Larry Dighera wrote:

Could this be the first ADF receiver?

No. That receiver could be used to drive a radio compass, which was a (by today's
standard) a primitive homing device. It used a fixed loop antenna. The Radio
Direction Finder was derived from this device later and used a loop which could be
rotated. The ADF was derived from the RDF.

So this could be regarded as the grandfather of the ADF.

George Patterson
None of us is as dumb as all of us.