AboutMarc Ebelini Expertise Basis aircraft and engine maintenance. Avionics and other electronic questions related to computers and radio communications.
Experience FAA licensed comercial pilot, A&P mechanic, former authorized inspector, ground instructor certified in aircraft, powerplant and radio navigation. FCC commercial license.
Expert: Marc Ebelini Date: 7/29/2008 Subject: aircraft switches
Question How do i interface an intercom to two kx 170b radios with speaker switch in system, existing wiring terrible, intercom wired and ready to go. com wiring unmarked mess. including relay wired to speaker switch and com select switch. unintelligible mess to me. only option trial and error with voltometer as guide
Answer This becomes a tricky question because I have no idea of how it was originally wired. To begin with the intercom is usually a separate system. The headphone and mike jacks are usually on the intercom panel. So that there is two separate system on board. Integrating the two becomes a more complex but not impossible. The first order of business is to establish how you want it to work. First question would be, do you have an audio control system? These too can be simple or more sophisticated. For instance do you have automatic speaker or phone function. I design this into my custom audio control panels. Later many of the companies sold control centers with this function. Also all our installation used color code wires with a legend to determine the function of each wire. Naturally red was power and black ground. Used green for speaker and blue for headphones and so on.
Would like to be of more help but I need more information about your setup. Also what make and model of you intercom some maybe I can see how it works. But your master plan is important. For example is the aircraft a retractable type, does it have stall warning? Many aircraft have had wheels up landing because the gear warning horn was not wired to the the intercom not allowing the pilot to hear it with his super duper sound proof headset. Will await your response. Look forward to the challenge. Be patient and get it right.
By the way the relay in the speaker line is for speaker muting to prevent feedback.
Will suggest using a Analog VOM for more reliable continuity testing and pay attention to the polarity. Some circuits are polarity sensitive. Also most VOM have positive on the black lead not the red that might be assumed.
