Steve Herschbach

Like I said I replaced the pdf files you posted above with links to the publications directly at USGS and State of Oregon.

As much gold as johndoe gets working black sands for fine gold maybe we should all get shovels! Beach detecting is challenging, and a main difference is that between Florida style white sand beaches and Oregon style black sand laden beaches. Black sand does not refer to color actually. It refers to magnetic minerals like magnetite that are black in color. If a beach is black in color and nothing happens when you drop a magnet it - this is not black sand. On a true black sand beach if you drop a magnet on the beach, a huge load of sand comes up with it. Magnetic sand, laden with magnetite. Here is a picture showing magnetite layers on a beach. The sand is mostly quartz and feldspars, non-magnetic minerals. Magnetite as an iron ore is considerably heavier, and so wave action concentrates it into layers. See johndoes thread above for more examples of layering. Black sand (magnetite) layers exposed on beach Closeup of magnetite black sand. Note dark gun metal granular nature of the sand. Highly magnetic. I currently face a similar dilemma. I beach detect and I prefer a VLF for the discrimination. However, on the west coast you can lose half your depth or even more due to black sand concentrations. Single frequency detectors cannot ground balance to both saltwater and black sand at the same time. You can balance to the sand, or the water, but not both. Multifrequency fixes this problem, but severe black sands still affect multifrequency machine adversely. In fact severe magnetite will even cause a hit in pulse induction performance.... just not as bad as the other options. Pulse induction detectors lose less depth in extreme mineralization. There are many dry land prospecting machines that might do the trick, like the Minelab PI detectors. However, for salt water beach use I personally insist on waterproof detectors and so I leave those dry land units for others to consider. The waterproof pulse induction field is very limited at this time. It divides into two classes. Pulse induction metal detectors that ground balance, and those that do not. A pulse induction (PI) detector by its nature tends to ignore mineralization, so much so that in milder conditions a PI works fine without a ground balance circuit. As I noted above however a PI is not immune to mineralization. A non-ground balancing PI detector will sound off when raised and lowered over true black sands. The more concentrated the magnetite, the more intense these signals will be. The bottom line is that on real bad black sand beaches even a basic pulse induction will sound off if the coil height is varied too rapidly over the beach. In the water with troughs and depressions false signals are all but impossible to avoid. The most extreme situations require a ground balancing pulse induction (GBPI) metal detector. To sum up: Pure white non-magnetic coral beaches - most any detector will work well Even a hint of mineralization - a multifrequency detector has an edge over single frequency VLF where there is both saltwater and magnetic minerals. Moderate mineralization - you want multifrequency or basic pulse induction (non-ground balancing PI) Severe mineralization - at some point a ground balancing PI (GBPI) is required. The above conditions grade from one into the other seamlessly. Fully submersible pulse induction metal detectors Here are the current mainline waterproof PI detector offerings: Bounty Hunter - no PI Garrett - Sea Hunter Mark II (PI) and ATX (GBPI) Fisher - no PI (one on the way?) Minelab - SDC 2300 (GBPI) Nokta/Makro - no PI Teknetics - no PI Tesoro - Sand Shark (PI) White's - Surfmaster Dual Field (PI) and TDI BeachHunter (GBPI) XP - No PI Finally, here are the key specifications for comparison: Fully submersible pulse induction metal detectors Waterproof VLF Metal Detectors Compared

The Aqua Manta has finally arrived in the form of the new Fisher Impulse AQ. The Manta has been officially named the Fisher Impulse AQ, a development that happened later in this very thread. It has also been revealed a gold prospecting model is under development. Go to the link above for the latest information and photos. Or quick jump to the Fisher Impulse AQ Specifications & Data & Fisher Impulse AU Specifications & Data pages. The information below remains for historical purposes. The challenge I have for Fisher or anyone else is to make a dry land ground balancing PI that weighs under 4 lbs yet is more powerful than a TDI SL. The alternative is waterproof but under 5 lbs. The price must be under US$2000.00 Waterproof Pulse Induction Metal Detectors Compared The Fisher Aqua Manta (edit 3/2019 now known as Impulse AQ) has been rumored for some time, and confirmed by First Texas as a project nearing completion. Prior threads: January 2015 New Fisher Pulse Induction January 2018 New First Texas PI Under Development June 2018 Aqua Manta Pulse Induction Beach Detector The long story short is this is a project by Alexandre Tartar. The Manta is most likely an offshoot and improvement on the orginal Eric Foster Goldscan circuit. Alexandre has built at least three major prototype devices before the rights were acquired by First Texas. The following photos and information is derived from this thread where the V3 prototype is sold. Here are the basic specs as described in advertisement (the seller is French and translating): "I sell a "prototype" Manta v3 There are only three copies of this detector and it is the best of three .... (See mantametaldetectors website) Pulse induction, works exclusively with mono coils to the beach, possibly for the land, but no ground control Calibrated for low conductors, gold and platinum, among other. Delay 7us of 17 volts more sensitive, deeper and faster than Deepstar Equipped with a coil, Manta, latest generation she has one month, the quietest and most efficient on the market, all brands included. (it will operate on TDI and Deepstar) Connector Type TDI, it accepts all coils (mono) of TDI / GPX Weight: 1.5 kg without battery that is worn at the belt headphone jack and on / off switch on the battery pack (lipo) supplied charger more than six hours of detection at full power. Carbon Rod Anderson + extra cane down braided nylon belt military style All the possible settings and need a good PI SAT speed, TX frequency, noise threshold, delay, volume, sensitivity.... The delay was 7us , lets see gold ends very thin rings, earrings, jewelry hollow that other detectors can not see and of course, the wholesale jewelry it goes deeper Ferrous recognition by a double beep well marked" What I find interesting is this note "Pulse induction, works exclusively with mono coils to the beach, possibly for the land, but no ground control" Yet here is the picture that accompanies the advertisement. Now remember this is from March 2016, almost three years ago. The prototype clearly has labels for ground controls... Alexandre Tartar Manta V3.0 prototype The control markings as seen above: Volume Threshold Sensitivity Sat Speed. Motion. (recovery speed) Tx Frequency (transmit frequency, usually to offset for EMI mitigation) Pulse Delay. GB Type (the shorter the pulse delay, the more sensitive to tiny metal and salt water) Ground Balance (usually a ground balance control, but ad says this is lacking?) Statements by First Texas suggest version 1 of the new machine is aimed at beach use and may not be suitable for land use (gold prospecting). That in turn makes me think work on the ground balance system is lagging and may be key to the future of the machine. Will it be beach only, or have a future for gold prospecting? I have to assume the unit will be competitive when it comes to the horsepower, or why bother? Until now the Eric Foster Deepstar is generally acknowledged as one of the deepest beach PI detector’s ever made. And the ad says “more sensitive, deeper and faster than Deepstar”. That being the case what really has my interest is the weight and compactness being displayed. The following photo collage from the advertisement shows the size of the control box and belt mounted battery: Alexandre Tartar Manta V3.0 prototype Granted the battery is belt mounted, but that is one tiny control box. I have to think that First Texas can slim down the circuit board and use a top notch integrated rechargeable battery and get this machine into a very compact package - hopefully waterproof and with wireless headphone capability built in. Well, that's about all I know about this one. This thread will collect any new information as it is available. This is one of a couple detectors I am watching so fingers crossed for a 2019 release. It is encouraging that Alexandre's original website at http://www.mantametaldetectors.com/ has been taken over by First Texas and is displaying this banner: Fisher Research Labs - New Pulse Induction metal detector COMING SOON!

Hi johndoe, I have to pick and choose what gets loaded to my servers. pdf files are huge, and I can't have people loading them up without review so that ability has now been locked down. I appreciate the desire to help but if you have pdfs you want to show people then link to the original source. I have replaced your file uploads with the links to the source material.

Thanks for the offer. I have already uploaded the User Guide and Advanced User Guide for the V3i and that will be it. I know third parties have put together pdf files on a range of items but this is not a matter of just collecting everything found on the internet and uploading it. I have copyright and fair use issues to consider and a lot of this stuff is pushing the limits. I see you uploaded some pdf files as attachments already, so I have blocked that capability. Pdf files are can be huge in size and I have server resources to look after. Anyway, I appreciate you are trying to help but I have more than I can handle right now. Thanks.

There was no adjustment for me going from the 11" coil to the 15" coil. Pinpoints the same, more or less in the middle of the coil. In the UK I was using a shovel to dig targets. They ended up in a small pile of dirt. I found I could use the 15" coil at a 45 degree angle to nose around in the pile and pinpoint off the tip of the coil. This worked so well I stopped using a pinpointer.

Good man, that's persistence! I admit to being a wimp and waiting for warmer weather.

Ah, but frequency matching is not everything. For starters, I suspect the Anfibio has a higher transmit voltage than the X-Terra and that alone could more than offset any performance issues revolving around coil matching. The fact is with Equinox Minelab has as much as admitted this multi coil approach was not the best. My recommendation is never let theory override observed performance in the field. The only way to really know for sure would be a serious set of tests. All we are going by is theory and opinion.

Added... Gold Districts of California The Tertiary Gravels of the Sierra Nevada of California

I offered an explanation in the second post on this thread.

Please link directly to things instead of telling people to go search for them. Videos can be posted here also. This is not a forum where such things are banned. Otherwise I have to take my time to go find them and add the links. Thanks! https://www.youtube.com/channel/UC9kem8woYGfXIlDBTfbF9cw

And here is an Amazon link to the book or one like it. And here is a website I found while looking for the book that has a detailed history of several Alaskan roadhouses. Thanks George, great subject.

I suppose you could email Minelab and ask. Hades (welcome to the forum) is on the right track. There are membranes that allow air to pass but not water. This is probably a pressure equalization vent? I am just guessing. Here is a link to the page for Gore Portable Electronic Vents.