Making a 15" round coil.

[Jim in Idaho]

I did this with my spectra v3i but im having lots of trouble with ground effect when i raise and lower the detector im getting signal from the ground.

Will it not ground balance, Stefan?
Jim

[stefan-s]

Will it not ground balance, Stefan?
Jim

Indeed, that seems to be the problem ad least in my opinion. Depth etc is really good but the ground effect is the only issue im not able the solve probably because of my lake of knowledge of how to building these kind of coils (im have the same issue when i try to build a DD coil). Maybe i make mistakes with shielding or something i don't know i build several new coils but cant get it working properly.

[Jim in Idaho]

Indeed, that seems to be the problem ad least in my opinion. Depth etc is really good but the ground effect is the only issue im not able the solve probably because of my lake of knowledge of how to building these kind of coils (im have the same issue when i try to build a DD coil). Maybe i make mistakes with shielding or something i don't know i build several new coils but cant get it working properly.

So have you checked to be sure the RX coil is not "seeing" the transmit coil? The RX coil has to be in "null" from the TX coil. You may need to tilt the RX coil slightly, up and down, to be sure it's in null.
Jim

[pito]

ground effect is the only issue im not able the solve = The easiest way is to use quadrature detector, you will have Ux and Uy, you need to rotate both synchronous switching signals until Uy =0 when machine is close to the ground.
Maybe i make mistakes with shielding = good shielding = detector is not responding to human bodies.

bring two hands close to the Rx coil

[Jim in Idaho]

ground effect is the only issue im not able the solve = The easiest way is to use quadrature detector, you will have Ux and Uy, you need to rotate both synchronous switching signals until Uy =0 when machine is close to the ground.
Maybe i make mistakes with shielding = good shielding = detector is not responding to human bodies.

bring two hands close to the Rx coil

For people without an engineering education, that might as well be in Greek.
Jim

[stefan-s]

to not to pollute your topic i made one myself:
https://www.geotech1.com/forums/foru...ox-for-spectra