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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 W0MH      

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