Metal Detecting

Anybody make a short adapter to allow whites coils to be used on rutus alter 71’s?

I have a 3x18” Bigfoot coil rated for 3khz-15khz. Rutus runs 4.4-18.4 kHz. If I stayed between 4.4 and 15 kHz I’m thinking it would work if it was wired correctly and internal parts would work with the rutus. The rutus and whites have different pin connectors so a short cord with different ends would be necessary.

That Bigfoot coil would be amazing if it is compatible.

Anyone know if this has been done or available?

It's an interesting challenge, you're almost certain to be the first to try it. Do you have an electrical multimeter ? I can probably help you work out the pinouts needed.
One potential problem: I recall the Bigfoot has a figure-8 receive coil, meaning the front half of the coil behaves opposite to the rear half. The DFX / V3 ? had some mode that was capable of handling this, so it worked all along the length correctly. You may find the Alter doesn't respond to half the coil, or has unwanted responses, like double-falses on iron.

I am electrically challenged. You are correct the Bigfoot is a figure 8 wound coil. When pinpointing the rear half of the coil goes dead.

That's a shame, it could've been an educational experiment.