Two questions regarding the Goldquest.

[Anonymous]

How does the Goldquest compare to the SD's re. depth & ground handling? Also, what's the smallest size nugget it could find? Like Steve wrote on the Alaska mining forum; if a machine can do 90% of what an SD could at 30% of the price, it would really sell (not a direct quote).

 

[Anonymous]

Will.
The Goldscan was never built to compete with the "SD

 

[Anonymous]

Aside from that, how small of a target can it sense? When you said that it was equivalent to VLF machines did that include the ability to, let's, detect a grain sized nugget... Will.

 

[Anonymous]

Hi Will,
My testing was done with a pseudo Goldquest, meaning it is a modified unit similar to the Goldquest, but not quite. Mine has a home made coil, and isn't the quality of Eric's. Also, the Goldquest has a shorter delay so it should be a little more sensitive to smaller gold than mine. I do have a couple of small changes on mine that are not on the Goldquest. So, there are some basic differences, but not too much.
I can detect a nugget down to the 3 to 5 grain range. I haven't tried a grain or a 2 grain nugget so I cannot comment. Personally, if I were to be going after that size, I would use a VLF anyway.
Now, the Goldquest does not have ground cancelling, so some "bad" ground conditions can be a problem. The autotune helps significantly in this respect but it doesn't cancel the ground problems, just reduce them significantly.
In Gold Basin, I really didn't have any real ground problems as long as I search slowly, which is the way you are supposed to search anyway.
My testing indicated that the Goldquest holds its own against most PI's. Under controlled conditions, I found this little PI was quite competitive. No, it doesn't match the more expensive PIs under certain conditions, but was close.
In some places, the Goldquest might work better unless the Minelab was equipped with a special coil, since my experience so far has been the Goldquest is less sensitive to external noises, so there can be less chatter to mask a nugget.
As a PI, it is basically quiet over magnetite hotrocks, and different concentrations of black sand. There were a few places that would give me some response when I would hit pockets and then totally different soil. Those occurred when the coil was very close to the ground.
Red "hot" clay environments were a little harder, and I would have to raise the coil a little to minimize the problem.
If you are accustomed to ground cancelling on a PI, you will probably be disappointed, at least in some search areas. In others, you will be pleased. I found places on top of Rich Hill AZ where the machine was extremely quiet and ground cancelling wasn't necesary. Yet a couple of hundred yards away, I had to raise the coil a little and be more careful about coil heighth because the red hot ground.
This detector isn't an SD killer. It doesn't cost nearly as much so it isn't a pocket book killer either. For me, it is poor man's nugget hunting PI that is quite capable of finding gold.

 

[Anonymous]

[No message]

 

[Anonymous]

For the US, the government (FCC) regulates RF power emitted. Detectors aren't transmitting RF (hopefully not too much anyway).
Charles

 

[Anonymous]

Hey Will,
I have a Surfmaster PI and took it prospecting
back home in Northern California. It was pretty
stable but I missed my Goldmaster 3 VLF machine
when it came to digging up iron trash. I also
missed having an elliptical coil that was much
easier to squeeze into the tight places I needed
to get into. I would love to have a mid-priced
PI machine for gold prospecting that had any of
the two above-mentioned options. Until then, I
will probably stick to my VLF for prospecting.
Bobbus

 

[Anonymous]

Hi Bobbus,
Unfortunately, to the best of my knowledge, the Goldquest doesn't have a readily available elliptical coil.
However, another friend of mine has produced elliptical coil housings that work quite well, for those who are interested in building their own coil for their PI. The present size is about 9" by 13", but I think he is going to make a large one also. I will post more later about them once I check with him.
Fortunately, it is not nearly as difficult to build a coil for a PI as it is for a VLF type detector. Therefore, a person can personalize their detector much easier with a PI.
As for iron disc, I haven't tried the White's that much, but I haven't found an iron disc that is truly reliable.
As I mentioned below in a previous post, the use of the frequency control on a PI is not completely reliable as a disc mode either, but it is much better than nothing. A PB or a toggle switch can be used to quickly change the delay.
So, you can have a PI with a quick form of disc and an elliptical coil, but it does require some changes from the factory designed machine.
Right now, I have mine set up with a PB for a quick check of the object's composition, and an elliptical coil.
If I am planning on looking for really small nuggets, I will use the VLF, otherwise I will use the PI.
Reg

 

[Anonymous]

Hey Reg,
Thank you for the good insights. A 9x13 coil is
still pretty large to use prospecting. The Whites
GMs use a standard 10x5 coil and everyone wants
them to make even a smaller one like all the other
competitors. Do you know of anyone who could make
a custom 10x5 elliptical coil for a minimal price?
I have a Surfmaster PI that I am sending out to Mr.Bill for a more "gold-sensitive" upgrade and
I would like to have an elliptical coil on my PI
machine just to try out in the hills. Let me know
if you have anyone in mind. Thanks! Bobbus

 

[Anonymous]

Hi Bobbus,
Sorry, I don't know anybody making that size coil housing or who would make a custom coil for you with that size housing.
I elected to not go to a narrower coil. I did some experimenting with one about the size you mentioned and didn't like the results. I probably should experiment again, since I have changed the detector quite a bit since I tried a coil that was quite narrow.
Even with the narrower coil, I wouldn't expect to see much improvement on smaller nuggets like you can get on a VLF. I did see a depth loss though on my previous tests.
With the open center coil I have, I can slide over many of the rocks rather than try to get in between them. This allows me to get closer to the ground in many cases. Also, the tips of the coil are very sensitive so I can probe the tip into the area also where the rock is too big to fit in the opening.
My next coil is going to be a much bigger one.
Reg

 

[Anonymous]

Reg,
Surely a 10x5 elliptical coil would be more sensitive at its tip and be more sensitive on the smaller nuggets than your open centre coil, as the elliptical shape would have a tighter field.
Also if your open centre coil is round it could not probe in areas the ellipticals tip could fit.
Regards Gary.

 

[Anonymous]

Hi Gary,
The home made coil I use is an elliptical coil, a 9" by 13".
It was built for nugget hunting to get into tighter places than I can with the 11" round coil.
Some time back, I experimented with different elliptical shapes before this size coil was built. What I found was I really didn't see much of a change in signal strength from a smaller nugget when the coil was narrower.
I am sure there would be a slight increase, due to the reasons you mentioned, but it wasn't nearly as obvious as the overall depth loss I noticed from a narrower design on other size objects.
The nice thing about a PI is you can readily change the coil shape and size and experiment. Which is what I did.
I found the delay to be much more critical than the size of the coil when trying to find small nuggets.
Several days back, I took one of my coils and made a figure 8 coil, which basically made the size of each coil less than 1/2 the diameter of the original design.
I really didn't observe any significant increase in signal strength to my small test nuggets, but that was just listening to the target and not actually measuring the signal. What I did notice was the overall depth loss to larger nuggets.
Like I said before, I do need to experiment more with smaller nuggets to see if there is any significant signal increases with a more narrow coil to really small nuggets.
Reg

 

[Anonymous]

Hi Again,
I did a quick experiment with my modified Goldscan which now has a delay of about 13 usec.
I tested a 1 1/2 grain nugget and got no response from it using the 11" coil. I then switched to the built in probe which is about 1" in diameter and tried to detect the small nugget again. Notthing, zilch.
I then did a quick distance test comparing a couple of other small nuggets. Both the large coil and the probe would pick them up at about the same distance.
I do recall that when I was initially trying to reduce the delay that the narrow ends of my elliptical coil were a little more sensitive to my small test nuggets, but only for a certain size nugget. Any larger size nugget and the whole coil would detect them at about the same distance. Any smaller of a nugget and I just wouldn't get enough of a response anywhere on the coil that I could say was a real target response.
I guess what I am trying to say is I feel a PI is distinctly different than a VLF in its response to small nuggets. The principals of detection are distinctively different between the two types of detectors.
On a PI, it is my opinion the delay is more critical than coil size. Yes, a narrower coil does enhance a certain size nugget's response a little more, but I feel a smaller coil will really will not pick up or sense smaller nuggets than the delay will allow.
I do fully agree that a smaller narrow coil will work better in certain areas simply because you can get it into tighter places. In many instances you can get the coil closer to the ground, or better stated, closer to the nugget.
Reg

 

[Anonymous]

Reg: Hey, you said Goldscan. Did you mean Goldquest? Thanks, BJR

 

[Anonymous]

Hi BJR,
I meant Goldscan. I used one of Eric's older Goldscans, I also own, for the test rather than my modified Beachscan.
I used the Goldscan because it does have a probe built in, and I don't have any small coils built up at the present time for any of my PI detectors. The Goldscan is presently set up with about the same delay as my modified Beachscan.
I figured the probe should show any significant improvement in response to real small nuggets if there was going to be any because of coil size.
Sorry, I should have been more specific as to the version of detector I used and why.
Reg

 

[Anonymous]

G'Day Reg,
Sorry I misread you test coil shape.
I was going to post a question regarding "Coil size vs Pulse delay or Pulse width" on small nuggets?
You said in your reply that "delay is more critical than coil size"
I have a SD2000 without the modification that gives a shorter Tx pulse - shorter pulse delay and shorter off time - thus, faster reponse on ground.
So I thought by useing a smaller coil I could improve sesitivity on tiny nuggets without the mod. However from your reply coil size does not give this sensitivity enough on PI's.
It would seem though that coil size on a VLF works better on tiny nuggets.
Gary.

 

[Anonymous]

Hi Gary,
First, a smaller coil does work better on a VLF, but that is because of several factors including the concentration of the field in a smaller area. Thus, there should be a greater signal return from a small nugget using a small coil when compared to a larger coil, providing the coils are fundamentally the same.
Simply stated, VLF's work quite differently than a PI from many standpoints.
On a PI, the smaller coil should also concentrate the transmitted signal and thus the smaller nugget should give a stonger response also.
However, the size of nugget that can be detected is also directly related to the time constant of that nugget. The smaller the nugget, the shorter the time constant. The shorter the time constant, the faster the signal will decay.
If the signal from a small nugget decays before the sample is taken, you will not hear any response. That is why a shorter delay is necessary. You may have a stronger initial signal using a smaller coil, but that initially stronger signal may still disappear before the sample is taken.
I have experimented with cranking the sensitivity up also to try to detect smaller nuggets and it just doesn't work effectively. Basically, reducing the coil size is increasing the sensitivity by producing a stronger initial signal.
I have seen by experimentation one can increase the sensitivity and reduce coil size, and you will see some improvement in the detection of smaller nuggets, but it is very limited, and still dependent upon the nugget size. However, I have seen a much greater improvement in signal response from a smaller nugget just by shortening the delay a few microseconds.
The next item that significantly reduces the ability to detect both smaller nuggets and the depth capabilities is simply the noise factor. Any reduction in noise from things like the preamp or the coil make a big difference.
I am sure there are more and better answers than I can provide, but what I have just mentioned is what I have experienced from experimenting. If there is anybody out there who has experienced something different I hope they jump in and tell me my weaknesses and the flaws in my thinking. I am old, but still willing to learn.
I hope what I have posted helps.
Reg

 

[Anonymous]

Hi Reg and all,
I have been away in Ireland for a few days, otherwise I would have joined in sooner.
Yes, I agree that the pulse delay is the determining factor in small non-ferrous object sensitivity, with any given coil size. A small coil, and especially a ferrite cored probe, has a much higher flux density, but once the signal has decayed to zero, no amount of cranking up the flux will make it detectable. Provided an object is detectable, then there will be a benefit in a higher flux concentration.
Having said this, it is easier with a small coil to run at an even shorter pulse delay, because of its lower self capacitance and also the reduction in inductance for a given number of turns.
Eric.