The FM Modulator is designed for use in Tepco translators. Its purpose is to provide a method of switching the FM translator input from RF (off air) to audio.  This is useful in producing local originated announcements as per FCC rules.  This unit can also be used with an upconverter and chassis to provide an audio to RF conversion for satellite use ("satalator")(see J-317MST or J-340MST).  By defeating the modulator's built-in pre-emphasis, the output of a stereo generator (see FM-6) can be fed through this modulator for stereo operation.

For upgrades, the modulator can be field installed into a translator or the unit can be sent to us for modification.

SPECIFICATIONS
 

• AUDIO FREQ (for distortion and SNR specs): 50 HZ 1KHZ 7.5kHZ l5kHZ
• SIGNAL to NOISE: 65.5 DB 79.5 DB 80.1 DB 77.7 DB
• DISTORTION: 1 % .5 % .2 % .1 %
• DEVIATION: factory set for 75KHz
• AUDIO INPUT:  balanced 600 ohm (can be configured for unbalanced Hi impedance)
• AUDIO INPUT LEVEL: 0 dbm/.78 V RMS for 75 kHz deviation (adjustable)
• PRE-EMPHASIS STANDARD 75 usec (can be defeated for composite stereo signal)
• INPUT CONNECTOR:  "F" type (if used with downconverter)
• IF OUTPUT FREQUENCY: 10.7 MHZ
• IF OUTPUT LEVEL: 0 dBm nominal into 50 Ohms
• OUTPUT CONNECTOR: type "F"

CONTROL REQUIREMENTS

To change translator from RF input to audio input jump terminals 4 & 5 on translator barrier strip.
To switch back to RF input, open the same two terminals.  (This is commonly done with a switch or relay.  The voltage on these terminals comes from the control transistor base.)

For more information, e-mail us at tepco@rapidnet.com .