Telex 38109-977 manual Outstanding Features of Each System, Limitations of Each System

2Systems can be powered from a central power supply or local powered modules. Using local power modules allows more stations to be on the system.

3If a station is too far away to get enough DC power, batteries can be used as a work- around.

4Headset User Stations have a microphone preamplifier with a maximum gain around 53dB. Many stations have an AGC (Automatic Gain Control) that adjust the gain to the incoming microphone signal level. Some stations also have a limiter to prevent overload to the intercom line.

5Headset User Stations have a hybrid function to convert the two-wire signal to a four- wire signal. The listen part of that signal is sent to the volume control and then to the headphone amplifier.

6Portable Speaker User Stations usually have a push-to-talk microphone that gives good speaker to microphone isolation. Fixed stations have a panel microphone.

7The cabling used in these intercom systems is usually called out as 22 AWG. Use of a smaller diameter wire such as 24 AWG shortens maximum distances and the number of user stations on a cable.

(Outstanding Features of Each System)

1The Audiocom® system is immune to noise and is a lower cost system. It is used in difficult environments, i.e.: churches, concerts, theaters, and athletic contests.

2The Clear-Com®system is robust, relatively low cost, available as a rental. It is often used for rock and roll tours, other concerts, in theaters, and in smaller outside broadcast trucks.

3The RTS™TW system is very robust, reasonable in cost, rental systems are available almost worldwide. Used every place, but especially where many multiple channels are needed such as the Oscar ceremony.

4Most larger TV trucks carry both a four-wire system and an interfaced RTS™TW system.

5Call Lights and “mic kill” features are in all three major brands. The Call Light signal can be used to operate relays, radio keying, and warning lamps.

(Limitations of Each System)

1Audiocom® and Clear-Com®systems require three wires for a single channel.

2The RTS™ TW system may have crosstalk (but this is rarely a complaint).

3All systems that use microphone cable are subject to distance limitations, as well as the number of stations per cable.

4Clear-Com®systems and RTS™ TW system have less immunity to outside interference (practically speaking, rarely a problem).

18 H a n d b o o k o f I n t e r c o m S y s t e m s E n g i n e e r i n g