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Technical
Tips from Mark W. Persons |
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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. |
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The stories go on and on.
Stop in again sometime. I'll leave the soldering iron on for you.
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Questions? Email Mark Persons: teki@mwpersons.com |
