Attached are a couple pictures of the IDX all buttoned back up.

I did the usual Mr. Bill's Mods, which was easy enough.

Added external threshold control

Along with a variable adjustable SAT control. Rather than just a two position toggle switch which would be set at factory 220K ohms and be able to switch to 375k ohms. I put in a 500k RV6 precision pot, which I can now adjust from 0 to 500k. Allows a much slower sweep speed and a much faster sweep speed.

A single turn external Ground balance pot was indicated by Mr. Bill to use.
Depending which IDX you have it will have either a 25K or 100K ohm pot. If using a 100k pot, you will need to use a 10 turn. For the 25K you could use a 1 turn. I had neither here, did have a 50K, put a 56K resistor between the outer solder tabs which gave me a 26K value. There is really no room to place a standard size 10 turn. Managed to fit mine in place by removing surrounding resistors on the circuit board and resoldering them to the bottom of the circuit board. This allowed the pot to fit in place, tight fit. Ground balancing is very precise.

Had some silver stickers left over from my PI builds with red and black indicator lines for the external controls. Used them as I no longer have a laser printer to produce new ones.

Air test performance with the Blue Max 600 coil is close to the Tesoro Toltec II with the 8" donut coil that I once owned. The Toltec was somewhat hotter than the average ones found.

Now just have to wait until next spring to play with the Classic IDX.

Still have a few projects to tinker with for this winter.-----
Simplex charge cable, Simplex headphone extension cable.
Finish up on my latest Pi.
Resolve an issue with a C&G Lynx (possible mod done by Reg Sniff).
Resolve an issue with a C&G Bobcat II, soon to arrive.
And whatever else comes my way.

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I dig it with a Nokta/Makro product-Legend
and Blisstool V5 The Beast