---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 11/24/11: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:10 AM - Re: Re: PTT Y adapter for RST intercom (Robert L. Nuckolls, III) 2. 11:15 AM - Re: PTT Y adapter for RST intercom (messydeer) ________________________________ Message 1 _____________________________________ Time: 08:10:43 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: PTT Y adapter for RST intercom At 11:35 PM 11/23/2011, you wrote: > >Hmm...I didn't think if they were or weren't single or double >throws. Here's Dynon's quote: > >"I took a look at your schematic and I don't think this >configuration will work with the DX15..." > >He's referring to the earlier 'RST intercom mic out ptt wiring.jpg' diagram. Unless he sits down to study the RST intercom internal wiring, he's shooting in the dark. Do you want both pilot and copilot headsets to access the DX15 transmit function? Bob . . . ________________________________ Message 2 _____________________________________ Time: 11:15:09 AM PST US Subject: AeroElectric-List: Re: PTT Y adapter for RST intercom From: "messydeer" Dynon said "the DX15 only sends power to the mic when it is transmitting". I assume this means it's somehow disabled when receiving. Or is there a concern that the radio can't get power to the headsets? I thought they got power from the intercom. Weir said "some radios ground (disable) the microphone audio in receive mode, this type of PTT switch is unsuitable for use with an intercom system." I assumed then that the DX15 would have the mic grounded when receiving as the mechanism to cutoff power to it. I've never read how exactly the RST or any other intercom treats the mic out signal. I thought the VOX switch in the intercom transmitted the mic signal from the pilot's and copilot's mics to both the headsets whenever a certain threshold was reached. From what Weir has written, it sounds like there is no switch or gatekeeper between the intercom and mic out to the radio. Whenever one of the mics overcomes the VOX threshold, the signal goes through the mic out line to the radio. I also thought the intercom would function fine without being connected to the radio at all. There's power supplied to the intercom and the headphones and mics from the headsets are plugged into it. But Dynon said their radio might not have enough power to supply two headsets in parallel, sounding like the intercom does not supply enough power to the headsets. I don't know what needs to happen for a radio to transmit the mic signal. I thought engaging the PTT, shorted the tip to the shell, which caused the radio to transmit. Both the PTT button on the side of the handheld and the one in the stick acted the same way. I thought that once this was done, the radio would transmit whatever signal was coming in from the mic. If the intercom's VOX threshold has been exceeded while the PTT is pushed, the mic signal is sent to the radio and gets transmitted. I don't understand what Dynon means when he says the DX15 sends power to the mic. I know he says it does it only when transmitting, but I don't know what it means. It sounds like power from the radio to the radio's mic jack is needed as well as the signal from the mic out line from the intercom to the radios's mic jack. I'm sure the workings of a radio mic, its power, grounding and transmitting functions are fairly simple to understand, but I don't have that knowledge. I'd be terribly grateful if you could explain this to me, or where I could get this information. The thing that bothers me about wiring the PTT with a SPST switch, leaving the mic out line connected to the radio, is that both the designer of the intercom and that of the radio say this is not a good idea and suggested the DPDT solution. How could I test my radio, headsets, and intercom with my current SPST PTT switches? Would I just hook everything up, set the radio to some locally unused frequency and try it out? > Do you want both pilot and copilot headsets to access > the DX15 transmit function? > While I'm taking flight lessons, I can imagine it would be nice to have that capability for both me and the CFI. Afterwards, it seems unlikely I'd ever need it, except when there'd be another occasion for someone to be taught communication skills. -------- Dan Read this topic online here: http://forums.matronics.com/viewtopic.php?p=359121#359121 ------------------------------------------------------------------------------------- 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.