* 22 Jan 2006: 0650-0710 UTC: 405 khz (unknown): -- --- --. (morse code for "mog"). Four seconds of silence after the call, then it repeats. Signal strength varies from faint to strong over time. Local interference is strong.
According to DXing.com's Longwave DXing page, "[t]his range is used mainly by navigation beacons, which continuously repeat their call signs in Morse code. ...the call signs usually give an idea of the location of the beacon."
A Google search for "navigation beacon" mog found a page of Low-frequency navigation stations. MOG is a non-directional airport beacon in Montague, California. The airport is just south of the California-Oregon border, approximately 300 miles from my listening location.