---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 11/26/15: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:13 AM - Re: Re: Troubleshooting radio whine/noise on C essna 182P (Jan) 2. 06:52 AM - Re: Rotax ignition wiring (user9253) 3. 06:52 AM - Re: Troubleshooting radio whine/noise on C essna 182P (user9253) ________________________________ Message 1 _____________________________________ Time: 06:13:39 AM PST US Subject: Re: AeroElectric-List: Re: Troubleshooting radio whine/noise on C essna 182P From: Jan Will be interesting to hear what the final outcome will be on your "noise" problem. Regarding the isolation of the microphone - I am sure someone can give a better technical answer than I can. Simply put I think of the microphone circuit as being electrically insulated from chassis ground - hence you need too run two separate wires back to your radio. Think of it this way ... The microphone receives a steady signal on one wire - you speak into the mic - that changes the signal which now go back to the radio in the other wire ... :-) The shield you have on the wire is to prevent any changes to the signal in the two wires ... All the best Jan > On Nov 26, 2015, at 01:38, sacha wrote: > > > Jan, > > I think at this point I would agree with you: the problem is most likely related to the voltage regulator, not to switches. > > I have ascertained that the noise is entering through the wires, not the antenna as its volume is independent of the radio volume. > > I also tested the noise suppressor capacitor (cessna part 0770038-2) today with a multi-meter but I could not get it to give a reading so it may be fried. Although I just realized that I did not make sure it was discharged before I attempted to take the reading. I'll have to take that reading again. Nevertheless, the look of the part (an old rusty box), age of the plane (43yrs young) and the fact that I have seen capacitors fail in other equipment makes me think this might be a good candidate for replacement. > > Regarding insulation of mic/headphone jacks, is it correct that mic jacks must be insulated from the airframe, but the headphone jacks may either be grounded to the airframe or insulated with a separate ground wire running back to the intercom? If it is correct, can someone explain the logic? > > Happy Thanksgiving > Sacha > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=450304#450304 > > > > > > > > > > ________________________________ Message 2 _____________________________________ Time: 06:52:11 AM PST US Subject: AeroElectric-List: Re: Rotax ignition wiring From: "user9253" Happy Thanksgiving ! -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=450310#450310 ________________________________ Message 3 _____________________________________ Time: 06:52:22 AM PST US Subject: AeroElectric-List: Re: Troubleshooting radio whine/noise on C essna 182P From: "user9253" The microphone jack should definitely not be grounded locally to the airframe, because other varying current (noise) through the airframe will get amplified along with the microphone signal. It is good practice not to ground the headphone jack either. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=450311#450311 ------------------------------------------------------------------------------------- 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.