---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Mon 11/17/03: 20 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:09 AM - Re: wire size for charging battery (j1j2h3@juno.com) 2. 02:29 AM - GPS Antenna (Neil Henderson) 3. 04:14 AM - Re: Cool schematic CAD program (F1Rocket@comcast.net) 4. 06:56 AM - Re: Crowbar OV protection (Scott Bilinski) 5. 07:23 AM - Re: Cool schematic CAD program (Eric M. Jones) 6. 07:48 AM - Re: wire size for charging battery (Robert L. Nuckolls, III) 7. 07:50 AM - Re: GPS Antenna (Robert L. Nuckolls, III) 8. 07:52 AM - Re: Re: Cool schematic CAD program (Steve Richard) 9. 08:21 AM - Alt Problem (John Danielson) 10. 08:44 AM - Re: Future replacement for Rotax (Robert L. Nuckolls, III) 11. 09:04 AM - Re: GPS Antenna (Dan Branstrom) 12. 09:41 AM - Re: Crowbar OV protection (Robert L. Nuckolls, III) 13. 10:24 AM - Re: Future replacement for Rotax rectifier/regulator ? (Gilles.Thesee) 14. 10:52 AM - Re: Crowbar OV protection (Scott Bilinski) 15. 11:12 AM - Fw: Future replacement for Rotax rectifier/regulator ? (Gilles.Thesee) 16. 01:20 PM - Re: Re: Cool schematic CAD program (Tony Babb) 17. 02:56 PM - Re: Alt Problem (Robert L. Nuckolls, III) 18. 04:09 PM - Bob, need info on microair com/xpdr (Rick Fogerson) 19. 05:08 PM - Re: Bob, need info on microair com/xpdr (Robert L. Nuckolls, III) 20. 07:14 PM - tach wiring Rotax 912S (Joa Harrison) ________________________________ Message 1 _____________________________________ Time: 02:09:28 AM PST US Subject: Re: AeroElectric-List: wire size for charging battery From: j1j2h3@juno.com --> AeroElectric-List message posted by: j1j2h3@juno.com One word of caution - if you do this, don't EVER connect another battery to this plug. If the battery on your plane is well-discharged, the other battery will try to provide a massive current flow and will smoke your connecting wire. Jim Hasper - RV-7 just starting empennage (setting up shop in Franklin, Tennessee) >--> AeroElectric-List message posted by: "Dan Branstrom" > > >Dave, >I believe that if you're just using the plug for charging, all you need is a >wire that matches the capacity of the charger (fused, of course). ________________________________ Message 2 _____________________________________ Time: 02:29:08 AM PST US From: "Neil Henderson" Subject: AeroElectric-List: GPS Antenna --> AeroElectric-List message posted by: "Neil Henderson" Listers I'm planning on mounting my GPS antenna on a firewall forward bracket just under the top surface of the cowl, rather than on the scuttle under the windscreen or externally. This seems to be a favoured place adopted by many builders. My question is will this location work satisfactorily with the standard antenna supplied with a Garmin 196 or is this only appropriate with a powered active unit. Thanks for your input. Neil Henderson RV9A nr Aylesbury UK ________________________________ Message 3 _____________________________________ Time: 04:14:25 AM PST US From: F1Rocket@comcast.net Subject: Re: AeroElectric-List: Cool schematic CAD program --> AeroElectric-List message posted by: F1Rocket@comcast.net Just this past week, I downloaded TurboCAD LE, which is free. I've found it easy to use and fully compatable with AutoCAD files. In about 4 hours, I built templates for all the electrical symbols on Bob's drawings and I'm in the process of putting together the wire book for my F1 Rocket. At some point, I'll have these posted on my web site. Randy #95 F1 Rocket http://mywebpages.home.comcast.net/ > --> AeroElectric-List message posted by: Dave Morris > > By the way, Bob, I was the guy that walked up to you at Sullivan and asked > if you knew of any free schematic drawing programs. I had IntelliCAD from > your CDROM and had tried to use it to draw up a schematic of my aircraft > system by modifying one of your Z diagrams. I never did like it very much > as it was not intuitive and had a long learning curve. So I have been on a > quest for a better CAD program for schematics ever since. I've looked at 3 > or 4 different free or "very cheap" programs and never was impressed with > any of them. > > But last week I found a really sweet program that immediately became my > favorite. It's called DesignWorks Lite, and can be downloaded from > http://www.designworks4.com with a fully functional version. The program > is $39.95 if you register it. (By the way, I have utterly no financial > interest in the program.. I just like it!) I tried it and was immediately > productive, without reading any help screens or manuals. It works the way > other Windows applications do, so it's very intuitive. The screen > background is light. There are scroll bars. It behaves the way a > schematic drawing program should, for instance, once you attach wires to a > component, you can move the component around and the wires stay > attached. It comes with a library of a bunch of symbols, and a symbol > designer that lets you create your own. The only drawback I've found is > that it does not use .DWG files, so you can't load the Z diagrams but have > to re-draw them yourself. > > If anybody wants an easy-to-learn schematic diagramming tool that is really > cheap and really good (but not compatible with Bob's CAD files), check out > DesignWorks Lite. > > Dave Morris > Dragonfly N55UP under construction > > > > > > ________________________________ Message 4 _____________________________________ Time: 06:56:20 AM PST US From: Scott Bilinski Subject: Re: AeroElectric-List: Crowbar OV protection --> AeroElectric-List message posted by: Scott Bilinski > Okay . . . yes, if you have a breaker-switch in the alternator field > circuit and it appears to open all by itself when you are switching > other things in the system, it may well be a nuisance trip of the > OV module. I'm working with another builder on the same issue. Actually in my case its only a problem when the battery has a VERY low charge (barely enought to start). Thats when I cannot turn on the ALT once engine is running. Turn on the ALT first and then start everythings fine. Turning anything on after the ALT is working, no problem. The only problem is turning the ALT on after the engine is running and the battery charge is very low. Scott Bilinski Eng dept 305 Phone (858) 657-2536 Pager (858) 502-5190 ________________________________ Message 5 _____________________________________ Time: 07:23:03 AM PST US From: "Eric M. Jones" Subject: AeroElectric-List: Re: Cool schematic CAD program --> AeroElectric-List message posted by: "Eric M. Jones" > If anybody wants an easy-to-learn schematic diagramming tool that is really > cheap and really good (but not compatible with Bob's CAD files), check out > DesignWorks Lite. > Dave Morris Not being able to read Bob's CAD files makes it a dead horse (regardless of how nice DWlite really is. Redrawing a schematic to make up for this is unreasonable. After a few programs and a few years everybody swears by their own spreadsheet, word processor, CAD program. In truth they are almost all very good, even miracles. I used to work for a company that had a really terrible clumsy and buggy and limited but HORRIBLY EXPENSIVE system (Cadra). The drafters (who knew nothing else) would have cut off their toes to keep it. They also insisted on paper SO BIG that I used a pair of binoculars to study drawings that easily would have fit on "A" size paper. Go to Tucows.com and see their giant list of CAD stuff. (The freeware FreeCAD 8.2 looks good if you want to study mechanical linkages.) Also check .... http://www.freecad.com/ lots of free stuff for CAD. My favorite is still DesignCad....if only for the reason when you call their free tech support you get fast tech help instantly. The line is never busy because the program is so easy to use. It's very much like AutoCAD but $3000 cheaper. It does 2D or 3D at the push of a button. Cool............... Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 Phone (508) 764-2072 Email: emjones@charter.net ________________________________ Message 6 _____________________________________ Time: 07:48:00 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: wire size for charging battery --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 03:48 AM 11/17/2003 -0800, you wrote: >--> AeroElectric-List message posted by: j1j2h3@juno.com > >One word of caution - if you do this, don't EVER connect another battery >to this plug. If the battery on your plane is well-discharged, the other >battery will try to provide a massive current flow and will smoke your >connecting wire. Which is why you put some form of circuit protection in ANY wire attached to ANY battery for ANY reason. Bob . . . ________________________________ Message 7 _____________________________________ Time: 07:50:09 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: GPS Antenna --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 10:27 AM 11/17/2003 +0000, you wrote: >--> AeroElectric-List message posted by: "Neil Henderson" > > >Listers > >I'm planning on mounting my GPS antenna on a firewall forward bracket just >under the top surface of the cowl, rather than on the scuttle under the >windscreen or externally. This seems to be a favoured place adopted by >many builders. My question is will this location work satisfactorily with >the standard antenna supplied with a Garmin 196 or is this only >appropriate with a powered active unit. Thanks for your input. Other folks on the list have personal experience with under-the-fiberglas- cowl location for GPS antennas and have uniformly reported good results. If you have a GPS receiver that's compatible with a powered antenna, I recommend it's use. They're cheap and small. In any case, experience has suggested that no antenna is at any particular disadvantage when installed on firewall and under the cowl. Bob . . . ________________________________ Message 8 _____________________________________ Time: 07:52:34 AM PST US From: "Steve Richard" Subject: RE: AeroElectric-List: Re: Cool schematic CAD program --> AeroElectric-List message posted by: "Steve Richard" DesignCad is not listed? Steve Richard steve@oasissolutions.com -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Eric M. Jones Subject: AeroElectric-List: Re: Cool schematic CAD program --> AeroElectric-List message posted by: "Eric M. Jones" > If anybody wants an easy-to-learn schematic diagramming tool that is really > cheap and really good (but not compatible with Bob's CAD files), check out > DesignWorks Lite. > Dave Morris Not being able to read Bob's CAD files makes it a dead horse (regardless of how nice DWlite really is. Redrawing a schematic to make up for this is unreasonable. After a few programs and a few years everybody swears by their own spreadsheet, word processor, CAD program. In truth they are almost all very good, even miracles. I used to work for a company that had a really terrible clumsy and buggy and limited but HORRIBLY EXPENSIVE system (Cadra). The drafters (who knew nothing else) would have cut off their toes to keep it. They also insisted on paper SO BIG that I used a pair of binoculars to study drawings that easily would have fit on "A" size paper. Go to Tucows.com and see their giant list of CAD stuff. (The freeware FreeCAD 8.2 looks good if you want to study mechanical linkages.) Also check .... http://www.freecad.com/ lots of free stuff for CAD. My favorite is still DesignCad....if only for the reason when you call their free tech support you get fast tech help instantly. The line is never busy because the program is so easy to use. It's very much like AutoCAD but $3000 cheaper. It does 2D or 3D at the push of a button. Cool............... Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 Phone (508) 764-2072 Email: emjones@charter.net ________________________________ Message 9 _____________________________________ Time: 08:21:02 AM PST US From: "John Danielson" Subject: AeroElectric-List: Alt Problem --> AeroElectric-List message posted by: "John Danielson" I have a problem that showed up after 165 hours. I have a Cessna type master switch. I usually flick both switches on before starting the engine. Lately I have been blowing the alt. field fuse when starting. If I leave the alt. switch off, start the engine then turn the alt. switch on, everything is ok. Any ideas why this is happening? John L. Danielson 307-266-2524 johnd@wlcwyo.com WLC, Inc. ________________________________ Message 10 ____________________________________ Time: 08:44:17 AM PST US From: "Robert L. Nuckolls, III" rectifier/regulator ? Subject: Re: AeroElectric-List: Future replacement for Rotax rectifier/regulator ? --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" rectifier/regulator ? At 08:50 AM 11/17/2003 +0100, you wrote: >--> AeroElectric-List message posted by: > >Gilles > >What is the problem with the original rectifier/regulator from Rotax? The standard rectifier regulator supplied with Rotax 912/914 engines is, I believe, made by Ducati. Ducati makes a whole raft of ignition and power generation products for small engines where the largest markets are for all manner of recreational vehicles . . . a tiny portion of which is aircraft. If you do a websearch on ducati "voltage regulator" and rotax you get a bunch of hits. Far too many of those posted articles talk about making the Ducati part last with most of the "fixes" going to keeping the part cool. My experience with Ducati parts suggests poor attention to design with respect to keeping internal parts of the regulator within their best operating temperature range. B&C's "heavy duty" regulator was nothing more that the standard circuit with robust, well heat-sinked parts. Do some research on the web and I think you'll get a sense of how much trouble folks are having with what should be a no-brainer. It would be a step forward to simply improve the thermal design of the current design. If I understand what Gilles' friend is attempting, we should be able to replace high-voltage- drop rectifiers with low-voltage-drop power field effect transistors. It's a much more complicated design but promises to offer much higher efficiency -AND- ultimately higher current carrying capacity. 18-20A is pushing the practical limits for the current design. Bob . . . ________________________________ Message 11 ____________________________________ Time: 09:04:23 AM PST US From: "Dan Branstrom" Subject: Re: AeroElectric-List: GPS Antenna --> AeroElectric-List message posted by: "Dan Branstrom" See the latest Kitplanes article on GPS antennas by Jim Weir on coverings of GPS antennas and ground planes. Dan Branstrom ----- Original Message ----- From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: GPS Antenna > --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > > At 10:27 AM 11/17/2003 +0000, you wrote: > >--> AeroElectric-List message posted by: "Neil Henderson" > > > > > >Listers > > > >I'm planning on mounting my GPS antenna on a firewall forward bracket just > >under the top surface of the cowl, rather than on the scuttle under the > >windscreen or externally. This seems to be a favoured place adopted by > >many builders. My question is will this location work satisfactorily with > >the standard antenna supplied with a Garmin 196 or is this only > >appropriate with a powered active unit. Thanks for your input. > > Other folks on the list have personal experience with under-the-fiberglas- > cowl location for GPS antennas and have uniformly reported good results. > If you have a GPS receiver that's compatible with a powered antenna, > I recommend it's use. They're cheap and small. In any case, experience > has suggested that no antenna is at any particular disadvantage when > installed on firewall and under the cowl. > > Bob . . . > > ________________________________ Message 12 ____________________________________ Time: 09:41:15 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Crowbar OV protection --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 06:55 AM 11/17/2003 -0800, you wrote: >--> AeroElectric-List message posted by: Scott Bilinski > > > > Okay . . . yes, if you have a breaker-switch in the alternator field > > circuit and it appears to open all by itself when you are switching > > other things in the system, it may well be a nuisance trip of the > > OV module. I'm working with another builder on the same issue. > >Actually in my case its only a problem when the battery has a VERY low >charge (barely enought to start). Thats when I cannot turn on the ALT once >engine is running. Turn on the ALT first and then start everythings fine. >Turning anything on after the ALT is working, no problem. The only problem >is turning the ALT on after the engine is running and the battery charge is >very low. Okay, this suggests that either (1) your engine is VERY difficult to start and/or (2) your battery is in VERY sad shape. We've all seen airplanes cranking out on the ramp that take multiple attempts of 10 second cranking intervals to finally get the engine going . . . if at all. The starter and battery in all cranking systems are in a huge OVERLOAD mode with respect to how the rest of the vehicle's systems perform. Mr. Kettering was soundly ridiculed when he suggested it's okay to pull 5 hp from a 1 hp motor . . . for a few seconds. He introduced the idea of purposely flogging some poor motor to within an inch of its life. He demonstrated that it could be done repeatedly and with dependability as long as the flogging stayed within certain bounds. It sounds as if there's insufficient battery voltage left after cranking to get your alternator to come on line. This is probably not a fault of the alternator or regulator. The normal cranking scenario should require no more than a few percent of a battery's capacity leaving plenty of snort for things to come on line and a MINIMAL energy replacement task when the alternator clocks in on the job. Load and capacity testing of your battery is in order. Fine tuning of engine characteristics that make it hard to start is another useful activity. Bob . . . ________________________________ Message 13 ____________________________________ Time: 10:24:34 AM PST US From: "Gilles.Thesee" Subject: Re: AeroElectric-List: Future replacement for Rotax rectifier/regulator ? --> AeroElectric-List message posted by: "Gilles.Thesee" > > The standard rectifier regulator supplied with Rotax 912/914 > engines is, I believe, made by Ducati. Ducati makes a whole > raft of ignition and power generation products for small engines > where the largest markets are for all manner of recreational > vehicles . . . a tiny portion of which is aircraft. Hi all, For those interested I found the website of the folks from "Ducati Energia". Italian speakers only. Last summer I was able to download the full alternator & rectifier pdf catalog, featuring the Rotax assembly. www.sgr-it.com FWIW Regards, Gilles ________________________________ Message 14 ____________________________________ Time: 10:52:12 AM PST US From: Scott Bilinski Subject: Re: AeroElectric-List: Crowbar OV protection --> AeroElectric-List message posted by: Scott Bilinski "Load and capacity testing of your battery is in order. Fine tuning of engine characteristics that make it hard to start is another useful activity." Battery is just fine, its the person trying to start the plane that needs help with the new systems.......Something about turning the fuel on or another. ________________________________ Message 15 ____________________________________ Time: 11:12:31 AM PST US From: "Gilles.Thesee" Subject: Fw: AeroElectric-List: Future replacement for Rotax rectifier/regulator ? --> AeroElectric-List message posted by: "Gilles.Thesee" Sorry, my first message got bounced. Gilles ----- Message d'origine ----- De : "Gilles.Thesee" : Envoy : lundi 17 novembre 2003 09:56 Objet : Re: AeroElectric-List: Future replacement for Rotax rectifier/regulator ? > > . If he'd like to collaborate, I'll offer a sounding > > board for ideas and hawk the product for him here on the AEC site if > > the result is suitably impressive. > > > > Bob . . . > > Hi Bob, > > I forwarded your collaboration offer to that smart fellow. At the moment > he's developping a light EFIS system for ultralights with some of his > students. The demonstrator system is already fairly impressive, though I > know there's a lot of development work before issuing an airworthy version. > > Thanks, > Gilles > > ________________________________ Message 16 ____________________________________ Time: 01:20:51 PM PST US From: "Tony Babb" Subject: Re: AeroElectric-List: Re: Cool schematic CAD program --> AeroElectric-List message posted by: "Tony Babb" Bob, Provides copies of several free CAD programs on his CD, which you can also download from his site if you have a broadband connection - or a dialup and lots of time !! ----- Original Message ----- From: "Eric M. Jones" Subject: AeroElectric-List: Re: Cool schematic CAD program > --> AeroElectric-List message posted by: "Eric M. Jones" > > > If anybody wants an easy-to-learn schematic diagramming tool that is > really > > cheap and really good (but not compatible with Bob's CAD files), check out > > DesignWorks Lite. > > Dave Morris > > Not being able to read Bob's CAD files makes it a dead horse (regardless > of how nice DWlite really is. Redrawing a schematic to make up for this is > unreasonable. After a few programs and a few years everybody swears by their > own spreadsheet, word processor, CAD program. In truth they are almost all > very good, even miracles. I used to work for a company that had a really > terrible clumsy and buggy and limited but HORRIBLY EXPENSIVE system (Cadra). > The drafters (who knew nothing else) would have cut off their toes to keep > it. They also insisted on paper SO BIG that I used a pair of binoculars to > study drawings that easily would have fit on "A" size paper. > > Go to Tucows.com and see their giant list of CAD stuff. (The freeware > FreeCAD 8.2 looks good if you want to study mechanical linkages.) > > Also check .... http://www.freecad.com/ lots of free stuff for CAD. > > My favorite is still DesignCad....if only for the reason when you call their > free tech support you get fast tech help instantly. The line is never busy > because the program is so easy to use. It's very much like AutoCAD but $3000 > cheaper. It does 2D or 3D at the push of a button. Cool............... > > Regards, > Eric M. Jones > www.PerihelionDesign.com > 113 Brentwood Drive > Southbridge MA 01550-2705 > Phone (508) 764-2072 > Email: emjones@charter.net > > ________________________________ Message 17 ____________________________________ Time: 02:56:57 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Alt Problem --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 09:20 AM 11/17/2003 -0700, you wrote: >--> AeroElectric-List message posted by: "John Danielson" > >I have a problem that showed up after 165 hours. >I have a Cessna type master switch. I usually flick both switches on >before starting the engine. Lately I have been blowing the alt. field >fuse when starting. I presume you ave a crowbar ov protection module. Are you blowing a fuse or circuit breaker? It sounds as if something has changed in your airplane to create a condition that happens in a small number of situations were a crowbar system is installed. How old is your battery? >If I leave the alt. switch off, start the engine then turn the alt. >switch on, everything is ok. >Any ideas why this is happening? Not at the moment . . . but then, it's perfectly fine to leave the alternator off until after the engine is started. Do you have a diode around the coil of your starter contactor? Bob . . . ________________________________ Message 18 ____________________________________ Time: 04:09:31 PM PST US From: "Rick Fogerson" Subject: AeroElectric-List: Bob, need info on microair com/xpdr SMTPD_IN_RCVD --> AeroElectric-List message posted by: "Rick Fogerson" Hi Bob, I bought wiring harnesses from you some time back but just getting around to installing. I'm building an RV3 so no need for intercom or co-pilot stuff. No wiring diagram sent so I need to know what they connect to. Questions and confirmation Re MicroAir Xpdr: 1) black wire connected to pin 23 and therefor should go to ground. 2) yellow wire, connected to pin 24, and therefor should go to 12 volt power. 3) however, not sure what the following "free end" wires connect to: purple (pin 16, "external ident")? blue (pin 15, "external standby in)? blue coated coax wire? Questions Re MicroAir Radio: 1) I am only going to be using the following pins with the noted wires: pin 1, Microphone (small yellow) pin 2, Mic Ground (22 AWG white w black stripe) pin 7, PTT (small blue) pin 9, 12V (22 AWG yellow) pin 11, Ground (22 AWG black) pin 14, Head Phone (22 AWG white) What I don't understand is: 2) There is no white w black stripe wire coming out of the red tape (at the connector) so I don't know what wire goes to Mic Ground. 3) There is a blue coated coax wire coming out of the red tape and I don't know what that connects to? 4) Also, confirm that the PTT wire from pin 7 just connects to the pilot PTT button and the intercom selector switch is eliminated. Thanks for your help, Rick Fogerson ________________________________ Message 19 ____________________________________ Time: 05:08:54 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Bob, need info on microair com/xpdr --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 05:10 PM 11/17/2003 -0700, you wrote: >--> AeroElectric-List message posted by: "Rick Fogerson" > >Hi Bob, >I bought wiring harnesses from you some time back but just getting around >to installing. I'm building an RV3 so no need for intercom or co-pilot >stuff. No wiring diagram sent so I need to know what they connect to. > >Questions and confirmation Re MicroAir Xpdr: >1) black wire connected to pin 23 and therefor should go to ground. >2) yellow wire, connected to pin 24, and therefor should go to 12 volt power. >3) however, not sure what the following "free end" wires connect to: > purple (pin 16, "external ident")? > blue (pin 15, "external standby in)? > blue coated coax wire? See http://www.aeroelectric.com/Installation_Data/T2000-ACK350_Wiring.pdf Purple goes to optional remote ident button, leave unconnected if not used. Blue wire goes to optional remote standby/on switch, leave unconnected if not used. Blue jacket shielded wire is reply beep out that can optionally be routed to your audio distribution amplifier. I'm not sure as to the exact function of this feature, manual should be more helpful. >Questions Re MicroAir Radio: >1) I am only going to be using the following pins with the noted wires: > pin 1, Microphone (small yellow) > pin 2, Mic Ground (22 AWG white w black stripe) > pin 7, PTT (small blue) > pin 9, 12V (22 AWG yellow) > pin 11, Ground (22 AWG black) > pin 14, Head Phone (22 AWG white) >What I don't understand is: You should have received a copy of http://www.aeroelectric.com/Installation_Data/760VHF.pdf with the harness. If not, download it for more info. >2) There is no white w black stripe wire coming out of the red tape (at >the connector) so I don't know what wire goes to Mic Ground. Page 11 of the installation instructions show that pin 2 is attached to shields of the microphone and headset wires. Jacks are grounded back to the radio via the shields on both microphone and headset jacks as shown in diagram. >3) There is a blue coated coax wire coming out of the red tape and I don't >know what that connects to? That's the single conductor shielded wire for headset output >4) Also, confirm that the PTT wire from pin 7 just connects to the pilot >PTT button and the intercom selector switch is eliminated. No, if you want to use the intercom function you need either (1) a push-for-intercom button on each control stick as shown on page 11 or (2) a single toggle switch on panel to open the intercom function as shown on page 12. Bob . . . ________________________________ Message 20 ____________________________________ Time: 07:14:08 PM PST US From: Joa Harrison Subject: AeroElectric-List: tach wiring Rotax 912S --> AeroElectric-List message posted by: Joa Harrison When wiring the tach on the 912S is shielded wire needed going from the engine sender to the unit? Joa ---------------------------------