Eric Foster Coil Design

[Goggy]

Hi Altra,

With regards to the Aquapulse and Aquasport, looks like GeoMax is fully up to speed aging them. I'm afraid detectors from the 80's are a little early for my experience with the PI MD's.
I know the Aquasport is essentially the same as a Minipulse. The cylinder Aquapulse however, was a single board when I was servicing and testing them. Still very simple like the Minipulse though.

They used the Ikelite connectors for the Bone-Phone and search coil. All size coils (8", 10" & 15") were 300uH as was the inductance of the 12" and 36" Ferrite Probes.

One common issue we had, was the longevity of (or lack-of) the Hex shaft seals on the control pots.

[Altra]

I also worked on the later Aquapulse 1a and 1b's and like you said they were a single circuit board. The main problems we had with the Aquapulse's were the cable connections to the Ikelite connectors. Once a little water entered, it would wick up the shielding in the orange coax cable and cause false signals and noise. Thank you

[cristiano.sar]

Goggy About the coil shielding, I have seen in some Eric Foster (Ferric Toes) posted photos, that he also used a stripe like the 3M scotch 24, was this used also in production ready coils?
And regarding Vacuum Forming, do you have some photo or detauls of the machines used? (just for curiosity because I also make my own vacuum forming machine and I'm always trying to improve it and get other ideas)

Thanks.

[Goggy]

Hi Cristiano,

The '3M scotch 24' tape was not used in PTL search coils, but Eric may well of experimented and even used this in his own PI designs. The 'Ribbon' cable wrap method and Aquadag coating was definitely used in the Goldscan, Beachscan, etc. designs and maybe a few specials.

With regards to the vacform machine we used: this was the Formech 450 like shown in the picture. It could handle sheets up to 450mm square. We used pin-point vacform molds made by PTL for the simple coils and outsourced molds for the larger vacforms. Hope this helps