There are several ways to get assistance with any Sigtronics Products:

1. This FAQ document has help on the most common asked questions.
2. All Sigtronics products installation and operating instructions are available for downloading on our site, press here to go there. www.sigtronics.com/air/tec_info_air.html
3. By Telephone: 909-305-9399 for assistance 8:00 a.m. to 4:30 p.m. Pacific time Monday through Friday except holidays.
4. By E-mail: tech@sigtronics.com
5. By FAX: 909-305-9499.
6. Or you can write us at:
   Sigtronics Corporation
   Customer Service
   178 East Arrow Highway
   San Dimas, CA 91773
   U.S.A.

If you do contact Sigtronics for technical assistance, along with the problem you are having, you will need to provide information specific to your application. Information like the Sigtronics product model number, type of aircraft, make and models of the aircraft radio(s) / audio panel, and make and model of other headsets you are using if applicable. If the problem is with a Sigtronics intercom, also include the serial number.

If possible contact Sigtronics first via phone, E-mail, fax, or letter as above to determine where problem may be. Most intercom / headset system problems turn out to be installation or usage related and not caused by a faulty product. If it is determined that a Sigtronics product is in need of repair box it up in a suitable shipping container and send shipping prepaid to:
Customer Service
Sigtronics Corporation
178 East Arrow Highway
San Dimas, CA 91773
U.S.A.

No return authorization number is required. We do however, want you to include a note with your daytime phone number and description of the problem you are having. Include additional information like type of aircraft, make and models of the aircraft radio(s) / audio panel, and make and model of other headsets you are using if applicable.

If the unit is out of warranty and requires payment for repairs we normally send it back UPS COD. If you prefer you can include credit card (VISA or Master Card only) information in your letter. We will need the card number, the expiration date, and the card holders name as it appears on the card. Normal repair turn around time is 1 1/2 weeks in house or less plus shipping time to and from Sigtronics. If necessary, faster turn around times can be arranged by request.

The PDF format allows you - our customers - to get Sigtronics product instructions that look and print out exactly as the originals. This is true regardless of the computer system you are using for example Mac or PC. The PDF format printouts are much cleaner and therefore much more readable than FAXed documents. As long as you have Adobe Reader version 5.0 or greater you can view and print any of these instructions.

Just click on the Adobe Reader button on the Sigtronics technical pages. It will take you to Adobe's site and allow you to download and install the reader for your particular system. If you are in a hurry press here now! www.adobe.com

You do not have Reader Version 5.0 or greater. Sigtronics technical files will not open correctly in Readers versions 3.X and lower. Just download the latest Reader now and install it and you will be able to use the technical pages.

Yes, all Sigtronics Portable intercoms will work. There is one caveat though. When you transmit this way all microphones on the unit will go out to ATC. On two place intercoms this is usually not a problem. On four place and above it can be more problematic. You will have to tell every one to be quiet while you are talking to ATC.

There are three possible causes for this problem. The first is to make sure you are using the headphone output jack on your music source and not the line output jack - if it has one.

The second is to make sure the cable that you are using between the walkman and the SPO is correct. It needs to be stereo on the music source side and combine both channels into one (monaural) on the SPO side. Also make sure it is a straight through cable without any attenuation in it like a "dubbing" cord.

Third and finally if the other two check out fine and you are still having low audio, you could have an older SPO that does not amplify the AUX input audio. We made a change a few years ago so we don't have this sort of problem with the newer lower powered walkmans. We can update your unit to the new circuit, if necessary. There is a small charge for this. Contact Sigtronics for the details.

Yes they can be used but they have to be hooked in correctly. For complete instructions download www.sigtronics.com/_pdf/air_pdf/air_intercom_pdf/pttmod.pdf to learn how.

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.

Yes it is possible by adding an additional switch to the installation. For details download the pilot isolate pdf www.sigtronics/_pdf/air_pdf/air_intercom_pdf/pilotiso.pdf.

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.

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.

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/air_intercom_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.

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/air_intercom_pdf/fltngrnd.pdf for complete instructions details.

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 https://www.sigtronics.com/_pdf/air_pdf/air_intercom_pdf/exmicint.pdf.

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 https://www.sigtronics.com/air/tec_intercom_air.html and select the appropriate instructions and download.

See the linked PDF for instructions.

The answer is a qualified yes. You can buy less expensive headsets but be careful about buying poor performing or poor quality headsets. There are two main reasons for this. The first is your friends and loved one's hearing are just as important as yours. Many low priced headsets do not attenuate the back ground noise very well putting the wearer's hearing at risk.

Second, poorly designed headsets bring down the performance of any intercom system. Actually the noise you hear in your headset through the intercom is that generated by the noisiest microphone on the system! Some low priced headsets can induce so much noise into a system as to make it virtually unusable. That said, which inexpensive headset should you buy? For the cost conscious consider the Sigtronics model S-20 headset. The S-20 is Sigtronics least expensive headset but at the same time does not compromise on performance or quality.

It is possible to use a military headset in general aviation aircraft but it will require a specialized adapter. Military headsets are different than general aviation headsets in several ways. The first and most obvious is the plug. Most military headsets use a single four conductor plug (U-174/U type). General aviation headsets use two plugs.

Another difference is the microphones. Military headsets use a 5 ohm non-amplified microphone. General aviation mics are amplified and powered by the aircraft intercom or radio. The microphone level and impedance are vastly different in the two systems. Therefore to use the military mic in general aviation aircraft you would need to add a mic amplifier between the microphone and the aircraft.

The final difference is the speakers in the ear cups. Military headsets use 8 ohm speakers while general aviation headsets use 600 ohms. This also can be converted with additional electronics.
One approach is to buy general aviation microphones and speakers and change out the military ones. This works but is expensive. You would also need an adapter for the cable plug. The best approach is to buy a headset made for general aviation and save the military headset for the military aircraft.

If you need to use a military headset in general aviation aircraft, Sigtronics manufactures an adapter (p/n 900119) that can take care of all three problems. It converts between the two plug arrangements and the microphone / speaker differences.

Usually, this problem is not a headset problem. It is caused by a design shortcut used in inexpensive intercom systems. General aviation headset microphones draw power from the intercom or radio mic line they are connected to. Some poorly designed intercom systems hook all the headsets to one mic line. When this is done all the headsets must share the same power. Because different headsets have different power requirements one may draw just enough power so it works but there may not be enough left over for any of the others to function. With this type of design two identical headsets will work most of the time but get different types and models then you will have a problem. The only way to fix this is to modify or replace the intercom system with one that uses separate mic input lines. All Sigtronics intercom systems use separate mic input lines and as such do not have this problem.

What happens depends on the design of the intercom system. At the very least you will get reduced performance. At most you or anyone else in the aircraft may hear music but will not hear intercom or aircraft radio reception. This latter situation is the reason that monaural headsets should not be plugged directly into stereo headset jacks wired for stereo. If stereo to mono plug adapters are used then the intercom and headsets will function correctly. Since the headphone plugs used on general aviation headsets are the same as that used in home stereo equipment, these stereo to mono headphone plug adapters can be readily purchased at your local electronics store.

The gory details: Stereo headset jacks have three electrical connections. A regular general aviation monaural headset has a headphone plug with only two electrical connections. When you plug this two connection plug into a three connection stereo jack it shorts two of the connections together (the RING and BARREL). If the RING connection of the jack is used, this shorts out that audio channel to ground so you will not hear it in your headset. You will still hear the music from the other channel in both ears of the monaural headset but you are only hearing half of the audio. Depending on how the intercom system is configured this may also prevent other headsets on the system from hearing that channel. Finally if the particular intercom system directly ties both channels together when aircraft radio or intercom traffic occurs both channels will be disabled since one channel is already shorted to ground.