|Q. 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.
Q. Can we add pilot isolate to a SPA-400 or SPA-600 intercom?
A. Yes it is possible by adding an additional switch to the installation. Download www.sigtronics/pdf/air_pdf/pilotiso.pdf for the details.
Q. Can I use Sigtronics intercom with a portable or hand held aircraft radio?
A. Yes, but it depends on the intercom model, the radio model, and a few other factors as to how this can be done. Please contact Sigtronics technical staff with the details of your installation and we can provide instructions.
Q. Can I install Sigtronics Stereo Intercoms for use with regular monaural aviation headsets?
A. Yes, you can install any Sigtronics stereo intercom system to use regular monaural aviation headsets. It requires a small wiring change to the installation. See the installation instructions for your particular Sigtronics intercom model for details.
Q. I have an older ST-400 / ST-600 with the RES-400 / RES-600 music switcher. How can I use low level music input like a portable CD or tape player?
A. If your portable player has at least 30 milliwatts of total headphone output power (check your players specifications) a modification to the Sigtronics music switcher (models RES-400 or RES-600) will allow it to be used. Download www.sigtronics/pdf/air_pdf/resms1.pdf for the details on this modification. If your portable player has less output power than 30 milliwatts you have two options. Option 1: Upgrade to the Sigtronics RES-401 or RES-601 music switcher. These new switchers just plug in place of your current switcher and allow even very low output players to be used. Option 2: provide an audio amplifier between your player and the Sigtronics system. You will probably have to have a qualified technician do this for you.
Q. I have an older ST-400 / ST-600 with the RES-400 / RES-600 music switcher. How do I hook it up to a stereo music source with four speaker output wires labeled left +, left -, right +, and right - (floating speaker outputs)?
A. The older ST-400 / ST-600 with the RES-400 / RES-600 music switchers have a three wire music input and cannot directly hook to a four wire stereo. To use a four wire output stereo you have two options. Option 1 - Upgrade to the Sigtronics RES-401 or RES-601 music switcher. These new switchers just plug in place of your current switcher and allow a four speaker wire output stereo to be used directly without any adapters. Option 2 - Connect a three to four wire or floating ground adapter between the stereo and the Sigtronics music switcher. These adapters can be purchased from some stereo supply houses. Alternately, an adapter can be built using basic electronic components. Download www.sigtronics/pdf/air_pdf/fltngrnd.pdf for complete instructions details.
Q. The intercom squelch and volume controls work fine until I select or turn on the aircraft radio(s). I still get talk between the headsets but the intercom squelch and volume controls have no effect. What can I do?
A. A small number of aircraft radios when they are turned on will bypass the intercom of some Sigtronics models. This is because of the design of these particular radios in combination with part of the intercom fail safe design. The most common aircraft radios that do this are the King KY-92, and most Terra panel mount radios. The specific Sigtronics intercom models affected are the SPA-400, SPA-600, ST-400, ST-600, SDB-800, SPO-22, SPO-42, and SPO-62. There are two recommended ways of remedying this situation. The first is to send in the Sigtronics intercom for a factory modification known as the "mic interrupt mod". There is a small fee for this modification. The second way to fix this is to install a small relay in the aircraft that effectively does the same thing as our mic interrupt mod. For complete instructions on how to do this download the "SPA-400/600 External Mic Interrupt Modification" at http://www.sigtronics.com/pdf/air_pdf/exmicint.pdf.
Q. Why can't my passengers and I hear my voice when I transmit on the aircraft radio(s)?
A. Most aircraft radios, when transmitting, provide what is called "sidetone". Without sidetone, you will not hear yourself or your co-pilot transmit to ATC. This can be distracting, especially during instruction, because no one on the intercom will hear the out going transmission side of the radio conversation. Some aircraft radios do not provide this function and other radios are designed to drive only one headset. Therefore, if you have such a radio, the sidetone may be extremely weak or non-existent. If this is the case and the sidetone cannot be turned up in the radio(s), a simple modification can be performed within the Sigtronics intercom to simulate sidetone. The Sigtronics intercom models affected are the SPA-400, SPA-600, ST-400, ST-600, SAS-440, SAS-640, ST-440, and ST-640. For a small fee Sigtronics can modify your unit for simulated sidetone for you but you will have to send it to us. If you prefer to do it yourself or have someone do it for you locally, instructions on how to do the modification are in the installation instructions that came with your particular model. If you don't have the instructions you can contact Sigtronics and we will get be glad to get them to you. Alternately, they are all available on our web site. Just go to http://www.sigtronics.com/air/tecavi.html and select the appropriate instructions and download.