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Radio Broadcast Technical Consulting and Sales
10032 Island Drive, Brainerd, MN  56401

Modulation Monitor Switch
For AM or FM

Built by M. W. Persons and Associates, Inc.
Made in Minnesota

This is a rack-mounted MM-2A and B Modulation Monitor Switches, can be used in AM or FM broadcast.  The unit manually or automatically selects between modulation monitor samples from main and auxiliary transmitters.
A green light indicates the main transmitter sample is being sent to the modulation monitor.  The bottom yellow light will come on when the backup transmitter is connected to the modulation monitor.  When the 3-position toggle switch is up, a continuous contact closure or +2 volt to +15 volt logic from station switch gear will select the backup transmitter for monitoring.  An open contact or no logic voltage will leave the switch in the main transmitter mode.

When the switch is in the middle or down position, a red light on the right will flash indicating the unit is not in the normal mode.  This is an important reminder to maintenance people who might manually select the backup transmitter for testing.  The light will warn the operator to switch back to normal before leaving the transmitter site.

The rear panel shows BNC jacks for input and output samples.  A 24 VDC power supply is used to run the relays and lights.  The unit is 19" wide x 1-3/4" high.  Variations of the design can be made.  email your request.  Complete schematic documentation is provided.

The MM-2A Switch uses contact closure logic to automatically change from main to backup transmitters.  It is $385 plus shipping. 
The MM-2B Switches uses +2VDC signaling to switch to the backup transmitter.  It is $399 plus shipping.  This version is suited to accept a status input from the AM RF Switch.  Normal lead time is typically one week or less.

March 3, 2017, email: Mark, the MM-2B Modulation Monitor Switch you built for Alexandria worked just perfectly.  Now when Brett changes transmitters remotely, his silence sensor doesn't activate because the mod monitor now has a feed.  Thank you again for putting that unit together for us, and for modifying it to work with a +2 volt sample input.  Doug Thompson, Osceola, Wisconsin.

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Questions?  Email Mark Persons:  teki@mwpersons.com       

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page last edited 05/02/2017