messed up my Tesoro coil (concentric)

[kt315]

[Koala]

Back to square one. New coil does not null very well over 400 mv but detection distance is good ??. Distance is the same if the inverting end is tied to ground but there is no measurable voltage on the live end. Might be a bit noisy in the house. 4mv of noise with the detector off. 11mv of noise when switched on all peak to peak on the RX.


Made a new shield used graphite and PVA and painted on some cardboard came out at between 10k to 20k edge to edge.



Do I need to space it away from the windings

[WM6]

Do I need to space it away from the windings

This is always advisable, despite in case of graphite shield not so important.

[Koala]

Second 6" coil seems to be a lot better. Shield out at around 10K per square. However under the surface its between 1-3K. Not connected the shield to anything in the coil and only to TX ground in the control box. Been out to the garden for a test. Buried Victorian penny at 10" was detectable which I was not expecting to get at all. In all metal mode the threshold is nice and steady when lowering the coil to the ground even over wet grass. Seems stable in discrimination mode but time will tell a clumpy uneven field is not the same as a nice lawn.