INFO. ON G.B., SENS. and THRES., WITH GAMMA 6000

ToddB64

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Georgetown, Ohio, USA
Hi All ! :tiphat:

Using the Teknetics Gamma 6000 digital metal detector as the subject in this post, it seems to me that one should always start the machine setup by First Ground Balancing using the instructions provided in the Gamma manual, in order to get rid of ground mineral affects before activating any other machine settings.

Second, increase the Sensitivity setting as high as possible until you hear EMI (Electromagnetic Interference), and then reduce Sens. until no more EMI is heard. Eliminating EMI will allow you to more clearly hear and analyze the audio signal characteristics of trash and/or good targets.

Third, Threshold. After reading and digesting the information in References #1 and #2 below and also reading the following paragraph concerning gain and threshold settings, decide if you want to add gain alone, or gain and some threshold adjustment as depicted by the graph in REFERENCE #2 . Lowering the Threshold by increasing Sensitivity between 90 and 94 exposes more targets according to BottleCapKing's underlined sentence in REFERENCE #1, second paragraph.

With further reference to Sensitivity, the Gamma manual states "From 05 to 90 gain is changing. Above 90, the threshold level changes. Setting above 94 will be noisy or sound erratic.".

This post comprises my suggestions for the initial Gamma 6000 machine setup and I believe those to be logical and in proper sequence. The balance of setups and the sequence of activating those are left to your preference.

Hope this is helpful !

ToddB64
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REFERENCE #1: http://metaldetectingforum.com/showthread.php?t=83973&page=3

Friendly Metal Detector Forums > Detectors and Gear > All About Detectors > by Dsparil, Titled Gain > Thread Page #3.

BottleCapKing Post #21 10-28-16, 01:43 PM
Elite Member

Even with Metal Detectors, gain and sensitivity are not the same thing.

Gain amplifies the signal coming out of the coil before being processed. Sensitivity adjusts the threshold at which the processors consider anything above to be a signal. When you increase sensitivity, you are lowering that threshold. When you decrease sensitivity, you are raising the threshold.

Gain has the problem of also amplifying ground noise. If gain is set too high, you are going to get a lot of noise. Sensitivity, if set too high will make bad targets and ground noise appear to be good targets. So, they both perform specific functions and have distinct consequences if set too high or too low.
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REFERENCE #2 : http://www.fisherlab.com/hobby/dave-johnson-essays.htm
Fisher Gold & Treasure Detectors | Dave Johnson's Essays
Dave Johnson, Chief Designer, FTP & Fisher
Essay Title:
Discrimination mode “Sensitivity” and “Depth” in single-frequency VLF metal detectors
“Sensitivity control” A control labeled “sensitivity”. It actually controls either gain or threshold, or a combination of both, depending on the machine. If both, the higher settings vary threshold and the lower settings vary gain.

ToddB64 Personal Comment: I extracted the above paragraph from Dave Johnson's essays and pasted it here for your reference. I also copied and pasted the graph below from a Digger27 post, to help you visualize what Dave is saying.
 

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nice post, what else have you found on your gamma?
 
The Gamma is a great buy right now $239. Google tekneticsdirect to see where.
 
nice post, what else have you found on your gamma?

Hi juit :tiphat:

To tell the truth, I haven't been using the Gamma, in favor of my Compadre. I go in spurts, using one particular detector for several weeks or even months and then switching to another. As you see from my signature, I now have 5 to choose from.

Years ago Tabdog got me all excited here on FMDF with his posts and photos of coins and jewelry using his two Compadres, called his "Speedys" as I recall. Unfortunately, he contracted a virus infection called MRSA and wasn't able to continue metal detecting I guess, as he hasn't been posting here for a very long time.

So, I just had to have a new "C" and purchased one with the 5.75 " coil, which was standard at the time.

I believe it was Monte V. Berry who taught me how to move the Compadre's coil around the big iron supporting Tot Lot equipment at public parks. The usual problem that kept detectorists away from the big iron was the loud response signal whenever the coil came near the supports, which caused the operator to move away and go elsewhere. So coins and jewelry that were under the wood chips piled up against these supports were left and never found. That is, until we learned to move the coil slowly around the big iron, keeping the toe of the coil pointed toward the support and listening for a "double" beep, one for the big iron and another for any coin or jewelry item that happened to be there. It wasn't long until others learned this technique and the "cat was out of the bag". Eventually Monte started his own metal detecting website called the American Heritage Research and Preservation Society (AHRPS).

Then I started reading Digger27's threads and posts here on FMDF. BTW, this "Friendly"site was the very first metal detecting website I had ever joined and the Garrett Ace 250 was "the best bang for your buck" at the time, so I bought one and that was my first detector too, by golly !
Some of Digger27's best threads and posts are in the "Church of the Compadre" thread. He bought his first Compadre as a previously-owned unit from Skiwhiz who had previously tweaked the sensitivity tuner inside the control box up a bit and this unit was wearing a 7" coil when he bought it and I believe it still is. I see you made some smart choices on your metal detectors; the 7"coil Compadre and the Gamma.....great start juit !

Digger27 put in his time, hundreds and hundreds of hours (He might say thousands) learning the strong points of the "C" and honing his skills and methods to perfection. He really has a heart for helping others learn his methods to increase their abilities with the "C" and other machines.

If you would like to read some of Digger27's threads and posts, I am pleased to give you some URL addresses below, beginning with the following:

http://metaldetectingforum.com/showthread.php?t=84048

Use the same basic address http://metaldetectingforum.com/showthread.php?t= and just add the numbers below after the = sign to read these 5 additional threads.

78080
86773
97471
98640
201661

In case you don't know, these addresses appear at the top of the FMDF website pages. If you come across any other threads that you would like to visit again, just copy the address and save it. Then later you can copy & paste (or type) it into your browser or search engine window and it will take you right to the FMDF website and thread...a lot faster ! Remember though, some of the addresses for other pages can be different than the above.

Hope this reply hasn't put you to sleep. :putertired:

ToddB64
 
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I want the compadre for play tots and small areas to search, the gamma with 11 coil for beach and bike trails, planin to get a black box white in the future
 
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