Jim in Idaho

Ya know, Carl, I haven't seen much increase in noise on mine, after doing the mod. I did see a big difference in allowable swing speed, and yet still see very small targets. I think it was a good mod to do, for me. From the sensitivity I've seen on mine, compared to a lot of the videos I've watched, I think my SL is very good. Besides reg's mods, I've also added vernier controls on both GB, and Threshold...makes tuning really easy, and accurate. Jim

I've read (maybe Reg told me) that the flyback resistor (R9) will run hot with increased voltage. That's the first place I'd look if my SL puked. So far, running hot batteries, I haven't had an issue over several years of use. Jim

Here's all I have on the smoothing mods. This was a post, a few years back, from Reg Sniff. " I don't do the mods myself. My hands don't work that well any more so I have a friend do them. He does the work and keeps all the money since the mod is somewhat labor intensive and does require a pcb trace mod. A full TDI mod costs about $125 (return shipping included with $500 insurance) and that includes replacing the preamp with a much better IC, the addition of a small pc board to reduce the noise, a filter change so the regular TDI is upgraded to the filtering of the Pro for a faster response. The mod also includes calibration of certain stages to 1 millivolt to assure the mod works as designed. This TDI pro filter mod makes the regular TDI like the Pro but without the extra GB pot and volume control. The volume control was added to help reduce the noise problem, but with the noise reduction mod, is not needed for that purpose any more. One additional mod is to short out a capacitor which eliminates a third filter that is not needed and can cause weak signal problems. This mod does increase the gain which in turn increases the noise level. Fortunately, reducing the gain using the gain control about 20% or so makes it back to normal. You do gain a little depth but more noise with this mod. One advantage of this mod is weak signals become more reliable.

There hasn't been near as much posted on the threshold-smoothing mods for the Pulse Scan. I own an SL model, so didn't get involved on the mods for the TDI. I'll look around, but I'm not sure I have a copy of the TDI mods....only the SL. Jim

Those mods apply to the TDI SL, not the TDI Pulse Scan. The mod for the original TDI's was to smooth the threshold. Jim

LOL...not a chance Chiil...sorry if I gave that impression. Jim

Answer #1...yes # 2 I have no idea #3 yes An unasked question...can the SPP's be modded for more sensitivity and sweep speed....yes! And, I'm no guru...far from it, though I'm probably dangerous, in that, a little knowledge is a dangerous thing....LOL Jim

I should also mention that Reg had a 3rd mod that I have not done on mine, so can't comment on. I found out only after modding mine, and haven't gotten around to it, yet. I can't remember the details, but the info is out there somewhere. Jim

Yes...the pulse scan TDI, and then the Pro. The pro had better Ground balancing for the Australian market, but sold also in the US. Then the SL version, which fit ina smaller box because they went to surface-mount components, but it also had a different ground-balancing system, which improved the performance. Not much later Reg Sniff (RIP) started testing mods to the SL that improved the performance. His mods, which included improved sensitivity, and faster allowed sweep speed, without sacrificing sensitivity really turned the SL into a great machine. The factory finally relented and adopted the improved sensitivity mod into the factory models, starting sometime in 2015. Then the tan version, which also had the improved sensitivity mod. No factory unit ever had the faster sweep speed mod, though that's the easier of the two mods to do. Jim

I'd buy one of those in a heartbeat, if it available near me, Jeff. You beat me to Jim's only because I was out of Internet touch for a few days in Wyoming. I knew when I saw the post, I'd be too late....LOL Should have known it would be you...Ha!

Forgot to mention...I was using the MJ 8 x 12 coil.

If anybody's interested, mine's a 2013 model. Jim

Just a quick report on my heavily modded TDI SL. It stilll works very well, with my 16v battery packs. My wife used it on a recent trip to South Pass, Wyoming, and found lots of old lead bullets, cartridges, etc. A couple of days later, I took it out nugget hunting, and while I found no gold, it did find a piece of what looked like chewing gum foil about 3/8" long and 1/16" in diameter. The foil was 3" down. Doubt it weighed 1/2 grain. My TDI isn't a Minelab or Garrett, but it's still very sensitive, and i can swing it all day. The sensitivity and sweep speed mods, along with my vernier controls really make a difference. Jim

I wondered if anybody from this organization is on the forum? I'm a new member, and planning on attending the Aug. 13th meeting at Atlantic City. Jim

Discussion of detectors aside...lol, I'm curious about the amount of gold in the assay. If my math is correct, that's saying 655 +/- ozs/ton. That seems incredibly high to me. No offense to the OP. Jim

Ants, especially harvester ants, have a genetic predisposition to carry back the heaviest items they can find. It's thought by scientists it has to do with maximizing the return for the energy expended while foraging. it may also, in places where it gets cold in the winter, that the heavier items placed on the mound do a better job of protecting it from the elements. The mound is a critical component of the ant's nest. Jim

Great work, Bentley!!!! I really appreciate your efforts, and the link. Jim

I'd really like to have these, myself....thnx! Jim

I have no idea why some SL's tolerate the higher voltage, but some do not. Mine seems to tolerate it well, but I started limiting my max voltage to 16.0. My Sadie also works fine at the higher voltage, but I don't find it superior to my Whites 7.5DF. According to Carl Moreland, the SL should tolerate voltages as high as 18.0, but may require a couple of component changes to do that. I know of only one SL that wouldn't work at 16v, and that one was in the UK....maybe the soil there was the problem at higher voltage...don 't know. Jim

I was just metal detecting close to the impact center of the Beaverhead Crater a couple of weeks ago. It's about 8 miles west of where hiway 93 crosses Willow Creek Summit north of Mackay, Idaho. No visible evidence at all, unless you're an expert. Wandered that country for years, back in my fur-hunting days, and nobody back then had any idea that was an impact crater. It's interesting that Idaho's highest peak (Mount Borah) is right on the crater rim. Jim

Be advised that some aftermarket coils will do this, and also some SL's don't readily take to increased battery pack voltage. Juast sayin'. Jim

You're right, as usual, Steve. The frequency thing actually started with flight, and radios. The engineers knew that the laminations in transformers were extremely heavy, and figured out they could get the same performance with much smaller transformers by simply raising the frequency they operated at. The new digital welders take advantage of the same principle, as do the inverter generators.....same results in smaller, lighter packages. Before solid state, the aircraft radios operated at 400hz, rather than the 60 hz of ground-based radios. Jim

I'm thinking, Gil, that a switch for the hi-gain might be a nice feature. Jim

Both D20 and 21 are three-lead diodes. The jumper only goes across 2 of the 3 connections on diode D21. It goes across the bottom 2 connections in the pic, as shown. Also, everybody interested in this mod should understand these are very tiny components. They require a magnifying light, and good soldering skills, with a decent quality soldering station. At least IMHO...LOL I was a radar tech in the Air Force, and doing this mod taxed my skills. I've done 2 of Reg's mods to my 2013 unit, and I recommend them. At some point in then future I'm going to do the jumper across Test Points 2 and 31, too. I wasn't aware of that until Gilbert's post, so a shoutout to him, and a thumbs-up Jim

Bear in mind that on SL's made since 2015 have D20, and D21 removed, and the jumper across the correct 2 legs of D21. This was a factory mod. if you want to perfor4m this mod on your pre-2015 model here's a pic showing which legs the jumper goes across on D21. It also shows D20, and C56, which can be removed. Jim