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Old November 5th 05, 06:11 AM
Richard Harrison
 
Posts: n/a
Default AM Commercial radio reception

Dave P. wrote:
"Why is it that I can receive WCBS @ 880 kc fairly well at night but
WABC @ 770 kc suffers from phase distortion like you wouldn`t believe?"

I havn`t looked up the directional patterns of the two stations and
don`t know your location. If you should happen to be at the edge of a
null in the nighttime directional pattern of WABC, that would likely
cause distorted fading. WABC may be clear-channel non-directional day
and night for all I know. Not many of these remain in the U.S.A. now.

At 175 miles from both transmitters, you suffer interference between the
ground wave and sky wave from either transmitter at night, at least
occasionally. You probably have solid daytime reception from both
stations, but at night, the signal may be stronger, though variable. The
sky wave is susceptable to variations in the reflecting layers of the
ionosphere at night. These are a function of frequency, reflecting
carrier and sidebands differently at times. This can produce
overmodulation at times in the received signal. Another factor is likely
other stations on the same or adjacent channels which may fade in and
out and cause variation from your automatic volume control action even
when the interfering stations can not be readily identified. An Adcock,
loop, or other directional antenna may produce a big improvement in
reception of the desired signal.

Finally, WABC is owned by the Walt Disney company. Maybe you should
expect Mickey Mouse performance.

Best regards, Richard Harrison, KB5WZI