Janitor Boy Jr wrote:
snip

strange. at 4800, I hear the single "weep" then what sounds like an echo.
4806 through 4810 I hear both "weep, weep" solid. I'll record a few
samples.


A little web research of archives finds mentions of "sweepers" on 4800 +/-
25 kHz of high signal strength in the past five years being an annoyance
across the U.S. and even in New Zealand; consensus amongst respondents
is that they are hf radars for ocean current studies, probably higher
power implementations as opposed to the low power Codar brand systems
documented by the manufacturer at its website. An argument against
OTH radar was that the signals didn't change diurnally or based on
propagation conditions.

Folks with directional antennas could help triangulate these signals; a
little RDF in locations with very strong signals may also be useful.

Michael