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Last Post 16 Nov 2020 12:04 PM by  ROBERT MARTINEZ
GMT
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ROBERT MARTINEZ
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13 Jun 2020 11:02 AM
    I recently purchased a Whites GMT. It came with the 6"x9" Double D coil and a 8"x14" Sierra Gold Max coil. I took it out to the gpaa claims in the Morristown area. Towards the end of my testing and it was getting hot. I put the big coil on. I got up on this hill overlooking a wash and started detecting. I got this positive zip zip sound. I scraped the loose gravel with my boot and still got a good signal. I scraped down another 2-2 1/2" and found a .04 gram flake of lead. I wish now I had started with that coil. Just thought I would share that. I was set at 2.5 gain and around 2 on s.a.t. the ground was balanced around 60 if I remember right. The other coil balanced around 70-71. I had the double D coil set around 3-4 gain and 2 1/2-3 s.a.t. Later when I learn this detector I'll increase the gain.
    ROBERT MARTINEZ
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    05 Jul 2020 04:36 PM
    So today I went out to Kings claim North of Morristown and tried out the 8" x 14" coil on my GMT. I can't believe how tiny the targets it can detect. I spent 7 hours detecting and found many junk targets. And in that 7 hours I didn't wander very far. It takes awhile to detect a section of ground. Lots of birdshot bits of wire mesh etc. As I was leaving I realized I didn't test the depth of the coil. Most of the targets I found were surface finds and a few around 3" deep. So I stopped on the south end of kings and buried a .7 gram piece of old lead about 3 plus inches down. I set the detector with a low threshold in my headphones and no sensitivity or sat. I could detect the target easily. I then dug up the target and buried it 6.5 inches down and passed the coil over the target again with no sensitivity. It was on the edge of detection. I turned the sat to 3 and the sensitivity to 5. It blasted loud in the headphones. I could have buried it lower but I felt comfortable that I wasn't missing targets when I had been detecting earlier. I just realized I never used the audio boost. I was really surprised that I could detect the target with no sensitivity. Hope this helps someone out there. Good luck detecting. ☺
    ROBERT MARTINEZ
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    08 Aug 2020 01:33 PM
    So the other day I was testing a receiver/transmitter bluetooth thing I got off of Amazon on my GMT. I had a good set of Bluetooth ear buds already. The very first thing I noticed is that I was able to turn the threshold way lower than I could with my regular wired headphones. I was able to adjust the gain or sensitivity higher before I could hear instability sounds. I was able to hear my .04 gram test nugget loud. I read the directions that came with the detector and it touches on the headphone subject but really doesn't explain why they're important. Check out high ohm headphones with your detector to see which ones sound the best. My ear buds are also clear sounding and not muffled. I plan to wear shooting ear muffs to help with wind while using these. Hope this helps someone.
    ROBERT MARTINEZ
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    25 Sep 2020 12:49 PM
    So when I used my Bluetooth ear buds I noticed that I could hear everything. I had to turn the volume down on the ear buds so a buried tin can didn't make me deaf. I then set up the detector to the just barely but audible threshold and ground balanced while my gain was around 5. I used the SAT to around 2.5 - 3. Hope this helps anyone.
    ROBERT MARTINEZ
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    28 Oct 2020 08:00 AM
    When turning on my GMT, and I noticed it works basically the same with my gold bug pro and xterra 70, I have my SAT around 3 and I'll set the detector to around 7 while the detector is held in the air. I then slowly turn up the threshold until I just start to get a sound. Sometimes it's a sputtering noise then I turn it up a tiny bit more so that I know the threshold will be audible when I ground balance. By the way my headphones are set at a comfortable level when I'm doing this. I ground balance in a large area around me to find the least ground balance signal and balance to that area. Then I see how stable the detective is as I slowly sweep the coil back and forth. If it's noisy where I can't hear the sound the threshold made when I first set it then I lower the gain until I can distinguish the ground noises from the threshold and constantly ground balance as I do this. Just figured I would pass that on. Hope it helps.
    ROBERT MARTINEZ
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    11 Nov 2020 12:54 PM
    I went out to the claims this past weekend. The first thing I noticed is that the GMT concentric 6" coil reads the ground around 62-65. The 5"x9" coil reads it at 71-72. Also the concentric coil required higher S.A.T. speeds. I thought I would have to swing faster but the ideal speed was actually slower. The overlap has to be closer and the ground balance I figured out manually balancing has to be faster up and down to outrun the S.A.T. I had to flip into fast track to figure out where to start the manual ground balance. The coil sees very tiny targets easily in the ground but when you get them out of the ground that's a whole nother thing. I had to flip into signal boost a few times. I guess I need to figure that out.
    ROBERT MARTINEZ
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    13 Nov 2020 02:21 PM
    I came across this story about a guy finding a 27oz nugget out by one of my friends claim. I ordered a 27oz lead fishing weight to test my detector settings on. The nugget was found with a VLF detector 2' deep. Figured I would bury the weight and listen to what I should be listening for. Just doing air tests, I can only get about 1'6" away from the coil. I have a concentric 9" 7khz coil and I put the 14" elliptical concentric on my GMT and my 6"concentric coil and the same results. I know that the air tests are around half the distance you can actually detect. Does this sound like a fish story using a vlf detector? Maybe it was a pulse induction detector. But either way I was surprised that the huge heavy weight was so hard to detect. And gold will be harder to hear even more. Very interesting test. I'm still going to bury it and find out the limit of my detectors.
    Leo Lorenz
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    15 Nov 2020 12:33 AM
    But you need to take into consideration that a target in the ground builds up a "halo effect" around that target which allows it to be seen at greater depths than an air test does. This affects your detectors sensitivity.
    ROBERT MARTINEZ
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    16 Nov 2020 12:04 PM
    This person did gesture with their hands that the target was big. So maybe the weight is right just the target was more spread out making it bigger. Easier to detect deeper?
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