In-line Probe - Coaxial Coil on Ferrite Core

[wallyblackburn]

Got a Fisher F75 and love the machine, but I just gotta have a Sunray-style in-line probe/pinpointer. Sunray ays they might make one later if there is interest.

Anyway, I was looking at the Coil Basics article by Moreland on Geotech (great article) and thinking of trying to make one (yes, I am that desperate). I am leaning towards one of the coaxial coils in Figs 7 and 8. It would seem that if you wound them on a ferrite core to get size down, you would end up with basically a very small diameter coil. I'm actually wondering if that's what the Sunrays are?

Chemelec has some similar examples, but they are single coils for his PI machine.

So...any thoughts, comments, criticisms, help? I have a scope, but I'll have to pick up an LCR meter. I have a bit of electronics experience, but this is new ground for me - I'll take any advice I can get and give credit where it is due.

Thanks,
Wally

[Carl-NC]

I suspect the Sunray probes are wound on a ferrite core, using a coaxial stack as shown in the article. I've been wanting to make one for some time, but time is the problem.

- Carl

[Rudy]

I suspect the Sunray probes are wound on a ferrite core, using a coaxial stack as shown in the article. I've been wanting to make one for some time, but time is the problem.

- Carl

I think you are right Carl. Jeff Kinzli here in California used to make some for White's detectors. He wound them on ferrite cores.