Well, I too am an "antique" and cut my detecting teeth with a
Garrett Master Hunter. Charlie Garrett perfected the BFO and
for their time his were definitely the Best of the Breed.
Being proficient with BFO's called for excellent Hearing, since
the change in pitch (upward) was the response to any metal target
and the deeper the target the slighter the pitch. This was of
course also dependent on the target Size. A medium to fast
motorboat setting was the best for best hearing the pitch change
for most users with experience. Plus, the nature of the BFO
gave it perfect pinpointing ability.
The metal setting meant a rise in pitch for metal
and a drop in pitch for mineral (black sand or iron oxide), so
for this reason the BFO earned it's place (and respect) in those
early days before transmitter/receivers. Because of the more
challenging nature of pitch changes, the venerable BFO was
just plain FUN to use, believe it or not. But again, this was
also because of Garrett's design. To admit though, the main
drawback of the BFO was that it was mostly unusable in high
mineral soil. But get this, when set to the Mineral side (pitch up)
in such mineral soil, one could then hear the pitch DROP when passing over Metal! But this took a lot of patience,which most of us had little of in those heady days of "treasure hunting". But in mild soil, a good BFO worked very well, especially for "sizing" a metal target, within it's depth capability (metal side),
which of course was not up to a modern instrument's standing. But again, they were (to me and my friends) simply
a very FUN device to use!
So, in support of the BFO, I'd like to suggest that we all, as a
brotherhood of treasure seekers, show honor to this humble
instrument that helped pave the way to our modern miracle
machines. After all, every endeavor requires learning to
Walk, before we can Run, does it not?
Luck to All..
..Wayne/TX