A
Anonymous
Guest
Hi All,
First I would like to say I don't really have a Goldquest but do have a modified Beachscan set to the same delay as the GQ and equipped with the new autotune feature so the results should be about the same. I guess I should say my Beachscan is more like a GQ clone.
Anyway, I built and installed a DD coil on my GQ clone and it worked fantastic. A couple of things came out of the experiment that I thought people should know.
First, the DD does an excellent job of eliminating the ground signal if the coil is properly built. My experimenting at home and use at Gold Basin indicated the ground signal can be minimized to the point that it is almost non-existent over a wide range of conditions. As such, just a DD coil may be better than ground balance (GB) in many places simply because GB has a tendency to introduce noise while the DD seems to actually reduce noise when compared to a mono with no GB.
I am sure there will be places where just the DD will not completely eliminate the ground response, but where I live and at Gold Basin, it sure did a fantastic job.
I found the DD to give a slightly weaker signal to really small gold, but because of the fact there is less noise and the target response is more distinct, I can actually detect smaller nuggets better and deeper. I could tell the signal level difference because I have built a VCO type audio so any target will both change in volume and frequency. There was a slightly less tone change on the DD to my small test nuggets, yet I could hear them farther from the coil. I attributed this to the reduction in noise level.
What really surprised me was the fact that my 11" DD would detect a nickel at a greater range than my home made 9" by 13" mono. I gained an inch or so. How does between 16" and 17" air test sound? It sure looked and sounded good to me. (I have just built an 8" by 11" DD which did drop me back down to between 13" and 14" on a nickel.)
My limited testing of in ground targets indicate I get about the same depth as the air testing which also impressed me. This was done in extremely mineralized ground, but was not a red clay environment. So far, I have not had a chance to test in under red clay conditions but hope to do so in the near future.
Now for the down sides and there are a few. The DD does not do quite as well on small meteorites like those found in Gold Basin as the mono coil does. I suspect this is because the meteorite signal is more like a ground change than a metal target. It does extremely well on medium and larger meteorites. That is what I found this last trip was one nice meteorite, plus the usual quantity of trash.
One thing I also noticed with the DD coil is the use of the delay to test for iron is not as accurate. For some reason, at least on my detector, I don't get the usual easy separation of targets by turning the delay up. I am not sure why this is the case and I am looking into it.
Now, the big down side. This is a do it yourself project since there are no readily available coils. The detector does require some minor modifications which really should only be done by someone who has worked on pc boards. One should also realize this mod is not sanctioned or approved by Eric or Mr. Bill so it will most likely void the warranty. More important, any problems one might encounter shouldn't be directed them since both are too busy with other projects to try to coach someone though possible mistakes.
Setting up a DD coil isn't really difficult but the best results can only be done with a scope. Of course, proper shielding is required for best results also.
So, if you are a "do it yourselfer" like me and you like to experiment, then this is a great project to improve a really good detector, especially for nugget hunting.
Finally, how does the GQ equipped with a DD coil stack up against the big boys on the block. Well, it isn't a giant killer, but it can easily bruise their ego, especially on small nugget response.
Reg
First I would like to say I don't really have a Goldquest but do have a modified Beachscan set to the same delay as the GQ and equipped with the new autotune feature so the results should be about the same. I guess I should say my Beachscan is more like a GQ clone.
Anyway, I built and installed a DD coil on my GQ clone and it worked fantastic. A couple of things came out of the experiment that I thought people should know.
First, the DD does an excellent job of eliminating the ground signal if the coil is properly built. My experimenting at home and use at Gold Basin indicated the ground signal can be minimized to the point that it is almost non-existent over a wide range of conditions. As such, just a DD coil may be better than ground balance (GB) in many places simply because GB has a tendency to introduce noise while the DD seems to actually reduce noise when compared to a mono with no GB.
I am sure there will be places where just the DD will not completely eliminate the ground response, but where I live and at Gold Basin, it sure did a fantastic job.
I found the DD to give a slightly weaker signal to really small gold, but because of the fact there is less noise and the target response is more distinct, I can actually detect smaller nuggets better and deeper. I could tell the signal level difference because I have built a VCO type audio so any target will both change in volume and frequency. There was a slightly less tone change on the DD to my small test nuggets, yet I could hear them farther from the coil. I attributed this to the reduction in noise level.
What really surprised me was the fact that my 11" DD would detect a nickel at a greater range than my home made 9" by 13" mono. I gained an inch or so. How does between 16" and 17" air test sound? It sure looked and sounded good to me. (I have just built an 8" by 11" DD which did drop me back down to between 13" and 14" on a nickel.)
My limited testing of in ground targets indicate I get about the same depth as the air testing which also impressed me. This was done in extremely mineralized ground, but was not a red clay environment. So far, I have not had a chance to test in under red clay conditions but hope to do so in the near future.
Now for the down sides and there are a few. The DD does not do quite as well on small meteorites like those found in Gold Basin as the mono coil does. I suspect this is because the meteorite signal is more like a ground change than a metal target. It does extremely well on medium and larger meteorites. That is what I found this last trip was one nice meteorite, plus the usual quantity of trash.
One thing I also noticed with the DD coil is the use of the delay to test for iron is not as accurate. For some reason, at least on my detector, I don't get the usual easy separation of targets by turning the delay up. I am not sure why this is the case and I am looking into it.
Now, the big down side. This is a do it yourself project since there are no readily available coils. The detector does require some minor modifications which really should only be done by someone who has worked on pc boards. One should also realize this mod is not sanctioned or approved by Eric or Mr. Bill so it will most likely void the warranty. More important, any problems one might encounter shouldn't be directed them since both are too busy with other projects to try to coach someone though possible mistakes.
Setting up a DD coil isn't really difficult but the best results can only be done with a scope. Of course, proper shielding is required for best results also.
So, if you are a "do it yourselfer" like me and you like to experiment, then this is a great project to improve a really good detector, especially for nugget hunting.
Finally, how does the GQ equipped with a DD coil stack up against the big boys on the block. Well, it isn't a giant killer, but it can easily bruise their ego, especially on small nugget response.
Reg
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