Occasionally listeners ask why they can hear KARI more clearly during the day than at night. The simple answer is our authorized power at night is limited to 2500 watts by the Federal Communications Commission whereas our daytime power is 5000 watts. These limitations are imposed in order to prevent interference with other stations on the same frequency. FCC regulations protect existing stations from interference by subsequently licensed ones. Our coverage area is also shaped by the configuration of our antennas, the power distributed to them, and the phase relationship between them. 

Between sunset and sunrise AM radio transmissions can travel great distances by bouncing off an atmospheric layer. Without restricting the power of some stations at night these “skip waves” could result in unacceptable interference between stations all over the continent. Here is a list of power change times for KARI 550 month-by-month:

Jan. 8:00AM/4:45PM PST Feb. 7:15AM/5:30PM PST Mar. 6:30AM/6:15PM PST* Mar. 7:30AM/7:15PM PDT Apr. 6:15AM/8:00PM PDT May 5:30AM/8:45PM PDT Jun 5:00AM/9:15PM PDT

Jul 5:15AM/9:15PM PDT Aug 6:00AM/8:30PM PDT Sep 6:45AM/7:30PM PDT Oct 7:30AM/6:30PM PDT Nov 7:15AM/4:30PM PST Nov. 8:15AM/5:30PM PDT* Dec 8:00AM/4:15PM PST

*Daylight Savings Time Begins March 14 at 2:00AM.

*Daylight Savings Time ends November 7 at 2:00AM.