It is most pronounced on 20m, but I recall noticing it on 40m as well.
"It was observed that there were two distinctly different types of TEP that could occur:
The first type occurred <snip> Signals propagated by this mode were limited to the low VHF band (<60 MHz)"
"The second type of TEP occurred from around 1900 to 2300 hours local time. Contacts were made at
144 MHz, and even very rarely on 432 MHz."
The same possibility occurred to me, but I wondered if TEP could even work on such low frequencies. Reading up, my thought was correct, no, the phenomenon is observed on 10m at the lowest. My experience chasing WPX South American stations... 10m, they seem to be everywhere compared to the other HF bands... would confirm that. (Some summers, seems all there IS on 10m is South America!) And the paper KH6AQ cited even says TEP is pretty much a 10m/6m & up thing... That said, it may still have something to do with the equator, but not what is traditionally thought of as TEP with the normal telltale sign of TEP being that the two stations are close to equidistant from the equator on either side.
All that said... I am no expert, I can easily be wrong, just commenting on what I have read and observed.
