Hey Carl M. How can this detector work??

[www.ebay.com]

Seems the coil is metal...? is the actual tubing the transmitter??? I would assume BFO??

Says an Apollo model...Wasn't apollo a line whites made for a private firm like their sears units..

Keith

“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla

I assume it's a BFO. Amongst my electronics bits and pieces I have an experimental BFO coil I made, which is entirely enclosed by a heavy braided cable screen ( of tinned copper ) and it didn't seem to affect the detection performance. It's purpose is shielding, to reduce capacitance effects that would take place when the coil was close to the ground.

I agree with Pimento... probably BFO, looks like the coil wires are shoved through the tubing and connected under the plate. All that excess aluminum gets tuned out.

Thanks Pimento And Carl..

First metal encased coil I've seen..!!!

Scouted around on ebay and saw this one also.. I believe it may be metal channel tubing ...
[www.ebay.com]

thanks

Keith

“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla

Yep, I have an old Roth similar to that one.

You can also make a coil out of tubing, where the tubing is the winding. This makes it a single turn coil. I've seen a PI detector with this kind of coil. The White's TM808 also uses a single-turn coils made from aluminum rod.

You could make your own 2-box, Keith ! Here's the Wait / Harrison project, published by ETI magazine.
[www.geotech1.com]

And (assuming you're registed at Geotech1 ) here's a neat example build, showing the thick wire used in the single-turn transmit and receive coils:
[www.geotech1.com]

A detector that can tune out aluminum??? Hmmmmmmmmmmmmmmmmm I have an idea!!!!.............................................