Surf PI detects carbon braid tube.

[Pete61]

Hi, recently finished a Surf PI with most of the mods( picks up a 9ct gold cuff link at 6 inches) and decided to check the carbon fiber braided tube I had from another project.
Waving the braid over the coil triggered it at about 6 inches away. Its a 1m length of 25mm rolled up.

Strangely it doesnt detect 5mm dia solid carbon fiber kite rods and a 500gram plastic bag of graphite powder is only seen on one half of the coil. (rhs when in general use position.)

Does this indicate its probably a bad idea to swop out my current 20mm dia pvc conduit lower rod for a CF one?

For what its worth, Im using a plain jane coil, 20 turns of 0.4mm enameled copper wire, 235mm dia, cable tied to a plastic plate( no shielding) and connected to the electronics with RG58 coax.(BNC 50 ohm connectors to make swopping coils easier.)

[Carl-NC]

There is a long thread on the DetectorProspector forums about carbon fiber lower rods:

https://www.detectorprospector.com/t...ber-lower-rods

It is mostly a problem for higher frequency detectors and mostly when the rod is folded against the coil, as when digging a target. A CF rod has a response very close to that of salt water and as long as there is no relative motion between the coil and the rod it is unlikely to cause much of a problem. Add to that the SMPI is not aggressive on low conductors, so I think a CF rod on the SMPI will be fine.

[Pete61]

There is a long thread on the DetectorProspector forums about carbon fiber lower rods:

https://www.detectorprospector.com/t...ber-lower-rods

It is mostly a problem for higher frequency detectors and mostly when the rod is folded against the coil, as when digging a target. A CF rod has a response very close to that of salt water and as long as there is no relative motion between the coil and the rod it is unlikely to cause much of a problem. Add to that the SMPI is not aggressive on low conductors, so I think a CF rod on the SMPI will be fine.

Thanks for that, I'll go give it a read.
Yeah, when kept still it goes quiet, just thought it might reduce depth, but its my first, so still lots to learn.