________________________ Time: 01:09:58 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Van's gauges At 12:46 PM 9/14/2009, you wrote: >In 420 house over three plus years a number of Van's gauges have >failed (fuel quantity, volts, amps, oil pressure). Now I must >install the third volt meter. I like the look of Van's gauges and >the fact that they match, but don't like the failure rate. What >have your experiences been? > >Pete in Clearwater >RV-6 - Reserve Grand Champion, S 'n F 2006 and other awards > >---------- Peter, Sorry to hear about this . . . I've got a Van's ammeter on the bench which I disassembled to look at. Hand- assembled, thru-hole components (not necessarily a 'bad' thing, especially in TC aviation!). However, the ammeter proved to be exceptionally vulnerable to radio-frequency fields (hand held). It's a line-item on my things-to-do list to see what sort of filter/shielding would reduce the effects to acceptable levels. My discovery raises a perplexing question . . . How much of the technology and design goals for the ammeter are common to the rest of the product line? Of course, my question only goes to system integration . . . a question which is moot if the critters have an unacceptable failure rate. Your question is the first I've heard of it. I'd be pleased to have updates from the rest of List membership. P.S. Sorry we didn't get together while attending to Dr. Dee at the convention last winter. It was an interesting and opportunity-packed event. I don't think we got out of the hotel more than a half dozen trips to local eateries! Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 11 ____________________________________ Time: 01:37:32 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Re: Filter for Hand held devices At 08:11 AM 9/14/2009, you wrote: > >I think that I do need one; I am using a cigarette lighter type connection >to power an Ipod power supply. When I connect this to the Ipod no noise is >heard, but when I connect the Ipod to the radio/ intercom system I >immediately get a high pitched noise in the earphones. Okay, 'high pitched' is not alternator noise. It MIGHT be an artifact of the dc/dc converter in your ipod power adapter. Try first to power the Ipod internally without the adapter. Does the noise go away? Try powering the adapter fromits own 12 battery pack NOT connected to the a/c in any way. A couple of el-cheeso 6v lantern batteries in series a good diagnostic supply. > I separated the >power and signal leads and the noise stayed. I moved the power supply of >the cigarette/ Ipod charger directly to the battery and the noise stayed. I >will still try a twisted pair on the power supply to the radio/intercom but >it seems to me that the noise is generated by the Ipod charger so I thought >that a filter might do the trick. Perhaps even a ferrite bead on the >positive in to the radio will work. > >The only other thing that I can think of is that the loop formed by the >plug->Ipod charger->Ipod audio out->radio/intercom is somehow causing the >problem; but how does one get rid of that loop- its intrinsic to the music >input? It's most likely to be a ground loop issue which will be re-enforced or denied by the above experiments. In any case, it's almost a certainty that filtering is not solution for root cause. We may have to incorporate an isolation transformer where audio from your Ipod goes to one winding and audio to the ship's system is taken from the other winding. See: http://www.radioshack.com/product/index.jsp?productId=2103994 Bob . . . ________________________________ Message 12 ____________________________________ Time: 02:22:19 PM PST US Subject: RE: AeroElectric-List: Re: Filter for Hand held devices From: Ian Just for information of those on the list, I recently had a faulty 12V charger on an AV8OR. The manufacturer willingly changed it. The symptoms were more your conventional white noise type static, like a very weak radio signal - there when charging the AV8OR, gone when not. It interfered with radio reception in the car and in the aircraft. I'm not proposing it as the cause of the IPOD problem below, just a useful data point. Faulty chargers do indeed seem capable of generating interference but not, in my case, a high pitched noise. Ian Brown Bromont, Quebec > >The only other thing that I can think of is that the loop formed by the > >plug->Ipod charger->Ipod audio out->radio/intercom is somehow causing the > >problem; but how does one get rid of that loop- its intrinsic to the music > >input? > > It's most likely to be a ground loop issue which will be > re-enforced or denied by the above experiments. > > In any case, it's almost a certainty that filtering > is not solution for root cause. > > We may have to incorporate an isolation transformer > where audio from your Ipod goes to one winding and > audio to the ship's system is taken from the other > winding. See: ________________________________ Message 13 ____________________________________ Time: 03:45:44 PM PST US From: John Danielson Subject: RE: AeroElectric-List: Van's gauges I also used Van's Gauges. I had trouble with the ammeter also. Never did get it to work quite right. It worked OK until you transmitted. The oil pressure gauge only worked when the engine oil was cold. After the temperature climbed to normal temps, the pressure would drop to 20 of 30 ps i, sometimes to 0. The rest of my Vans gauges (fuel quant, fuel pressure, tachometer, volt met er, manifold pressure) worked great after 300 hrs. John Danielson ________________________________ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectr ic-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Monday, September 21, 2009 2:08 PM Subject: Re: AeroElectric-List: Van's gauges At 12:46 PM 9/14/2009, you wrote: In 420 house over three plus years a number of Van's gauges have failed (fu el quantity, volts, amps, oil pressure). Now I must install the third volt meter. I like the look of Van's gauges and the fact that they match, but don't like the failure rate. What have your experiences been? Pete in Clearwater RV-6 - Reserve Grand Champion, S 'n F 2006 and other awards ________________________________ Peter, Sorry to hear about this . . . I've got a Van's ammeter on the bench which I disassembled to look at. Hand- assembled, thru-hole components (not necessarily a 'bad' thing, especially in TC aviation!). However, the ammeter proved to be exceptionally vulnerable to radio-frequency fields (hand held). It's a line-item on my things-to-do list to see what sort of filter/shielding would reduce the effects to acceptable levels. My discovery raises a perplexing question . . . How much of the technology and design goals for the ammeter are common to the rest of the product line? Of course, my question only goes to system integration . . . a question which is moot if the critters have an unacceptable failure rate. Your question is the first I've heard of it. I'd be pleased to have updates from the rest of List membership. P.S. Sorry we didn't get together while attending to Dr. Dee at the convention last winter. It was an interesting and opportunity-packed event. I don't think we got out of the hotel more than a half dozen trips to local eateries! Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 14 ____________________________________ Time: 07:21:23 PM PST US From: PeterHunt1@aol.com Subject: AeroElectric-List: Aerobatics and Instrument Damage I have completed some excellent Unusual Attitude training in a Cap-10 which included loops, rolls and spins and will soon complete additional aerobatic training. Then I would like to try some of these aerobatics maneuvers in my RV-6. However, I am a little concern that the gyro tumbling and/or G forces of aerobatics may hurt my instruments. I have an AI, HSI and S-TEC autopilot all containing electric gyros and would hate to damage them. What has been your experience with aerobatics and instrument damage? Should I be concerned about this? Pete in Clearwater RV-6, Day/night IFR, Reserve Grand Champion S 'n F ________________________________ Message 15 ____________________________________ Time: 08:19:01 PM PST US From: BobsV35B@aol.com Subject: Re: AeroElectric-List: Aerobatics and Instrument Damage Good Evening Peter, As Always, It All Depends! Your S-Tec uses the canted gyro in the Turn Coordinator for it's sensing device. That gyro will not be harmed by aerobatics. The attitude and heading gyros MAY be damaged! There are many different designs and your best bet is to check with the manufacturer of your instrumentation. Some of the newer instruments are suitable for aerobatic use. There were some fully aerobatic artificial horizons built about fifty years ago, but the pitch indication was just the opposite of what is standard today. There are a few older gyros that allow the gyros to be caged, but that is not a real good idea. It can keep the gyro from banging the stops, but the bearings will still incur abnormal wear. The best bet is to have a removable gyro panel to be used when not flying aerobatics. A few of the professional aerobatic pilots have made such a set up to save wear and tear during violent aerobatic flight. One more comment if you don't mind. The turn Coordinator (as is used by S-Tec for sensing) is an abominable instrument in that it never tells the truth. For use during aerobatics, I much prefer a standard old fashioned Turn needle combined with an inclinometer Ball. The classic needle and ball. It is the most reliable directional instrument you can buy and it can be used for spin recovery as well as unusual attitude recovery. A turn coordinator can provide confusing and counterproductive indications during a spin recovery. However, neither the T&B nor the TC will be damaged by doing such maneuvers. Many of the modern glass panels use solid state "gyros" that are not damaged by aerobatics, but some will lose proper sensing. Any help at all? Happy Skies, Old Bob AKA Bob Siegfried Downers Grove, Illinois LL22 Stearman N3977A In a message dated 9/21/2009 9:22:37 P.M. Central Daylight Time, PeterHunt1@aol.com writes: I have completed some excellent Unusual Attitude training in a Cap-10 which included loops, rolls and spins and will soon complete additional aerobatic training. Then I would like to try some of these aerobatics maneuvers in my RV-6. However, I am a little concern that the gyro tumbling and/or G forces of aerobatics may hurt my instruments. I have an AI, HSI and S-TEC autopilot all containing electric gyros and would hate to damage them. What has been your experience with aerobatics and instrument damage? Should I be concerned about this? Pete in Clearwater RV-6, Day/night IFR, Reserve Grand Champion S 'n F (http://www.matronics.com/Navigator?AeroElectric-List) (http://www.matronics.com/contribution) ________________________________ Message 16 ____________________________________ Time: 09:32:35 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Re: Filter for Hand held devices At 04:18 PM 9/21/2009, you wrote: >Just for information of those on the list, I recently had a faulty >12V charger on an AV8OR. The manufacturer willingly changed >it. The symptoms were more your conventional white noise type >static, like a very weak radio signal - there when charging the >AV8OR, gone when not. It interfered with radio reception in the >car and in the aircraft. I'm not proposing it as the cause of the >IPOD problem below, just a useful data point. Faulty chargers do >indeed seem capable of generating interference but not, in my case, >a high pitched noise. The modern DC/DC converter technology has become smaller and more efficient as the components became available to operate at high and higher frequencies. The DC to DC converters that we used in the Cessna Nav/Com 300 in 1965 ran at about 1 Khz . . . and had relatively benign RF interference potential. That little nugget of electronics that exists in the cigar lighter plug on your ipod or cell phone charger probably operates at 1000 to 2000 times higher frequency. These guys are much more likely to become noise emitters in the AM radio band. I've had several devices that I had to throw away and substitute another brand. Bob . . . Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 17 ____________________________________ Time: 10:17:02 PM PST US From: "DEAN PSIROPOULOS" Subject: AeroElectric-List: Transmit problem on both comm radios. Hi all: Maybe you can help with my transmit problems. I have a UPS Aviation Technologies (now Garmin AT) radio stack with SL-30 Nav Comm, GX-65 GPS/Comm, SL-70 transponder and SL-10MS audio panel (actually a PS-6000 with UPS AT nameplate). I checked out everything according to the installation manuals while the airplane was sitting on the ramp and the engine NOT running. Now that I've been flying a lot, I'm getting a crackling in the sidetone and when I look at the "TX" light on the radio it's flickering as if someone were pulsing the press-to-talk switch 4-5 times per second, even though I'm holding the PTT down tight. This happens on both radios and people in the pattern say I'm breaking up and garbled. I've tried several things looking for a solution, they are: 1) Turn down the MIC gains on both radios (in steps, a little at a time, over several flights). In the end I had them turned down so much I couldn't get a side tone in the earphones and suspect no-one could hear me at all. 2) I tried a couple different headsets (inexpensive non ANR types, Sigtronics and Pilot Avionics units, both around 15 years old but well taken care of and worked just fine in the Cessnas I used to rent). No joy. 3) I tried both headsets with and without foam muffs over the microphones. No difference that I could tell with or without the muffs. 4) Placed ferrite beads over both coax lines running to the transmit antennas (about 3/4 of the way down to the antennas, don't have access to the base of the antennas right now, but will when I remove the floor panels for annual inspection). No help! 5) Shut off the field in my B&C LR-60 alternator (with external regulator) to operate on battery only. No change (I'm using forest of ground tabs ala AEC philosophy and I'm NOT getting alternator noise in the reception of either radio so I didn't expect this to help but it was easy to test). 6)Since I used fine (24 gauge 5 condutor MAC servo cable, no shielding) wire to take the PTT signal from the PTT on the control stick to the pilots mic jack, I thought maybe that was causing a problem so I tried using the passengers PTT (wired with 22 ga shielded tefzel) instead of the pilots. No change. 7) The audio panel has a built in fail-safe feature that routes the PTT and mic/earphone signals direct to the number 1 NAV/COM in the event of audio panel failure. I shut off the audio panel and tried that. The NAV/COMM TX light comes on but still flickers and is crackly so it's not that. I of course could not test the #2 radio this way but would expect it to be the same. Transmit antenna location is under the belly of the airplane (all metal RV-6A). Two Comant bent whips about 40 inches apart just aft of the wing spar. The GPS portion of the GX-60 and VOR/ILS portion of the SL-30 work just fine. Comm reception on both radios is loud and clear (at least I can hear people in the pattern even if I can't talk to them). When I originally ran through the installation checkout I left the settings on the radios at the factory recommended (transmit worked fine so I left the settings alone) and have been making changes to the Mic gains only. These are computer controlled radios so I'm wondering if I need to adjust any other parameters such as squelch (no pots to control squelch like the old days) after making the Mic gain adjustments. Could the two be somehow related through logic in the computer program that runs the radios? I'm really stumped, any suggestions? Any UPS AT radio stack users have this problem? How did you fix it? Should I run through the installation checkout with the engine running so as to have more noise impinging on the microphone while making adjustments? Don't like the idea of head down in the cockpit with engine running but I can tie down the airplane while doing the checks (I'm talking ground running here not trying to make adjustments in flight)! Thanks for the help. Dean Psiropoulos RV-6A N197DM Flying and tweeking. ________________________________ Message 18 ____________________________________ Time: 11:16:10 PM PST US From: "Jay Hyde" Subject: RE: AeroElectric-List: Re: Filter for Hand held devices Thanks Bob, That does make sense; I had isolated it to the dc/dc converter in the same manner that you suggest here- by powering the device internally. I knew that it wasn't alternator noise since I was running off the a/c battery only. I then found out that the same noise has presented itself on another installation that I did, so it couldn't be installation specific. There the owner simply let the Ipod charge up and then disconnected it from the system and played the music into the audio system using the Ipod internal battery. I'll try and get an isolation transformer here and see what effect that has; it is simply a transformer with a 1:1 winding ratio? Jay -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: 21 September 2009 10:35 PM Subject: RE: AeroElectric-List: Re: Filter for Hand held devices At 08:11 AM 9/14/2009, you wrote: > >I think that I do need one; I am using a cigarette lighter type connection >to power an Ipod power supply. When I connect this to the Ipod no noise is >heard, but when I connect the Ipod to the radio/ intercom system I >immediately get a high pitched noise in the earphones. Okay, 'high pitched' is not alternator noise. It MIGHT be an artifact of the dc/dc converter in your ipod power adapter. Try first to power the Ipod internally without the adapter. Does the noise go away? Try powering the adapter fromits own 12 battery pack NOT connected to the a/c in any way. A couple of el-cheeso 6v lantern batteries in series a good diagnostic supply. > I separated the >power and signal leads and the noise stayed. I moved the power supply of >the cigarette/ Ipod charger directly to the battery and the noise stayed. I >will still try a twisted pair on the power supply to the radio/intercom but >it seems to me that the noise is generated by the Ipod charger so I thought >that a filter might do the trick. Perhaps even a ferrite bead on the >positive in to the radio will work. > >The only other thing that I can think of is that the loop formed by the >plug->Ipod charger->Ipod audio out->radio/intercom is somehow causing the >problem; but how does one get rid of that loop- its intrinsic to the music >input? It's most likely to be a ground loop issue which will be re-enforced or denied by the above experiments. In any case, it's almost a certainty that filtering is not solution for root cause. We may have to incorporate an isolation transformer where audio from your Ipod goes to one winding and audio to the ship's system is taken from the other winding. See: http://www.radioshack.com/product/index.jsp?productId=2103994 Bob . . . ------------------------------------------------------------------------------------- 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.