compadre preset ground problem(?)

[giuhalftrack]

Hi, i manage to buy a tesoro compadre pro, it is the French version, black and with an added potentiometer for the speaker volume.

I know that this machines have a preset ground (inside box trimmer) and I suppose this is set to 0° degress phase or +0.5° phase (info from George Payne writings) anyways we can say that the preset ground is very positive...

I hunt in a river were the hot rocks are common (meta-basalts from alps) so my detector react to them...
at my house I try to move a ferrite piece over the coil and the detector gives a clear signal... is this normal ??? I think not...

maybe the previous owner have set ground accordind to his needs.. let me know.

[Carl-NC]

Preset GB is usually set to ferrite so your ferrite should not react. It's possible some components have drifted slightly and the GB just needs to be re-calibrated.

[giuhalftrack]

Preset GB is usually set to ferrite so your ferrite should not react. It's possible some components have drifted slightly and the GB just needs to be re-calibrated.

thank you for your reply Carl, I use a piece of ferrite from an old cable filter... I will open the detector to look inside...
I don't know if I wanto to make the ground adjustable (like I do in the silver uMax) or leave it like that.

Should I calibrate the ground looking at waveforms on the scope or just balancing a ferrite over the coil ?

[Carl-NC]

Just bob the ferrite on the coil and balance to that.

[giuhalftrack]

Just bob the ferrite on the coil and balance to that.

ok I will do it.
thanks

[giuhalftrack]

now it is working good !! it takes a tiny adjustment... I wonder if it is worth to put a switch High/Low with 2 ground presets like a mojave..

[EL NINO]

If you use concentric coils on Compadre in heavily mineralized terrain, it makes sense to switch low / high.. but when using DD coils, it is necessary..

[giuhalftrack]

If you use concentric coils on Compadre in heavily mineralized terrain, it makes sense to switch low / high.. but when using DD coils, it is necessary..

ah ok.
I prefer concentric coils, but as we know (and as you said) they are affected by gorund more of the DD coils.

I ask you in the name of science to measure for us the "presets" on the switch low/hight so we can modify our compadres