Aureous

You say that being 'packable in a backpack' is a major requirement....this leads to the Axiom once again. This is something that the GPX will struggle with. I think your decision is already made for you....

100% factual. Not an opinion. TRUTH. 👍

When I lived in Scotland, I once went on a train past the Kildonan train station and saw a big patch of diggings near there....looked 'juicy' lol. Went panning at Baille an Or a couple times, the gold was actually pretty good and plentiful. The upper hills benches have been ignored.

I did similar, my modded 4500 was easily more quiet with the shield attached. It was an easy conclusion for me. Didn't shut up the noise entirely, but the difference was obvious.

I simply applied the copper tape (2x layers) to the inside of my 6000 control box cover (DD leather products). Ideally, it needs to be directly connected to the internal ground of the graphite paint shield inside the control box as well....but unless a ML tech does it for you, the warranty is voided. 😞

I wonder who put you onto that??? 🤔 The shield is actually .5mm thick copper tape. You can do this to any detector just by buying the tape for shielding electric guitars. Cheap off Ebay, Aliexpress, Amazon etc. Done it to my 6000 with noticeable effect.

Its very subjective.....which model detector you are modding, what exact size/shape gold you're hearing, soil conditions, coil design and size.... On some test patch evaluations, (pre-drilled horizontal holes, targets inserted via wooden dowel) I've seen improvements from as little as 10%, right up to almost 50%. Once you get past the 20% mark using an earlier GPX and 18"+ mono coil sizes, you're well within 'flog a GPZ' range.

The GP Extreme-> GP3500 were all just modifications to the same board and the GPX4000-> GPX5000 were also all (almost) just modifications to the same board.But since the demise of the 5000, their outlook has certainly changed. I think Steve said that a lightened and modded version of the 5000 , sold C. US$2,000 would be a massive seller....so ML don't have to stretch budgets to create a worthwhile detector.The GPX series has already made its $$ (the 4500 is the record holder for the biggest selling PI in history) and doesn't need to recoup any development costs. Add sub-boards for Voltage front end gain, frequency change selector and some upgraded timings (all just code of course) and updated, superior components and voila! Most of the post-development hard work has already been by Woody, Ismael and Mick.

I had my old 4500 modded about 4 years ago. Prior to that, I'd owned it for 3 years. In those 3 years I found only 5oz with it. Once I had it modded, I got 6oz in the 1st 12 months. The flat-wound mono coil I used certainly added a degree of 'punch' but overall, it was way more sensitive and hit deeper. I went back over lots of old territory that I'd given up on and pulled gold on most locations. The mods have evolved a lot in the past few years and have gotten better.

The first mods were done by Barrie Johnson and Ken Roberts, for the SD2000 only. Ismael Jones expanded on this with higher sensitivity frequency crystals, voltage regulator and filters, plus an amp. He then created mods for the GP's and Woody also started around the same time. Mick Spiteri came on the scene when the F1A4 mine detectors were being dumped on the market and he created the mods for those and then expanded into all the other ML PI's. Ismael still has his site up and not sure if he still does the actual mods.... he has the info on the mods for all the machines up to the GP3500 for anyone to download: Ismael Jones site

Mick at Detectronics does mods for C. AU$2K. Woody is more expensive as he's trying to slow down demand. Wait times are approx 4-6 weeks after supply of your control box.

Its all about the mineralization....lots of ironstone. All other settings there are fairly unusable. Phil's video (on my post) shows the black iron soil well. Its well accepted that the big 19 is totally useless in hot ground here... it has zero benefit over the stock 14. X coils are a different matter....Phil doesn't use them I believe.

There are a few people I am acquainted with, or know from FB, that have sold their 7000's and bought cheap'ish 5000's and got them modded. It seems the current mods with the Very low frequency, plus the front end gain can beat the 7000 by a large margin on bigger, deeper gold when using 18" or larger coils. Sounds odd I know but numerous test patch trials over the past few years have convinced some serious operators to give up on the 7000. I am tossing up on whether to mod up an old SD2200 due to a new set of modifications incl a slow timing change, plus the frequency adjust and gain. The option of selecting Channel 1 ONLY is also baiting me. When all the serious operators are demanding depth and no manufacturer is supplying it (the GPZ was released 8 years ago!), then all options become worth a look. An interesting video of a test is here:

Yes, loud, sharp erratic pings as it discharges. Ya dont wanna touch any statically charged plastic either, electric shock will occur. Maybe a trailing discharge wire will help...

Polycarb is still a plastic and may elicit a static charge from friction with soil and rocks, especially quartz. But it might not in your case, trial and error I suppose. 🤔

Minelab's biggest problem is that they don't have an actual product end-user on the board. Just like politicians, 'they don't live in the real world'. No concept of just how poorly the 'biggest detector manufacturer in the world' is regarded by PR standards. No concept of customer expectations either. Their ignorance and indifference will allow other players to etch away at their market dominance....look at Nokta for an example. There are a couple of other minor players who are developing new designs in the prospecting arena also. It only takes one super successful design and Minelab suddenly have a problem. With their decline in revenue, anyone would think that now is the time to announce and release a replacement for the GPZ..... we now have to wait until 3rd quarter of 2024 I suspect. By then, it might be too late.....

Funny about that, Jim Normandi often said wacky things in his latter years...possibly another case of that mentioned here. I was thinking perhaps he meant "A way to remove gold from your quartz specimens" instead lol 😁

The coax may still be use-able, just heavily wrap the split section with elec tape and do a test. To replace the coax cable entirely is a much bigger job....you have to use enameled coax with a braided outer core and resistance of <.1ohm per metre. Stripping the enamel off both cores will do your head in if you're not familiar with various procedures. Couple that with the complete disassembly of the coil, careful retention of the shielding paper and screen wire, ablation of the solder joint cement....yeah, you get the picture....😱

@Northeast if you ever need more advice on home building it yourself, just PM me. As you may recall, I've built 5 of these. Conveyor belt mat is the best option....as Reg says, the lino will abrade to shreds in no time. I have all the wire, shielding, inductance and resistance specs at hand. SD2200 may just be the best option. A folded mono AI coil will need to be run in mono mode, not DD. The Coiltek 'Zulu' or 'Mothership' coils are wound as a DD though.

Detech were considering making Axiom coils also...no doubt these will be half the cost of the Kazakh coils. Just a matter of who does what, when. Good to see someone has made a start though...

The higher frequency doesn't lend itself to useful discrimination nor depth. Which is why we've never seen it. It would need to be a multi-frequency design and this type of design effort is something we will never see from FTP. Management is too disinterested to bring anything useful to market nor compete with the 'Big 3'.

I would say that the initial batches of both flat-wound mono's from the Malaysian contractor were woeful. Anecdotal evidence from the vast majority of users in 2022 would back this statement up....including me. If this coil has been manufactured since, and has been of better quality, is uncertain. Dealerships here tell me that very few have been sold this year as customers are happier with the quality of the 14x9 Coiltek coil and a great many are waiting for the NF 16x10. Word of mouth bashing of the 17" has also lead to lower sales.... 'Nobody wants them' seems to be the phrase often repeated by the 2 dealers Ive spoken to...

Ive only seen and used 2 of them. Both groaned like a kicked drunk. Had to dumb them down to manual 1 or 2 in difficult to even get past the noise. Small target quality was decreased anyway. Unless the quality has increased (akin to the 'better' 11" monos made since May), I would wait for the NF 15x10. Although the Coiltek 14x9 is pretty good I hear. Both owners of the 17 elliptical mono's I knew got rid of them very quickly.

Of all the coils available for use with the 6000, the 11" ML mono is by far the worst. Poorly made with crap shielding quality, bunched or gapped wiring and quality control was practically non existent. In quiet soils, it will work OK but in hotter soils, it will groan like a hangover. This is a by-product of it being a flat-wound mono, they all 'hear' mineralization to a greater degree....which is why neither aftermarket coil manufacturers use this design. By far, the quietest coil is the NF 12x7 mono. I hope that the square-block wound mono design that NF use, will be replicated in their 16x10 and 8.5x6 monos as well. Quiet means stable and stable means performance improvement. At the moment, the Coiltek 10x5 mono is the most sensitive coil out there...by a mile.

The only actual type-for-type replacement still manufactured (high frequency VLF, manual GB) is the Fisher Gold Bug 2. But, as Jeff rightly says, the best option is the Garrett remanufactured 24K. Best HF VLF detector out there, by far.