These housemartins were nesting in the roof of the entrance. Most visitors were probably unaware being focused on the chapel ahead.
Simple QRP projects, 10m, 8m, 6m, 4m, FT8, 160m, WSPR, LF/MF, sub-9kHz, nanowaves and other random stuff, some not related to amateur radio.
It would appear that lithium-ion batteries look optimal for range and weight. The disadvantage is that lithium is a rare earth material with...