I have many years of experience using RDFs and ADFs crewing and later skippering commercial fishing boats. I’ve shot bearings on USCG and FAA beacons, AM BCB stations, other boats on 2-3 MHz AM and weak net buoy beacons operating just near the bottom edge of the 160M ham band. It’s VERY hard to get useable loop antenna directional nulls on weak signals. DAV and BC 611 are not great DF targets. Signal is too weak unless you are very close. Others may hold different opinions but this is my experience.
73
Mark
AF6IM