Jim in Idaho

So, they're just making their own version of the Folded Mono. Interesting. I don't think the Folded idea was ever patented. I'll have to check on that. Or maybe it was and Miner John licensed Whites to make their own, or have another coil maker build them for Whites. Thanks for the info. Jim

Good Luck, Chuck...LOL I'm not holding my breath. Jim

I searched Google Patents, and the last patent issued to Whites, that I could find, was dated July of '18, and had to do with a new automatic induction balance system for coils on IB detectors. I don't think it would pertain to PI's. I'm still betting it's a DF. If it's better than the MJ, it's going to be good. Jim

If I didn't have a PI, I'd be all over that package. Sure wish I knew for sure what they did on the new coil. Jim

I'm thinking they ran out of the Miner Johns, since he got burned out in the big Paradise fire. The Folded Mono, that Razorback came out with, and sold by Miner John, was a Reg Sniff design to get around Whites DF patent. So, Whites probably just made a DF that had the same dimensions as the MJ 8 x 12 FM. The patent on the DF design is dated Aug. 9, 2011. US 7,994,789 B1. If that's the case, and the new DF is as good as, or better, than the MJ, it would be really good. But I'd bet my modded TDI SL, with the MJ 8 x 12 is better...LOL The Special Edition (tan box) doesn't have the Sweep Speed mod. Don't know if the new one has the increased battery voltage, either. Jim

I'm wondering if the new coil is simply an eliptical DF. Whites holds the patent on the DF. Jim

Assuming the circuitry is the same as the TDI SL, it draws about 500ma. Jim

Video on 7.5DF and Sadie comparison here:

Yes...I wouldn't feel handicapped with either one of those small coils. They're really close. I thought the Sadie was bit better at the lower voltage, and the DF at the higher voltage. My understanding of Reg's relationship with Whites is about the same as yours, but Whites did finally initiate the second mod, on the TDI SL, in, I think, 2016. I know it was done on the Special Edition, for sure. They never did the sweep speed mod, however. I don't think they ever did any of Reg's mods on the original TDI's. Jim

Finally got to work on testing the 7 1/2DF, 8x6 Sadie, MJ 8x12, and 12"DF. Did a comparison on the 7 1/2DF and Sadie with both battery packs, and a comparison of the MJ 8x12 FM, and the Whites 12"DF at 16v. EDIT: I notice I cut off the early portion of the Miner John comparison. Hope you get enough of the sensitivity of that coil. It works very well on my SL. Jim

It's a stripped-down version of the GMT...more simplified. There's a guy in southern Idaho has been trying to sell an almost new one for several months. He's asking $250. Jim

NO

Really nice work, Shelton! Jim

Yeah....I'm sort of "casually" looking for a Pro model, though I'm very happy with my modded SL. Hope you have some great luck on your trip! I'm heading for the high country next week myself. It's just starting to cool off in my area. Have lots of detecting to do the next few months, before winter sets in. Jim

A guy in central Nevada has been trying to sell an SL model for a month or more. He wants $500 for it. JIm

I'd say 9.84" on a 1/2 gram gold coin is really good! How in heck did you get 14.7v out of 8 1 1/2v AA's? I'm thinking that 14.7v must drop pretty fast when being used? I think you're going to find that MJ 8x12 a really good coil on your trip. Looking forward to a report. I didn't realize the control box on the SE was smaller than the typical SL....interesting. Oh...I get it...that's the PRO next to it, not the SL....DOOOOHHHH! (head slap) Jim

That 8 x 12 MJ coil that comes with the SE is a very good coil from the tests I've done. Jim

Nice work, Karelian! You're going to love that added voltage. Jim

Yes, the nominal voltage is 14.8. That's where you get the flattest discharge curve. The voltage drops to that fairly quickly, and then you get 3 hours or so at that voltage. Anywhere under 4 hours you should be good. Jim

I would appreciate being included. I could use that! Jim

Yes, Chuck, I do. But I have to tell you, when it comes to air tests at least, the smaller coils don't benefit much from the added voltage. The extra boost really helps on the larger coils, however. I need to do an in-ground retest on the 7 1/2 & Sadie with both battery packs. That will be interesting. Jim

In air tests, the Sadie is better. But in my in-the-ground tests on a 1 gram piece of nickel at 6", and a 1.84 gram piece at 10", they're really close, if that helps. Jim

I would guess that that portion of the circuitry is regulated, and the increased voltage has no effect. Jim

I have that coil, and use it. I also have the 8 x 6 NF Sadie. I think the Sadie is just slightly more sensitive, though they're very close. YMMV. I prefer to use the 7 1/2DF, however. Just like swinging it. Recently I acquired an MJ 8 x 12, which is very hard to find since MJ got burned out in the Paradise fire last summer. This is a great coil on the SL model, and maybe the others. For tight spaces, and working around brush, I recommend either the small DF, or the Sadie, whichever you can find the cheapest. I'd like to find one of the 7 1/2 Aussie mono versions to test, too. You'll have to install some spacers on the Sadie to use it with the S:L lower rod. Jim

No regulator required. I would use a charger that allows you to set the max charge voltage, and limit it to 16v, rather than the 16.8v of the typical 4-cell pack That has two benefits...it reduces the chance of a detector problem, and also will nearly double the life of the pack. (number of charge/discharge cycles). You can use a buck converter as a charger...most have adjustable charge current and voltage. Jim