Silverdog Surf Pi

[Buckrogers]

Hi,

just joined the forum an am relatively new to meal detecting. Bought a Silverdog Surf Pi over winter as a project to build and have just finished it. Bit of a starter for me into metal detecting and am wondering if anyone else has one of these kits and as managed to get it to pick up gold at depth.

It seems very good at picking up steel objects at great air tests but I can't seem to get it to pickup gold from more than about two or three inches in air

[Silver Dollar]

You have to have a fast coil to see gold as it decays quickly.

Do you know what the shortest delay you can use?

There may be some mods to make the delay shorter if your coil can handle it!

[Qiaozhi]

It seems very good at picking up steel objects at great air tests but I can't seem to get it to pickup gold from more than about two or three inches in air

The problem with the Surf-PI (as regards low conductivity targets such as small gold) is the high gain on the preamp (60dB). Have a look at the Hammerhead II design which splits the preamp over two stages. You should also read Joe Rogowski's "fast coil" article -> Making a Fast Pulse Induction Mono Coil

[Buckrogers]

Thanks for the useful tips. I have the fast pulse induction mono coil paper and re read this evening. Indeed it sounds like adding some shielding to the coil is something I need to look at.

I will have to read up on how to get the shortest delay but the papers I have seen suggest turning the beat frequency pot all the way clockwise to get to the lowest and it seems to pick up gold much better.

Lots of fun anyway for someone to get to grips with the terminology and it has been nice to get back to doing some electronics again