Mark Tillman

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Mark Tillman last won the day on June 20 2016

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About Mark Tillman

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    Bagdad, Arizona
  1. Yeah I guess they would rather sell a new battery than repair one. Someone else might be able to troubleshoot the circuit but it's beyond my capability so I'll be looking to pick up another one.
  2. Just an update to my original question. I did contact Mine Lab Americas and spoke to one of the reps. She informed me that the batteries were not repairable She also was able to check the serial number on the unit to verify that it was a genuine Mine Lab as well as the manufacture date. This turned out to be something of a story in itself as there was initially some concern on ML's part that the detector might have been a counterfeit (since I had bought the detector used, this had me a bit concerned). Anyway, it was reassuring to find out that it was genuine although a bit disappointing to find that the battery was not repairable by the factory. Earlier, I had pulled the 8 screws from the front and back of the battery in order to slide the PCB with the 8 Lithium batteries ( 4 per side) out of the case. I didn't see anything obviously wrong like a loose or broken connection so it looks like I'll be buying another battery soon or maybe instead try one of the aftermarket power packs with amplifiers such as the Gold Screamer or something similar.
  3. Hi Chris, I will give that a shot although it's probably not still under ML warranty. Considering the price of a new battery, I wouldn't mind so much spending a few dollars to have a backup.
  4. I have a spare battery for my MineLab GPX 4500 that I assume to have a bad amplifier circuit. The battery can be charged up and will allow me to run the detector but without amplifying the audio. As I bought the detector used, I was unaware of what the audio was supposed to sound like so I didn't discover this problem until I had a chance to try the detector using it against a different battery (another one of the neat things about attending the hands on training sessions at ICMJ's Gold Shows in Placerville). Anyway, so I have this spare battery and I'm wondering if the amplifier circuit is something that can be easily repaired since it would be nice to have a 2nd battery for those extended trips?
  5. Dan and Roughwater, Sorry for this late reply back-vacation plans and travel kept me off line for a while. I did pick up a second mono coil; going with Nugget Finder's new 13x17 inch Evolution model coil. My initial opinion of the coil is that it's remarkably sensitive for it's size. And having used the 8in mono almost exclusively since getting into gold detecting, the larger size sure is nice when it comes to covering more ground. I'm looking forward to using it in some of the more open areas where the size and greater depth capability should prove more useful. Thanks for the comments.
  6. My detector is a ML GPX-4500 model and I've been using a round 8" mono Commander coil as my primary coil. I have two DD coils but they seldom see any use. I would like to purchase at least one and perhaps two larger coils to add to my limited arsenal and I'm looking at something like a 14" elliptical mono or a 14" round mono coil to start with. From my understanding, the 14" elliptical (14"x9") coil would really not give me much more ground penetrating capability (comparable to a 9" round coil) so the 14" round might be the better choice. However, there's been numerous occasions when I would have liked to have had an elliptical coil for reaching into narrow spaces while working creek beds and such so I consider coil shape an important factor as well. So far, I've confined my detecting to areas that stay within the limitations of the 8" coil but I would like to have a coil capable of working more open terrain with ground measuring a foot or more so my first question is 'what would be a good all around coil to go with if I were to purchase just one additional coil?' Second, if I were to purchase a second coil, what would that one be? And finally, if you were limited to using only one coil, what coil do you think would see the most use? I mentioned the 14" search coils above, but I'm not limiting myself to just that size and would also consider going either larger or smaller based on recommendations. Thanks, Mark Tillman
  7. Well I finally found my first metal detecting 'nugget' yesterday afternoon. I'm going to call it my Easter nugget although weighing only 0.25 grams, it might not qualify as a nugget by some peoples standards. I found it in a narrow gulch not too far from my home here. When I first swept the coil (was using the 8in commander mono coil) over the target, I got a signal indicating a metal object. but it appeared that I had lost the target after digging down maybe 5-6 inches. Figuring that I had already pulled the target out of the ground, I went back over the spoils pile but no signal there either. I thought my mind might have been playing tricks on me and that maybe I had mistaken a hot rock for a metal object but before giving up I tried dropping the coil to the bottom of the hole and there it was again although not as loud as when I first heard it. I pulled maybe3 or 4 more scoops of material out of the hole before locating the small, very flattened piece of dull yellow gold and my first bit of gold found metal had only taken me the last year and a half to do so but then no one ever said it was going to be easy! The difference in signal loudness had me a bit puzzled at first, I'm guessing there might have been something of a halo effect in play here.
  8. Geowizard, I understand about slowing the motion speed down to improve threshold stability. Running in deep mode with the motion speed set to very slow seems to provide a very stable threshold. For where I've been currently detecting, this has turned out to be my preferred setting since other settings like sensitive extra, sharp, or sensitive smooth all seem to give too many false signals or the threshold lacks stability. I'm going to try your suggestion regarding burying small pieces of aluminum at different depths and record the various responses in a field log. I've been keeping a journal already of the locations I've detected (mainly to keep track of the various settings) so no doubt this will prove instructive. It was my impression that the manual tune feature of the detector was primarily used to eliminate or reduce EMI by allowing you to fine tune the channel selection process after first completing an auto tune? I'm thinking that you meant to say that lower numbered channels (assuming they corresponded to lower frequency and hence longer wavelength signals) would give an improvement in search depth but I would be interested in knowing if this is not the case. A friend recommended that I run my detector's ground balance in 'fixed' mode and just be careful to check the ground balance frequently and I've been doing that for a little while now. Seems to work well doing this. I really would like to get out to some other areas to detect so I can get a better understanding of different soil mineralization. I was able to get up to this year's ICMJ Gold show and did some detecting during the placer training class. It was interesting to note how the soil mineralization there seemed almost benign in comparison to some of the soils over here. Watching some of the guys doing there initial adjustments and they really didn't seem too worried about ground balancing. On the other hand, it was a surprise to see how the EMI from quads operating in close proximity could really interfere with detecting in an area. Mark Tillman
  9. It sounds like you had a pretty decent day there Chris and that SDC sounds capable of finding some pretty small nuggets in the hand of a good operator. I'm not quite ready to declare my lack of success detecting here due to my 'not swinging my search coil over any gold' (I'm not that confident yet, I'm more inclined to think that I've probably missed some of the more subtle changes in signal that would indicate a gold target below and I due tend to listen for those very faint changes in threshold) but a point certainly worth emphasizing in that I can't expect to be successful if I don't manage to swing my search coil over a detectable nugget in the first place. Thinking about it now, I probably deluded myself into thinking that lode mines employing arrastras was synonymous with detectable nuggets and forgetting that arrastras employed mercury which would have suggested gold on a scale possibly below the limits of detection for most detectors. Thanks guys for the helpful comments and Geowizard, I'll give your suggestions for determining my 4500's detection limits a try. I'm not an electronic engineer but your comments on the time domain of a detector as a function of nugget depth sure sounds like a good explanation. I'll keep that point in mind next time I'm making my initial adjustments.
  10. Thanks for your comments Chris. I am interested in prospecting more areas and have managed a trip or two to areas like Gold Basin but without club connections, I get the impression that most of the best areas are already claimed up so joining one of the local clubs in this part of the state makes sense. The western edge of the Eureka District did have a few small lode type gold mines but like you said, they may not have produced gold of sufficient size for a metal detector to detect. A couple of these old gold mines employed arrastras for grinding so I was hoping that the free milling nature of the ore also suggested a mine capable of producing at least some small nuggets but I sure haven't found anything to substantiate this notion either. Maybe wishful thinking? I've been using a small gold test nugget (about 1 dwt in weight) for setting the detector's gain-I probably should spend a bit more time running comparisons between the different 'soil timing' and 'search' modes. I
  11. I'm running a GPX-4500 detector with the 8 inch Commander mono-coil. Lately, I've found that I'm getting the most stable threshold running the detector in 'deep' search mode with soil timing set to 'sharp'. Gain remains around 8 or 9 and I generally leave stabilizer set at the factory preset of 10 or sometimes drop it by a point. My question is, would I (speaking generally) be better off running my soil timing in sensitive extra when running in deep search mode? Also, since the detector defaults to a very slow sweep speed when in deep mode, exactly how slow should I be swinging my search coil, assuming a normal sweep speed of 1.5-2 ft/sec? Pretty basic questions here but I haven't had an opportunity to detect much with more experienced operators. I would describe most of the ground mineralization where I detect (the Eureka District here in western AZ) to be of average mineralization but then again, I've not detected a wide variety of locations to base this assumption on. A good deal of the metal targets I've been digging lately appear to be rather small (fragments of lead bullets, iron tacks down to 0.23 gram in weight, etc) so I have some confidence that my settings are at least not out in left field.
  12. Is your truck 2wd or 4wd? Just wondering since it would seem like you should be able to get closer than 10 miles to where you want to prospect. Of course areas like the Grand Canyon and the Barry Goldwater Bombing range could prove rather inaccessible but the geology would be wrong for the GC and BGBR wouldn't seem worth the risk. I did visit one mine in the Bradshaw Mts that required hiking just about 5 miles but that was only because the forest service road accessing the mine was closed off by private property holders....same old story.
  13. Well I sure know a good deal more about Rokon trail bikes than I did before I asked my initial question so thanks Gary and Gold Seeker for sharing your knowledge and experience with the bikes. I've been thinking about getting one to use primarily for prospecting and visiting old mine sites scattered around the Arizona outback so the fact that they're rather slow wouldn't generally be a problem although it might limit my using it to commute to and from my work (lots of folks around here use quads to commute to and from work so the Rokon would be at something of a disadvantage here). Gary, I like the way you were able to secure your gear to your bike as I assume you can squeeze one of the smaller size dry washers into the plastic case on the back which would suffice for sampling purposes. I run a medium size Gold Buddy DW which just fits into that size case excluding the blower motor and flex hose. For myself, I'm thinking that the most practical approach would be to use the bike to get myself and my metal detector into an area of interest and then use the detector as a general prospecting tool to help locate potential spots to dry wash. Using the metal detector to pinpoint possible spots worked out well for us last spring when my girlfriend; using her Gold Bug 2, was able to pinpoint a good spot for dry washing whereas we recovered just over 1.5 grams of gold over two days of dry washing. Not a lot of gold for the amount of work involved but probably a realistic return for the area. This area is also somewhat off the beaten path and the first time I visited the location, I had to hike in about 3 miles since the road was washed out. Since then, we've managed to find an alternate route into the area that gets us within a quarter mile of where we set up our dry washer...easy walking distance.
  14. They do seem like they would be able to handle more extreme terrain than the normal 4wd quad while quads seem inherently easier to ride for the average person. As far as how much gear one could pack into an area with either of these 'mechanical mules', I would guess you would have to give the edge to the quad. Still I would have to admit that something along the line of Gary's machine does have a bit more appeal to me but until I can really justify their rather steep price, I'll be constrained by the limits of how much I can pack in on my back and the range my two feet can carry me. Thanks for your comments Bob. Mark Tillman
  15. Gary M adds: "Just an FYI… if you ever decide you want to join me, all I ask is that you brush up on your dirt bike skills, as this is what you'll be riding. So far I have two of these. I call them my little mechanical mules. They'll go just about anywhere, they don't need feeding or watering, they don't kick, and best of all they're not stubborn! :D" Gary do you compare those Rokon trail bikes with something like a Quad for prospecting? I've looked at Rokons online but they seem pretty pricey. Can they really climb 60 degree slopes like the manufacture claims? I also visit areas well off the beaten path but usually under my own power but I sure could see the advantages to having one of those 'mechanical mules'.