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

 


Technical Tips from Mark W. Persons
Frequency Measuring Still Required


    It is a good idea to check frequency on every transmitter you work on annually.  It only takes c couple of minutes and is easy to do.  The carrier frequency limits for FM broadcast transmitters are +/- 2 KHz.   The 19 KHz stereo pilot needs to be +/- 2 Hz.  For AM radio stations, the carrier frequency limits are +/- 20 Hz. 

The FCC deregulated the requirement to do frequent measurements, but still continued it the obligation of stations to comply with the standards.  

You never know what you might run into.  I remember a client calling to say he could not get the RBDS 53 KHz data channel to work on some FM receivers.  A carrier frequency check revealed the station was 8 KHz off frequency. 

When an AM is off frequency, you will hear a beat note between that station and others on that channel when listening in fringe areas.  If the two stations are 200 Hz apart, you will hear a 200 Hz tone in your receiver.   


The stories go on and on.  Stop in again sometime.  I'll leave the soldering iron on for you. 
Mark W. Persons   Ham WMH

 Questions?  Email Mark Persons:  teki@mwpersons.com         

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page last edited 02/22/2016