Ron,
You are hearing 10 meter automatic,
un-attended beacons.
In the US, they operate between 28.200 and 28.300.
In Canada, and some other countries, they can operate much lower. I
have heard them as low as 28.150.
Most of these beacons run 5 or 10 watts, and the maximum they can run
is 100 watts.
A few run 1 watt or less.
They are a great way to tell when the band is open.
They transmit 24/7.
You will hear similar signals on 6 meters between 50.060 and 50.080,
only not as many as on 10 meters.
--
Mike Duke, K5XU