Can we use portable hook-and-loop type Push-To-Talk (PTT) switches with Sigtronics built in or panel mount intercoms?
A. Yes they can be used but they have to be hooked in correctly. For complete instructions download www.sigtronics.com/pdf/air_pdf/pttmod.pdf to learn how. Q. Co-pilot cannot transmit through the intercom to ATC. The radio is activated but the tower hears no voice. The Pilot can transmit fine. What is wrong? Intercom models SPA-400, SPA-600, ST-400, and ST-600. A. The white wire is tied to the white/red wire because of preexisting PTT wiring. To test for this disconnect the white red wire as close to the intercom as possible and then try to transmit on the co-pilots side. If you now can transmit you do have this wiring error. Rewire the pilots PTT switch to only go to the white/red wire and of course to point “A” ground. If necessary you can download your intercom’s installation instructions by going to the Aviation Intercom technical page and selecting your intercom model.