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How Quiet is Goldscan 5?

Hi,

I've been using my ground balancing PI units to hunt coins. The main problem has been noise in urban areas. The Infinium was a good coin machine, but was very noisy in urban settings. Constant background bleeping. My GP 3500 is better but still gets quite a bit of interference, unless you go to cancel mode, and I worry about lost performance then. I see Coiltek has a new anti-interference coil out I may need to try.

Long story short, how quiet is the Goldscan in an urban setting compared to these other units? I really do not need another PI unit, but if the Goldscan is more than just a little bit quieter it would be a huge selling point for my purposes. I want to use it nugget hunting, of course, but am also very interested in using it as a freshwater wading unit in town.

Steve Herschbach
 

Mr.Bill

New member
Steve

The Goldscan 5 is very quiet in most any setting. I use mine in a very active commercial environment. I hunt public beach
 

Buz

New member
Eric's Goldquest is very nice and compatible machine I haven't had any problems with background noise even using the :coiltec: coil. I don't know about the Goldscan 5 ,who would know more about PI detectors than the inventor Eric Foster ,I think Mr Bill is right on :thumbup:

That my opinion:twodetecting:



Buzz
 

Reg

New member
Hi Steve,

I have no doubt the GS 5 will be quieter than your other PI's, but will still be noisier than most VLF's.

Now, that doesn't really answer your question exactly, but I can say that my limited testing let me check a buried 1 gram nugget within 50 feet from my computer.

When I had Jim French's GS 5 I did some comparisons of the GS to my PI's which are also Eric Foster machines. I do live almost dead center in a city of 100,000, have a Pizza Hut directly behind me, a Spa dealership within a block, a dental office within a block and a dental lab where they make false teeth in the same general area. Finally, there is a pottery house within a block where they kiln dry various pottery objects.

So, as you can see I can have a wide variety of sources of external noise. Now, on bad days, I will notice enough noise to lose two to 4 inches in overall depth. such noise will obviously be a somewhat noisy threshold. Strangely, it isn't as bad as one might think and not nearly as bad as a SD 2100 which really warbles bad in the same location.

On good days, even with the computer on, any of Eric's machines including the GS 5 are extremely quiet. So, general external noises can have an effect, but no where nearly as bad as found on some other machines.

From a technical standpoint there are two reasons for this noise reduction. One reason is the actual design of the unit itself. Eric has taken care to design a machine that tries to minimize much of this noise by using various types of filtering as well as summing. I know this because I am fortunate enough to have some of the technical information of just how they are built and I have built a form of ground balancing for my Goldquest clone.

The second reason is the coil design. In this area, Eric uses a technique of shielding that is designed to reduce the effects of external noise. I have adopted this basic technique and use it in my coils that I make. I find it significantly reduces the noise enough that I can do some reasonable testing inside.

Now, knowing this information about coil shielding, one should expect greater noise when using third party coils. Just how much additional noise is unknown because it can change from coil to coil. Also, coil size will have an effect. A larger coil will have greater noise. A mono coil will have greater noise than a DD.

Getting back to my testing of the GS 5. I buried a 1 gram nugget at an honest depth of 6 inches and check the signal from that nugget with three different machines, one of which was the GS 5. The other two machines were an older version of the Goldscan that has extensive modifications and a GQ clone on which I have added a form of ground balance. I used several different coils including a smaller Coiltek elliptical mono coil.

Now, the Coiltek coil caused the noisiest threshold but was still very usable. I could detect that 1 gram nugget obviously better with the GS 5 than with the other PI's.

I hope this helps.

Reg
 

imakeitwork

New member
Hello all. My recent experience is with a Deepstar3 which I've had now for about 6 mos. Let me start by saying that I truly love this machine for what it does.....pure horsepower. Now having said that, there are definately some drawbacks that come with the package. I live in South East Florida where cell towers, antennas and every other sort of interference device is plentiful and it is definately a struggle some days to use my Deepstar. I hunt the beach and I would say that typically I have to tune the machine down 50% of the time in order to make it tolerable. Now I want to make it clear that this is not just a problem with the Deepstar. I have 2 other PI's inlcuding an Aquasearch and they all suffer from it. The problem with the Deepstar is that it pumps out a tremendous amount of power and is much more sensative in general so likewise it is much more sensative to EMI/RFI interference.
I have recently taken some steps to help eliminate this with partial success. In the following photo you can see that I shielded the entire inside of the case with and EMI/RFI shield coating that is well grounded to the board. This helped..... but upon more testing I find that the majority of the interference is picked up by the coil itself....no suprise.
The bottom line is this, I have certain beaches where I know I can use the full potential of the machine and others where I don't bother because I would have to tune it down to far and that's like driving a dragster in a 15mph speed zone all day.....what's the point.
The machine is awsome and does what it says, but you can't control what goes on around you. I guess that's why I have 4 other machines...at least that's what I tell my wife. :)
 

gatorguy

New member
I have heard of putting aluminum tape inside box, whether that will help beyond what you have done I don't know, just an idea. Don
 

Eric Foster

New member
You are a brave man to strip it right down :clap:I was relying on the fact that the circuit board is sandwiched between two grounded aluminium plates but, the conductive coating on the box can only improve matters in areas of high em interference. However, as you say, this won't help with noise that is picked up on the coil.

The noise performance of the Deepstar does not necessarily relate to the Goldscan 5, however. Much more development had to be done on the GS5 to get noise levels lower, especially now that we have added channels for ground balance in the receiver. This basically relates to more sophisticated filtering all the way down the RX chain to achieve this. Coil pickup would be about the same on both machines, but the GS5 may well be untroubled by much of the interference in your area. We can only say for sure, when someone uses a GS5 in SE Florida.

Eric.
 

gatorguy

New member
another idea, if you are running at minimum delay(10Usec) and using the detector in the water, you will probably need to reduce the Pulse Delay to around 15Usec, maybe you are picking up the salt as a signal and not so much other interference? I lived in Daytona and have used most brands of PI's including Erics, all which ran at 15Usec with Mono coil and never had any problems in or out of water and A1A was right back of me with all the condo's and other commercial buidings. If you can't turn the Delay up and/or threshold down, then I guess you do have to find a better day to hunt! LOL....Don
 

Eric Foster

New member
If it is coil pickup, then making a figure of 8 winding will quieten things down a lot. There is always a trade-off though. Depth will not be as good and the coil response takes a bit of getting used too. Coins and rings tend to give a sharp null when passing under the centre.

Coil making is not that easy, particularly as you need to shield it, but some detectorists are hooked on it. bbsailor, who posts here and on the GeoTech Forum is one of them. Also CharlesNY who makes some super shells.

Eric.
 
from hordes of other detectors roaming 'your' beach, simply build an 18 inch coil, crank your machine to max and occasionally aim it up and down the beach. You'll keep a 200 yard strech of beach clear of those freeloaders.
 

fredm

New member
Steve, I have used my GS-5 at Coronado Beach which has a military base at the north end. I have jets approaching the airstrip flying just a few hundred feet over my head, they are constantly taking off. Just a few miles away is the San Diego Airport with plenty of take-offs and landings...no problems there either. The only thing I noticed was when walking over some type of underground cable the machine gave a slight distortion or warble. This was adjusted out with the frequency control...I am looking forward to getting it back from it's visit back to England.......For stability of operation I diffinitely give the GS-5 a big thumbs-up...
fred
 

Mr.Bill

New member
Well, thank you. :please:

I'm not so certain about the power of the Infinium being very high. Not to take away from a nice detector such as the Infinium, but it's not a high powered unit as your older Goldscan. With the Infinium they have managed to get real good performance out of a low power unit. There's a lot to be said for that. The Infinium is a under-rated detector that should be enjoying more popularity that it has.:thumbup:

Mr. Bill
 

Rudy

New member
I recall having read someplace that in the USA the FCC requires that the coil transmit power must be limited to a certain number of miliwatts.
 

willy

New member
Seeing as the coil is being swept above the ground, and it is radiating in all directions, I'd think that it should be considered air to air. Also, if it was restricted to the ground there wouldn't be any trouble (interference) between detectors. Such, alas, is not the case. I remember not being able to get within 30 ft of my buddy's Infinium with my MXT when out prospecting. ..Willy.
 
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