Years ago I used a Vacuum-tube Fisher two-box (The boxes are separated by a five-ft pole)
Metallascope for prospecting.
For placer I used it to detect pockets or zones of magnetite and other heavy ferromagnetic
black sands that weathered out of the Volcanic county-rock in the Great Basin Provence of
Nevada, parts of California, Utah. Arizona and Idaho; but I mostly used it in searching in
California and Nevada..
A two-box punches deep; 5 to 10 ft. and can be set to follow accumulations of
magnetic black sands (Magnetite and other black-sand) that are associated with gold due to
both having higher specific gravity.
The Vacuum-tubes were replaced by transistors during the 1950s and the Fisher Gemini-series
are much improved. My tube-type Fisher needed expensive short life high-voltage batteries
to drive the five vacuum tubes and a replacement battery lasts only about 8-9 hours hours and
cost about $50/each. A two-box needs two; one in the transmitter box and one in the receiver box.
The Gemini-series only needs rechargeable AAA batteries and the unit is much lighter in
weight and has VCO and other mods...
I know their are Gemini-users out there? Anyone wish to post their success? This could
make a good thread about the prospecting virtues of a Fisher two-box.
Metallascope for prospecting.
For placer I used it to detect pockets or zones of magnetite and other heavy ferromagnetic
black sands that weathered out of the Volcanic county-rock in the Great Basin Provence of
Nevada, parts of California, Utah. Arizona and Idaho; but I mostly used it in searching in
California and Nevada..
A two-box punches deep; 5 to 10 ft. and can be set to follow accumulations of
magnetic black sands (Magnetite and other black-sand) that are associated with gold due to
both having higher specific gravity.
The Vacuum-tubes were replaced by transistors during the 1950s and the Fisher Gemini-series
are much improved. My tube-type Fisher needed expensive short life high-voltage batteries
to drive the five vacuum tubes and a replacement battery lasts only about 8-9 hours hours and
cost about $50/each. A two-box needs two; one in the transmitter box and one in the receiver box.
The Gemini-series only needs rechargeable AAA batteries and the unit is much lighter in
weight and has VCO and other mods...
I know their are Gemini-users out there? Anyone wish to post their success? This could
make a good thread about the prospecting virtues of a Fisher two-box.