Question for Dave Emery

[Anonymous]

Hi Dave,
I've been reading the excellent info you provided about construction of a co-planar coil. I have a question though. You didn't mention which screen you connected to the coil shielding, the TX or RX? I know that it wouldn't be both, since you mention on another post about introducing a voltage drop in the RX loop by combining the Gnds anywhere except on the PCB, so I would expect the TX only?
Thanks
Kev.

 

[Anonymous]

Hi Kev, Thanks for the kind words. I connected the shield from the receive coil to the copper strip which connects to the nickel spray on the plastic. Leave the coil end of the transmit coils shield open. Make sure that you wind the bucking coil on top of the receive coil using the receive coil as its former. I would love to hear how well you do with your coil when its finished. Carl Moreland has posted the coil article with full size pictures on the Geotech site (see link) All the best, Dave. * * *

 

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[Anonymous]

George, The coaxial coplaner has a somewhat cone shaped pattern beneath the coil. This means that you have to make more overlapping sweeps to be sure that you have hit ALL the deep targets. My observations have been that the depth is about the same as a dual D coil between the edge of the coil until 2/3 of the way to the center. The center 1/3 goes about 30% deeper. Remember that although a coaxial coplaner will not be as noisy in really hot ground as a mono loop, it will not be as noise immune as a dual D. I am looking forward to reading any reports if anyone has made one of these coils yet.

 

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