Hi, Jeff (K8ND),
You wrote:
"To what degree are AM broadcast stations required to suppress their
third harmonics? The station in question is at 610 KHz, placing it's
third harmonic at 1.830 MHz. It's loud enough to obscure weak stations
for a KHz or more."
=====
I think it's 50 dB. We have the same problem here with station KAVL on
610 kHz. It's been there (on 1830 kHz) ever since I came on the band
here in 1976. I and other local hams have talked to the station engineer
from time to time over the years, but it hasn't helped. None of us have
talked to the FCC about it, because it appears to be at least 50 dB down
from the fundamental.
They run 5000 watts during the day, and 1000 watts at night. At night,
-50 dB would be 0.01 watt, but that 10 milliwatts is still S9 when the
transmitter is only about 5 miles away.
About a year ago, a Mexican station on 910 kHz started putting out a big
2nd harmonic on 1820 kHz. It's still there, skips in stronger than the
local one on 1830 kHz.
73, de Earl, K6SE
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