Sensitivity or Gain on your detector
Last Post 05 Apr 2017 07:47 PM by Terrance Cieszki. 10 Replies.
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WILLIAM SOUTHERNUser is Offline
Sluicer
Sluicer
Posts:54



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13 Dec 2016 04:31 PM

     

    Hi All, Nugget Shooter's tip for today involves setting up your detector's Gain or Sensitivity.... First to those familiar with CB Radios TX Gain is more power out and RX Gain is receive, so this said all metal detectors currently used for the most part are VLF or PI and even ZVT, but all are ruled by their RF function in that if not set properly you will miss targets. So how do you set it up?

     

     

    Quick and simple with PI air tune to eliminate EMI and ground balance in factory preset, VLF get ground balanced in factory preset, set threshold as well. then holding your coil a couple inches off the ground and turn your Gain/Sensitivity all the way down. Then up one setting at a time until it begins to act unstable, back a click and hunt.

     

     

    So if you are a feller hunting in high unstable gain you may be finding allot of targets shallow, but wonder where the deep ones others speak of are? You are walking over them because your detector is not stable enough to hear the slight break in threshold....

     

     

    Good Hunting.... Bill

    ADAM ANDREWSUser is Offline
    Treasure Hunter
    Treasure Hunter
    Posts:253



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    13 Dec 2016 09:52 PM

      I'm pretty sure it's all about the ground balance, and the $700 detectors pass up nuggets that the Minelab 2300 can find no problem. My mining friends like to bury flakes taped to a card to get the sensitivity right at its lowest level

    WILLIAM SOUTHERNUser is Offline
    Sluicer
    Sluicer
    Posts:54



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    14 Dec 2016 06:39 AM
    Ground balance is indeed important but if sensitivity is not correct a stable ground balance will not be possible in most cases. The threshold which is the voice of the detector must be set at a level where it is stable and just audible as well. Then sensitivity is set properly once again after threshold and ground balance, these 3 settings must be mastered to be successful and though I am a Minelab user (2300 and 7000) I have no problem taking a 700.00 Gold Bug 2 or other brands into areas where the higher end detectors have been and find gold they missed. Thing is even when settings are correct some folks hunt way to fast and miss targets as well. Nugget Shooting is a skill that needs to be learned by trial and error and education, but once mastered a detector is a wonderful tool 700.00 or 8000.00. The real key is knowing how to do the research to get into spots others do not go and this I teach at my seminars during the Gold Shows and at club meetings. After almost 30 years of almost exclusively metal detecting I now enjoy helping others almost more than finding gold myself. Each year I get folks calling or emailing me thanking me for opening their eyes as to how to properly set up their detectors because they found that first nugget. Many consider the detectors that have many settings and options too hard to use and opt for a "turn on and go" model or hunt in factory presets only. Why? All those extra settings and adjustment options allow the user to adapt to any soil and or conditions and is why some detectors are way more costly, options. Why buy a high end piece of equipment and not take the time to fully learn and understand it? Metal detecting is likely the hardest method of gold prospecting to learn, but also can be the most rewarding.

    Sensitivity is not set to a target as a rule because what you are doing in adjusting it is making the detector able to hear at a very stable level without  falsing or hearing excess EMI and this adjustment is made without being over a metal target for best results. Each area will indeed require different settings, but the most important will still be the "gain" or "sensitivity" (depending on manufacturer) after air tuning and ground balance try turning your gain all the way down, then slowly up until you start hearing the threshold get unstable, back one number and hunt. All coils will allow for a different setting due to size or shape and remember running a high gain making the detector unstable will indeed hit hard on small stuff on the surface, but you will miss deep targets simply because you can not hear them. Higher gain does not put out any more power, it is not TX (transmit) it is RX (receive) and having it set for the most stable reception means more finds.... 

    LEO LORENZUser is Offline
    Lost Dutchman
    Lost Dutchman
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    14 Dec 2016 07:55 AM
    Thanks Bill.......what you just said...." Higher gain does not put out any more power, it is not TX (transmit) it is RX (receive)" just made me realize a very basic concept which I was always overlooking or not really considering. And that may be why I am not finding much even though I am in the right locations for gold. For some stupid reason....I have always been thinking of trying to turn the gain up as much as possible and then Ground Balancing turned out to be a very unstable situation. I was always thinking that I would lose depth. Metal detectors are no different than radio's or radar, which I should have known better being in aviation electronics for 30 years. The transmitter is usually always a "fixed" amount of power which is transmitted through the antenna, measured in watts. When receiving back a signal through the antenna or "coil" when detecting... the sensitivity of the device is very important. The sensitivity adjustment prevents the machine from picking up too much reflected ground noise or as in radar....clutter on the display. The amount of power being transmitted to the ground from our detectors is fixed - no more or less than what the manufacturer designed it to be, unless your batteries get weak and cannot allow the transmitter to produce the full power. But what we are more interested in is the ability to hear the received signal back through the coil. The sensitivity adjustment will fine tune that "clutter noise" which causes us to not hear the subtle changes in the threshold for a deeper target. I dont know why I never applied this logic to my detecting with the Gold Bug Pro, which now that you mentioned now made me realize how to change my methods.
    Leo
    WILLIAM SOUTHERNUser is Offline
    Sluicer
    Sluicer
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    14 Dec 2016 08:02 AM

     

    Leo that was a great post and thanks for sharing your knowledge on radar and such, you have given me another teaching tool as I have always used the gain on a CB Radio as my comparison, but some younger folks do not know about them  And by the way you nailed it and I am guessing perhaps a few more deeper targets and gold in your future.

    Travis NixUser is Offline
    Dredger
    Dredger
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    21 Dec 2016 03:38 PM
    it makes a lot more sense to me being put into that perspective..
    and I can agree I need to slow down... way down.. I have always been eager to hear that beep, and come to find out its just trash.. thanks guys
    Terrance CieszkiUser is Offline
    Greenhorn
    Greenhorn
    Posts:20



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    23 Mar 2017 05:47 PM
    Are you Wm Southern, as in Bob Southern and Rob Allison - Minelab experts? GLAD to meet you! I am TerryC (Treasurenet site). I just saw one of your videos posted by Terry Soloman yesterday. GREAT job guys!  TTC
    Come out from under your bed today, DO SOMETHING!
    Terrance CieszkiUser is Offline
    Greenhorn
    Greenhorn
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    23 Mar 2017 06:06 PM
    Adam, try this. Go to Staples or similar and pick up some "hot" laminating sheets. Cut them length wise so you have an 11 inch long piece that is about 2 inches wide. At one end, put your target... gold flakes, slivers of copper penny, slivers of silver, etc. At the other end, put a label inside the sheet(s). Using an iron (does anyone still use them? I have the laminator) "hot laminate" the sheets. You now have a set of waterproof test targets that can be easily buried at precise depths up to 11 inches and can be easily pulled out of the soil without re-digging.  TTC
    Come out from under your bed today, DO SOMETHING!
    Bob ClarkUser is Offline
    Greenhorn
    Greenhorn
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    05 Apr 2017 04:08 PM
    Thanks bill, and good idea Terrance
    Larry SugdenUser is Offline
    Greenhorn
    Greenhorn
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    05 Apr 2017 04:59 PM
    Good idea, Terrance. I use coin envelopes that you use for displaying coins. They are cheap and available any place that sells coin collecting supplies. They work great, just tape them instead of stapling. Do check them often to make sure the cellophane center doesn't tear and you lose your training target.



    I would also recommend finding a copy of the book, "Gold Prospecting With a VLF Metal Detector" by Dave Johnson. The book is available as a free download (I just can't remember where). He explains some deep technical details, as well as some "Beginner's Guide" type info. I learned so much from it.
    Terrance CieszkiUser is Offline
    Greenhorn
    Greenhorn
    Posts:20



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    05 Apr 2017 07:47 PM
    Larry, try Jim Straight's "The Nuggetshooter's Bible." Seventh edition. A very good read. A little dated (2004) but very informative.  TTC
    Come out from under your bed today, DO SOMETHING!
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