I just received a 5" coil for my Gamma. When I try to Ground Grab, while pumping the coil I get that "pinball machine gone wild" sound and the display does not lock into a GB number as with my 11" coil, it just keeps making the noise and numbers flick by. I've tried it on a number of ground types with the same result. When I release the Pinpoint button the number it shows does consistently, repeatedly come up for the same piece of ground though. For example, 64 repeatedly on a patch of lawn and 70 repeatedly on a patch of bark chirp. Is this what I should expect? Is there something wrong with the coil? Could it be a T2 coil that is not labeled right? Thanks.
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Gamma with 5" coil - Ground Grab Working Right?
- Thread starter StvS
- Start date
BuckeyeBrad
New member
Did you by chance get this Gamma used and if so, is it an earlier build unit? Some of the early ones did what you're referring to in that it was fairly common to get that "space invader" audio when fast grabbing. Technically, that audio is a prompt that the detector "can't" balance because you're over a metal object, or the ground is too hot, etc. You might want to try and balance using a lower sensitivity setting and then turn it up to the setting where you want to hunt. The good news is they typically were doing the job of balancing properly and from what you say, your Gamma is doing the same. If memory serves me correctly, there was a subsequent software update that alleviated this "issue". Bottom line is you're probably fine as long as you know the detector is arriving at different GB points at different sites so there shouldn't be anything to worry about.
BuckeyeBrad
New member
As you probably already know, (but just in case you don't) after you perform a fast grab (FG) over metal free ground, go to all metal and dial in a bit of threshold with the sensitivity setting and then double check how accurate the FG setting is by bobbing the coil over the same metal free ground. If the unit is working correctly, your FG point should be virtually the same as if you set the GB manually or at least within a couple 1/10/s of a whole number. If that happens, all is well.
TerraDigger
New member
This is from the Fisher F5 guru, Mike Hillis. It applies to your unit, along with several other Tek/Fisher units:
This is how I am achieving stable setups: (Mike Hillis)
With the coil held flat and unmoving on the ground, I select the tone id/target processing mode, then turn the sensitivity and discrimination settings both to zero.
Begin raising the sensitivity setting until you start to just hear noise. I find that in my areas that it doesn't take much, usually somewhere around a sens setting of 15-25 before I start picking up electrical interference noise. Then adjust the sensitivity setting down a number or two so that the noise is barely coming through and at this point run through the frequency selections to find the one that works best. I have found that doing the freq check at this level ensures that I am choosing the best one because I'm not overpowering the circuit, which in turn, lets me really hear which one works the best. If you can't tell a sound difference as you cycle through the frequencies, then your sensitivity level it too high and you need to back it down another number.
Once you've selected the quietest frequency, then raise the discrimination setting to 10 (full iron acceptance or zero discrimination). Now raise the sensitivity settings until you hear noise again and then back off a number or two until its quiet. Have now set the machine stable as far as electrical interference is concerned.
This easily lets me raise the sensitivity up into the high 70s, low 80's with no noise from electrical interference. Now, if the ground will let me, I can raise my disc up to around 25 and increase my sensitivity into the 90s and still remain stable. Thats IF the ground will let me.
(Terra's note): After above setup procedure is completed, then do a manual ground balance
Make the disc adjustments according to where you want your disc level to be on your particular machine.........Terra
This is how I am achieving stable setups: (Mike Hillis)
With the coil held flat and unmoving on the ground, I select the tone id/target processing mode, then turn the sensitivity and discrimination settings both to zero.
Begin raising the sensitivity setting until you start to just hear noise. I find that in my areas that it doesn't take much, usually somewhere around a sens setting of 15-25 before I start picking up electrical interference noise. Then adjust the sensitivity setting down a number or two so that the noise is barely coming through and at this point run through the frequency selections to find the one that works best. I have found that doing the freq check at this level ensures that I am choosing the best one because I'm not overpowering the circuit, which in turn, lets me really hear which one works the best. If you can't tell a sound difference as you cycle through the frequencies, then your sensitivity level it too high and you need to back it down another number.
Once you've selected the quietest frequency, then raise the discrimination setting to 10 (full iron acceptance or zero discrimination). Now raise the sensitivity settings until you hear noise again and then back off a number or two until its quiet. Have now set the machine stable as far as electrical interference is concerned.
This easily lets me raise the sensitivity up into the high 70s, low 80's with no noise from electrical interference. Now, if the ground will let me, I can raise my disc up to around 25 and increase my sensitivity into the 90s and still remain stable. Thats IF the ground will let me.
(Terra's note): After above setup procedure is completed, then do a manual ground balance
Make the disc adjustments according to where you want your disc level to be on your particular machine.........Terra
Thanks! I know I can shift frequencies on my T2, but I'll have to see if I have that feature on the Gamma; if not, I'll forgo the frequency shifting part. Did I understand correctly that the second time you raise the sensitivity, after you've set Discrim at 10, you typically get it into the 70's and 80's?
jimmy clark
Active member
i just bought a new gamma, an it does the space ship sound when i go to ground grab even if the coil is in the air. does this mean i got an old stile detector ?
TerraDigger
New member
Yes, to your question. But it depends on the soil mineralization. Your soil may differ and sensitivity setting may vary. Mike Hillis lives in New Mexico. Fairly high mineralization, as all western states are. It's the technique that is important, not Mike's individual detector settings.
There is two different suggestions for coil height in the Owner's Manual, and I always suggest the second one. On Pg. 17, under 'Automatic Ground Balancing Procedure Using Ground Grab' it states (in #2) to hold the search coil about one foot above the ground. Then it states to push-and-hold the Ground Grab buttons and pump the search coil up-and-down over the ground. To do it (briskly) ones or twice a second, lifting the coil to 6" and then lowering it to about 1".
On Pg. 18, it repeats briskly pumping the search coil from about 6" to 1" and back up to 6" when using the Ground Grab function. I have found it better to start with the coil held near the ground in many places because starting in the air, especially if the coil is 1 foot or higher, pressing the Ground Grab button will likely cause the unable to balance audio alert. Remember, the detector doesn't Ground balance on soils that have a reading LOWER than '40' using Ground Grab, and if you start it with the coil too far off the ground, you can get that audio.
Also, when using the small 5" DD coil I find it even more important to stick with the 6" coil height at the top of the pumping action to eliminate the alert audio.
While much of the dirt and grassy sites in our area of NW Oregon and SW Washington are generally more mineralized (iron), we do have some mellower areas, such as some ground close to the wood-chip playgrounds with a blend of chips and dirt or sand from prior use. Also, trying to GB over the wood-chips alone can be difficult because they might be in too thick of a layer and there's no close ground below them to properly balance to.
I occasionally have a little challenge using the Ground Grab with my Gamma, and have with the Omega, but when I do I just continue with a quick-brisk bobbing of the search coil and manually adjust it. It's quick and simple. I never bother with reducing the Sensitivity or other adjustments before I do the Ground Balance as there really isn't a real need to.
Monte
On Pg. 18, it repeats briskly pumping the search coil from about 6" to 1" and back up to 6" when using the Ground Grab function. I have found it better to start with the coil held near the ground in many places because starting in the air, especially if the coil is 1 foot or higher, pressing the Ground Grab button will likely cause the unable to balance audio alert. Remember, the detector doesn't Ground balance on soils that have a reading LOWER than '40' using Ground Grab, and if you start it with the coil too far off the ground, you can get that audio.
Also, when using the small 5" DD coil I find it even more important to stick with the 6" coil height at the top of the pumping action to eliminate the alert audio.
While much of the dirt and grassy sites in our area of NW Oregon and SW Washington are generally more mineralized (iron), we do have some mellower areas, such as some ground close to the wood-chip playgrounds with a blend of chips and dirt or sand from prior use. Also, trying to GB over the wood-chips alone can be difficult because they might be in too thick of a layer and there's no close ground below them to properly balance to.
I occasionally have a little challenge using the Ground Grab with my Gamma, and have with the Omega, but when I do I just continue with a quick-brisk bobbing of the search coil and manually adjust it. It's quick and simple. I never bother with reducing the Sensitivity or other adjustments before I do the Ground Balance as there really isn't a real need to.
Monte
Thanks! I think it is GB'ing accurately. When I Ground Grab, then pump the coil up and down and release the button, despite me getting the "space-invaders" warning, I get a GB number. When I GB manually from there it seems to be on the money or a click or two away, almost always on the same GB number though. It's just abit disconcerting that that happens with the 5" coil, but not the 8" coil. It's actually easier to GB the Gamma than the Eldorado, since the Gamma has 100 increments to the Eldorado's very touchy 3-3/4 turn pot.
Monte, I'll try your hint about starting close to the ground and pay attention to not raising the coil more than 6" (paritcularly with the 5" DD coil). I have had trouble Ground Grabbing on bark chip for sure.. Most of the GB numbers I'm seeing are 62-71 in the parks..
Monte, I'll try your hint about starting close to the ground and pay attention to not raising the coil more than 6" (paritcularly with the 5" DD coil). I have had trouble Ground Grabbing on bark chip for sure.. Most of the GB numbers I'm seeing are 62-71 in the parks..