(Sporadic E - ionisation layer reflection, generally May - October in UK; multi-hop distances can be several hundreds of miles & sometimes thousands ... Crystal Palace Band 1 sound has been received in Australia before now;
Tropospheric propagation generally associated with slow-moving / collapsing areas of high atmospheric pressure - temperature layer inversion can further enhance these effects)
Back on topic!
Sounds like you've got the '8640B eating out of your hand now
What make/model analyser do you use there?
Guy