GB_Amateur

As far as handles go, the pic in Steve's review: http://www.detectorprospector.com/gold-prospecting-equipment/whites-tdi-pulse-induction-metal-detector.htm of the original Pulse Scan TDI shows the "I-handle" that apparently was kept for the TDI Pro model. Oh, and BTW, here's one one of the original models on ebay: http://www.ebay.com/itm/whites-tdi-metal-detector-/232135586672?hash=item360c5bf370:g:VYsAAOSw4GVYH3L5 That ad claims the original is more sensitive ("slightly deeper") than the later models. I don't know what evidence there is for that claim but I've certainly heard/read similar regarding the TDI Pro model compared to the TDI/SL. I also wonder how much all this has to do with the battery voltage. Surprisingly (to me), again from what I've read, none of the TDI's has a voltage regulator on the power supply (batteries) and thus will perform hotter if run at higher voltage. (See Ridge Runner's suggestion above, for example.) So, bottom line, how much does the perceived sensitivity difference between the models simply depend on what voltage they are run at?

Aha! My SPP labels (one on either side of control box) are actually just put over the top of previous (stencilled painted) labels. When I pealed off one of the SPP labels it says "GMT SUPER PULSE" followed by an e-mail address, web address, and phone number in UAE. Below that it says "Mfd for ASSOCIATED GROUP, United Arab Emirates" (followed by a White's USA copyright). So more evidence of your explanation, Matt.

Yes, RR, and not only for a PI detector. This is the easiest detector to set-up-and-go that I own -- the other two being IB/VLF's which aren't that difficult, either. I have no experience with other PI's so I can't speak in terms of relative to other PI detectors. The other thing I particularly appreciate with the TDI/SPP -- and this is effectively true of the TDI/SL because it's the same detector with the exception of one switch and one control (variable resistor?) component -- is just how light weight it is. This is particularly true when used in conjunction with the smaller coils. Just weighed mine (with 220 mm "flying saucer" coil I recently bought at White's online Garage Sale) and including the loaded battery pack and a handle I added (not necessary in general but helps with some heavier coils) it came in at 3.45 lb. Without the additional handle and a Miner John 5 in X 9 in coil I recall it comes in at slightly over 3 lb. Of course one 'price' of lighter weight is shorter run time / battery life. The pack with the 8x AAs weighs 0.61 lb and the factory stock NiMH pack slightly more at 0.65 lb. A full day of detecting is about 2 battery packs worth.

Actually SPP stands for Sierra Pulse Pro. I seem to recall seeing 'SSP' ('Sierra Super Pulse'?) referencing this detector in the past. I don't know if that was an official name or maybe just a mistake.

From Wikipedia: In many instances, high-end fashion jewelry has achieved a "collectible" status, and increases in value over time. Today, there is a substantial secondary market for vintage fashion jewelry. The main collecting market is for 'signed pieces', that is pieces which have the maker's mark, usually stamped on the reverse. Amongst the most sought after are Miriam Haskell, Coro, Butler and Wilson, Crown Trifari, and Sphinx. However, there is also demand for good quality 'unsigned' pieces, especially if they are of an unusual design. It makes a better story to contrast true finds with 'worthless' items, and in fact much of costume jewelry has little value today. However, if you watch PBS's Antiques Roadshow you know that some jewelry which was made from common materials and sold inexpensively from the 1920's to late 1950's does carry value today amongst collectors. Bottom line is: don't just throw out items because they aren't made of precious metals. Do a bit of research first.

I think extra gaskets will also do the trick. I've used my Fisher GBPro lower rod interchangeably with the TDI/SPP lower rod (after just a tiny bit of filing) and I've put a Coiltek 6 inch diameter DD on my GBPro. The latter required extra gaskets (that I bought at the hardware store) but it worked fine. Maybe the heavier, torquier larger coils are more of a problem, though. I don't have any large Coilteks so I can't say anything about that.

Only way to go? There are at least a dozen detectors on the market that can perform well in multiple areas of detecting, and for any given area of detecting there is one (or more) specialty detector that can stand above most/all for that reason -- because it is a unit built to specialize in one area. No doubt the Deus has proven itself among the best. Is it the one-and-only best? Use your good judgement and your answer will agree with mine.

Wow, wow, wow. I don't know how I missed this in the past but what an informative article! I suppose I would have figured this out with enough experience (and expense, as in buying enough detectors). The modern (and I guess this goes back 1 1/2 to 2 1/2 decades) detector depends so much on microprocessors and their associated software. That's a good thing in one way because of its expanse of potential settings and capabilities, but sometimes a bad thing because the true strengths and (especially) weaknesses of these methods tend to be hidden from the user, unlike in the (admittedly ideal = unrealistic) analog days. Apparently the 'best' detectors give us both, and leave it up to us to decide which and when to use. But one thing is true about all detectors since before most of us were born: the more you understand about your detector, whether by reading or talking to experts, or especially learning by your own experience, the more success you will have. Thanks, Steve. I learned some more by reading and now can't wait to experience it.

Thanks, CF. All sounds like good advice / things to try. Regarding ground balancing, I've never run in tracking. I always use Auto (known as "Grab" by some manufacturers). Should I be using tracking? Interestingly, yesterday with the 6" Digger coil it ground balanced at 34, very similar to what I previously have gotten with the stock (8" 7.5kHz round concentric). So now I'm thinking my previous observation of GB at 9 was somehow erroneous, either misreading my detector or balancing over metal or ?? It would seem to me that turning down sensitivity lowers response to all metals -- those I want to dig and those I don't. So if that reduces wrap-around at the cost of losing deep (good) signals, then maybe I should learn to live with the wrap-around? I've done air testing with a gain of 15 (factory setting) and a gain of 24 and it's clear that (at least in air) depth of all metals increases with gain more/less the same (i.e. max detectable depth increase/decrease is same for desirable metals and undesirable ones). I usually run gain=24 but yesterday I used gain=27 and didn't notice much difference than previous trips to the same (iron-infested) location. OTOH, I didn't find much yesterday.... One thing I wonder aloud about: are some detectors configured to 'protect' the user by limiting gain, while others are distributed with the "we'll give you plenty of rope and you decide how not to hang yourself" principle? An example of the latter *might* be the Fisher f75 (which I don't own nor have ever used, but read plenty about it) where you can use things like "boost process" and turn Digital Shielding Technology (D.S.T.) off to get maximum sensitivity at the expense of an increase/decrease in noise (and possibly annoyance/frustration).

This is primarily a coin and jewelry hunting topic, I think. Getting more experience with different detectors, I'm wondering if I'm seeing a common (but hopefully not guaranteed) issue. What I'm referring to is called 'wrap-around' and I'm sure it has other names. Basically the low end of the induction balance (IB) ID scale is low conductivity iron and high end is pure silver. But sometimes with iron you get a high ID, usually in conjunction with the low ID. I've had this happen on three detectors but don't remember it on a 4th. The three are: White's DFX-300 w/ 950 concentric coil (least experience), Teknetics Gamma 6000 w/ egg-shaped conc. coil (intermediate experience), and Minelab X-Terra 705 w/ both 7.5 kHz 8.5" round conc. stock coil and Coiltek 3.0 kHz 6" round DD "Digger". I don't remember this problem with my Gold Bug Pro with any coil. I go into detail here with the 705 because I've used it the most in iron infested sites. The lowest ID on the 705 is -8 and the highest is 48. (All even numbers except 0 in between occur but never odd numbers -- by design.) Iron is anything below 0; high conductive coins (Cu and Ag alloys) are above 35 (usually) with silver dollar being highest US coin at 46. (Don't know what a pure silver round would read, maybe 48, but who drops those?? ) In the US Midwest we mostly have moderately low iron content (at least compared to US West) -- may be exceptions in iron mining areas like Minnesota and Michigan Upper Peninsula. I've seen phase auto at 35 with the 7.5kHz coil and 8 or 9 with 3 kHz "Digger" (don't know why the disparity...). I run max tones (~30 of them?) in "Coin and Jewelry" discriminate and alternate between "all metal" and notching Off below 0 and also notching Off 48. Note: this detector has a prospect mode but that operates quite differently and I haven't used it for hunting coins, although I see that some have. Even with the notching described above I get 46's and even 44's on iron targets. In all metal I can hear the jumping between iron ID's and high conductive ID's, but this can (and does!) happen when you're going over a coin near a nail, for example. The hope was that I could listen to tones and not have to look at the screen, but that doesn't seem to work well for me in the iron infested parks I hunt. I'm sure with more experience (and, yes, I've read Randy Horton's "Understanding the X-Terra" multiple times) I'll get better, but I still find myself, even in max tones, having to look down at the screen way more than I would like. So I guess I have a two part question: 1) is this an inherent problem in all coin hunting and multipurpose IB detectors, and if not, which ones are immune to it? 2) Do you have tricks, besides over-notching, to work around this problem? I've found enough old coins that I don't want to notch out halves (ID=44), because I know, although rare, they are out there. Lastly, I'm not interested in modern coins, although those come with the territory. So far I've found old coins at shallow depths (4 inches or less) and none deeper, although I'm sure they are there. I dig lots of pulltabs (square but mostly ring & beavertails) and don't mind that. There are coins in that zone and I'm willing to put up with the Al in order to find them.

Interesting. Where do you set the V-break? Leave at 0? Normally below VID=40 is considered ferrous/iron but of course some non-ferrous (like small gold) will come in below that. Are you saying your trick eliminates all iron or just the worst, lowest conductivity (e.g. below VID=20)? I have some iron infested sites I'd like to try this on (but not the next couple weekends as I'm out-of-town for both )

I also have a Garrett Carrot (ProPointer AT) and wonder how any coin hunter used to get along without a hand-held pinpointer. I'm pretty sure (from what I've read and also from experience) that the sensitive part of the shaft is about 1/2 inch (~1 cm) up from the tip. In fact it's said to be even more sensitive than the tip! When I get a signal I lay the GC on its side and hunt around the ground with the side of the shaft, assuming 1/2 inch up is the sweetspot, to find the maximum response (if the item is close enough to the surface to give a response). One nice feature of the GC that it took me a long time to realize is that you can desensitize by just keying the switch. I run mine on gain=3 (the highest) and desensitize as I get closer to the target when digging. I agree that when in a hole it's not always easy to know if its the tip or the side that is picking up the target, but by desensitizing I can almost always distinguish which. And sometimes with a really large target (not a coin) I have to change the gain to 1 and then desensitize. But that's pretty rare. Also agree that multiple targets in a hole can lead to confusion, which is one more reason why I (and everyone else that I've read or learned from) assumes that pulling one item out of a hole doesn't mean you're done. Here, though, I use the main detector for a second sweep because often the remaining target (picked up by the pinpointer) is a junk target, and I need the discrimination of the main detector to tell me that. On a lucky day it's the junk I pulled out first and now the desirable object gives a much cleaner signal and VID to finish up on. Found a 1920 Merc after digging a nearby nail out of the ground last week. I've never had another pinpointer so can't compare or contrast. I just know I'd be lost without mine.

Good catch. (And nice find, ...maine.) All but the first year (1859) had the shield and it (along with 1860-1863 and some of the 1864) were Nickel-Copper alloy. I've not found any of the Ni-Cu (the earlier Flying Eagles also were of this alloy) but have one in my test set for determining VID. I've now found three of the standard alloy (95% Cu, remainder tin and zinc) Indian cents and all came out of the ground with that green color. In fact, without seeing either obverse or reverse (which are usually caked in dirt) if I see the green rim I feel like I've got something good. It's interesting that the Wheat cents I've found (only two so far: 1945 and 1953-D) weren't green. They have close to the same alloy -- 95% copper -- but over the years the remaining alloys have been listed as tin and zinc. I don't know if the relative amounts of the two minor alloys have been held to tight tolerance or whether those two vary over the map. So possibly the green color depends upon this. Saying all that, maybe it's the amount of time in the ground, and even the chemical makeup of the dirt and amount of moisture that determine the color. The worst condition copper Memorial I've found came out of a bedrock crack in a creek, so that indicates that water is a contributor. It's currently at ~80% of its birth weight. It actually is colored a mottled (but not pretty) combination of green, reddish-brown, and black. (Note I haven't been talking about the 1982 and later "Stinkin' Zincolns" which deteriorate almost as badly and as quickly as a tossed aside banana peel.)

Add my name to the growing list of small coil lovers. (I don't have an XP/Deus, though.) If you live where there is modest to little trash (for whatever reason) then large coils are great. But when there are tons of nails, etc. I just drive myself crazy hearing all the trash. Most/all detectors are most sensitive to iron, I think because its magnetic (especially) and conductive properties combined. It's very abundant in the earth's crust (3rd most common by weight after Oxygen and Silicon?) meaning its inexpensive, also very strong, and as such has been used for centuries as a building material. There are lots of software (and hardware) tricks to 'ignore' iron, but they cost, sometimes severely, in sensitivity to the metals we want to hear/find. AFAIK, to date the best solution in iron infested locations is to use a small coil to minimize the amount of trash in its zone of influence. If that means extra sweeps of the 'broom', I can live with that. IMO it's worth it. And reducing the overall weight (preferably with an associated adjustment in balance) is a nice perk. In my area I use small coils 90% of the time, and that's not because I don't have intermediate to large ones. It's just what works.

Very impressive finds (139 Wheats, etc.)! All I saw in your post was 'TDI' -- which model? Also, if you don't mind, are you able to reject the old ring-tab (sometimes with beaver tail still attached) or do you end up digging them? Those can be deep since last made in 1975. I find way more of those than steel (beer) bottle caps, the new 'square' tabs, and aluminum screw caps combined. (That's with my VLF's, but I do have a TDI/SPP which I got for hunting native gold in areas with large hot rock populations but I'm not averse to using it in parks, especially after reading about your successes.)

Very nice find. I'm curious about the weight. According to The Redbook when minted this had a mass of 2.5 g. Can you put it on a scale and see how much is left? In my part of Indiana the copper coins get dissolved pretty badly from (I'm guessing) acid in the soil. I didn't expect silver to suffer the same fate. This holds true for Cu pennies caught in creek bedrock cracks. Of course coins wear when in general circulation so the difference from 2.5 g is only going to be an upper limit on how much material was lost in the river.

If you're serious, strongly consider buying these guys' (George Overton and Carl Moreland = Geotech) book titled Inside the Metal Detector ($29 online). I don't like to make superlative statements in general and especially about things I'm not expert in, but if there is a book on the subject that is even close to this one I'll be surprised. There are a handful of do-it-yourself detectors here and they tell you *why* they work on top of it. Even if you're not looking to DIY (I'm not) this book is easily worth more than the online price.

CORS: http://corscoils.com/index.php and NEL: http://nel-coils.com/index.php/en/ also make coils for the X-terra. From my web-searching it appears as though CORS has a much greater selection, including three at 3.0 kHz, six at 7.5 kHz, and four at 18.75 kHz. Having said all that, I don't have any CORS coils (yet) and the only NEL coil I have is the 15"x15" DD Attack, and that one is for my Fisher Gold Bug Pro. (Further, I've only tested it; haven't put it out in the real world yet.) Others here should be able to give good feedback on these brands. As far as not wanting to change coils to change frequencies, I don't see why this would be a big deal, other than the extra weight if you travel far from your vehicle. I change coils in the field quite often. And if you have a high-freq coil for native gold hunting and a mid- or low-freq for coins/jewelry/etc., how often in one day will you want to change frequencies?

Yes, but ironically the coils listed in the manual's specs aren't the coils shown on the manual's cover. I have the 150 mm round Super Pulse coil (as you know since you sold it to me as part of a used SPP package) and I've had it cracked open -- it is a mono coil. And I'm pretty sure the 12 inch open structure coil that also came standard with the Sierra model is mono (The "Aussie Mono") although it just says "Pulse Scan TDI" on the coil housing so maybe not.... Thanks to this thread (no sarcasm intended :) I bought one of the 950 style coils in this Garage Sale. I couldn't pass up the great price, even if it only turns out to be a collectors item for me.

I don't understand this. You imply that the average of the long and short axes represents the performance of a coil sufficiently well so as to be able to claim two different shaped coils are equivalent (or close to equivalent) in perforamance when these derived quantities match. I've never heard this. Or am I misinterpreting what you said?

The 95::5 ratio doesn't surprise me. If you look at a lot of fields of interest I suspect you will find some, even many, with similar numbers to this. Some people have bad memories of school and other learning experiences. Some of us can't get enough (and obviously you are in this second group). I'm surprised at the author's response. I hope (and am pretty confident) that person is the exception. In my experience when I get an answer such as this is that the person is hiding something, and usually it is a lack of knowledge, lack of confidence, and lack of courage to admit such. Since I buy a lot of books too, I'm curious as to who that author was. In reality, without hearing both sides of the story, it's a bit dangerous to draw too strong of a conclusion and I understand why you don't post the name here. (I wouldn't if I were in your shoes.) OTOH, I wouldn't mind if you sent me a message with the name.

Clear Creek which winds its way from the high Rockies (east side of Continental Divide) all the way down through Denver has not only produced profitable gold but also currently has parts where open (i.e. to the public) prospecting is permitted. Here are a couple listed on this (yes, Steve's) site: http://www.ci.wheatridge.co.us/1184/Gold-Panning http://jeffco.us/open-space/activities/gold-prospecting/ In June I visited the Wheatridge site. The creek flow at that time was still fairly strong so I was unable to get to the northside, but that is where the tailings are located. You may be able to ford the creek now, but if you park at the public parking area on the East side of Youngfield you can walk under the I-70 bridges along the north side of the creek and access the main area that way. (It's not an easy traverse if you're carrying a detector in your hands, though. I recommend a walking stick to assist you.) I'm vaguely familiar with the 10 miles further west (second link) but didn't visit there recently. My recollection is that large scale commercial dredging was done there in the past. That alone ought to indicate it's worth checking out if you have time. I was told (by reliable sources) that metal detecting in Wheatridge city parks (first link above) requires a permit. I don't know if this applies to the above gold-panning site. To be on the safe side, if you're doing more than collecting paydirt to pan, you might want to look into that, although it would probably take a letter-of-the-law person to object to someone using one in the placer tailings. These laws are typically written (agree or not) to prevent people from damaging public greenspace (e.g. manicured city parks). Good hunting!

OK, I guess I don't get it. If the government takes the strong arm approach and says "here's the law..., it's our right..., you are required to comply..." we get up in arms. If they ask our permission we ridicule them.

There is another option which isn't quite as sound but also is easier to reverse: tape. I use Scotch Super 33 vinyl electrical tape (3/4 in width -- far the most common) which is widely available at hardware and big box lumberyards. One key technique to remember when using vinyl tape: don't stretch it! If you do it will find a way to unstretch with time, often costing you your seal. Even when done carefully the tape will eventually wear down, but I've got tens of hours on my Gold Bug Pro 5 inch round and it's still tight. Silicone sealant is great and once you're sure you want to go that direction then I agree. Its biggest problem is that sometimes it's too great, as in being difficult to remove. You can usually break attached parts loose by cutting with a knife, but getting all the old silicone off is a real pain, as in nearly impossible with some surfaces without damaging them. I once asked a GE chemical engineer (GE has a industrial brand called 'RTV' but also supplies the same stuff for home do-it-yourselfers which you also can get at hardware and lumberyards) how to remove RTV. I was specifically looking for a solvent. He said there was none known, but one solution that some have used is to soak in toluene or xylene, which causes it to expand and weaken. I've tried that but you still have to scrape the surface in the end. (You likely know those two compounds need to be handled carefully as they are carcinogens, although probably not so much so with only occasional use in well-ventilated areas. Also a concern is whether they attack the plastic you're trying to clean....) Another issue with silicone is that it doesn't adhere to all plastics. In fact it's not great with some coil housings and covers. (It seems to work well with some plastic compounds used for that purpose, but not all.) So experiment if you can. An even better sealant (IMO) for some coil housings and covers is Rust-oleum's LeakSeal (similar to "as seen on TV" Flex Seal but about half the cost!) because it has a petroleum base, unlike silicone which is, in my experience, either acetic acid or methanol based. That helps by mildly attacking the plastic surface leading to a better seal. Bottom line is that I agree with using sealants if you're making a permanent bond. Otherwise don't trim your fingernails because you'll need them (plus time) to scrape off the cured sealant, preferably during some time-shared task such watching one of the many treasure shows on TV this fall and winter.

Hear yuh there, strick. I've heard and read lots of complaints of people finding ring&beaver-tail pop-tabs. I love 'em, especially when the ratio of those to 'square tabs' (modern pop-tabs) is high. It's strong evidence of one of two things: 1) minimal amount of detecting since mid-late 70's when they fell out of favor in the aluminum can business, or 2) detectorists failing to dig items in their discrimination region. Either way there should be a lot of juicy targets remaining in old sites. Best wishes in your hunts.