Testing Coils - Mono and DD

Hi all
This post is a continuation of a conversation on DD coils on a Gpx.I have posted the information a seperate post as I have always believed that big coils find big deep gold and that small monos would not be capable of reaching depth.I have tried to recreate my mates 35 ounce find at Tarnagulla He used a 18 coiltek DD on a sd2200d .The nugget was found at 32 inches.Dig24crt wrote along the lines that to a Jp post that seriously a small mono could compete with a large dd.Jp replied that his brother had found a 30 ounce plus at depth with a small mono.Dig24crt replied Will do inground testing>Test area wall of Ironbark Gully Tarnagulla.Machines used Sd2200d GP3000 and Gpx4000.As it is impossible to recreate the exact conditions that the nugget was found under the best result that we could come up with was a small cylindrical Pajero Jack inserted into the wall at 34inches.This gave a reponse that was comparable to the find.Coils used were Coiltek 18 dd pro Coiltek 18 round mono, commander 11 round mono.
see next post

Inground testing from previous post
The gp3000 and gpx4000 running on tracking and normal settings gave responses that would certainly make you stop and dig using the 18dd pro and the 18 mono the signal improved again By switching to fixed and deep on both machines,The sd2200 had the same result by switching to fixed and channel 2 (mono not tried on Sd2200d)
Both the Gp3000 and the Gpx4000 coupled wth the 11monos achieved a stopable signal on the same target at 27inches there was signal at 32 inches but not one that would make you dig as it was not distintive to surrounding mineralisation,but i believe that on quieter ground you would explore it.I cant give info on the ground we tested on,all i can say its probably a 5 in a scale to 10.I have a new respect for small monos Jp I will now go an eat some humble pie for tea seriously
Cheers Dig

Hi Dig was the signal better on the 18 mono or the 18dd, thanks for doing these tests as this is the sort of posts that are intresting on the forum. cheers Trumpy

Hi Trumpy
This test took hours to achieve.The hardest thing to achieve was to set a repeat of the finder of the 35 ouncer,gold in the ground has a halo,gold is smaller,so the target we buried was probably 25 percent larger and two inches deeper.We believe that both the 18 mono and 18 dd gave a response that would get you interested,but were the responses the same or was one better I believe than scientific instruments would be needed.Sure you could dig holes in the wall and match mono against dd at lower levels until one outproformed the other.But there is a big there is a big difference when you know that a target is definately there compared to when you dont know a target is there.So I can only say from the test we did on that target on that ground that the responses we got you would definately investigate it
cheers Dig

Dig24crt wrote:Inground testing from previous post
The gp3000 and gpx4000 running on tracking and normal settings gave responses that would certainly make you stop and dig using the 18dd pro and the 18 mono the signal improved again By switching to fixed and deep on both machines,The sd2200 had the same result by switching to fixed and channel 2 (mono not tried on Sd2200d)
Both the Gp3000 and the Gpx4000 coupled wth the 11monos achieved a stopable signal on the same target at 27inches there was signal at 32 inches but not one that would make you dig as it was not distintive to surrounding mineralisation,but i believe that on quieter ground you would explore it.I cant give info on the ground we tested on,all i can say its probably a 5 in a scale to 10.I have a new respect for small monos Jp I will now go an eat some humble pie for tea seriously
Cheers Dig

Interesting results Dig24crt but not surprising considering the science behind how a DD works, along with the physical characteristics etc. Thanks for getting back to the forum with your results. Thats the beauty of this hobby you are always learning something.

JP

Hi Jonathan,
It's an ask the expert question:
I just got a MXT for my better half and a ML 3500 for myself. (only in the last 2 days;-))
The MXT has 2 coils, on eliptical DD and a 9.5" (950) mono.

The ML 3500 has a single GP Series pseudo DD coil.

Not that I want to change and swap coils between the detectors, BUT, if i were to:
1. would it be ok?
2. what would be the benefit, if any?
3. what problems would I need to look at for?

Best regards
Frank

The Whites coils would not be compatible with the GP 3500 or the 3500s coils compatible with the MXT as the 3500 is a PI design and the MXT a VLF. I don't think VLF machines can use a true Monoloop coil as per a PI but a co-planer type design instead (would have to do a Google search on the way these work etc) but from memory it is a mono within a mono without any crossovers.

Hope this helps,

JP

PS with the 3500, use Mono mode in shallow areas (you can use Sensitive mode as well), if the ground deepens or the mineralisation worsens then try using the coil in DD mode along with the Sensitive timing. Sensitive will brighten the response on smaller nuggets that can be easily missed due to the less sensitive design of a DD coil.

Thanks JP,

Thanks for the info.
I have been watching your CD's, very informative.
I have been making my own (PI) detectors and coils and compared the performance to commercial ones.
Mine just did not cut it. Even the MXT was much better. Hence I invested in 2 good performers to get the
prospecting under way.

I used to bum around in Clermont about 35 years ago. Done a bit of saphire hunting, but did not know a saphire from a rock. Ahh, those were the days.

Best regards
Frank

Gday

I think that small mono coils are underated and that most users think that the bigger the coil they use the bigger the nuggets they will find.

Fact is that there is a much higher percentage of small nuggets to big nuggets and a lot of the small bits are missed by bigger coils, I regularly find nuggets in other peoples dig holes so this indicates to me the user is inexperienced or in a hurry to find the big piece, they have heard something but after disturbing the nugget from its resting place by digging around they then lose the signal, and then put it down to ground noise and move on.

If you want to increase your findings then spend more time on an area with a smaller coil, be it a dd or mono,depending on the ground conditions, slow down and check every response, then when you are happy that you have covered it well then put a bigger coil on and have another look, listening for the iffy vague type signals that are sometimes the deeper bits.

I think that in some cases the depth capability of a small mono coil is well and truly underestimated, the thing with the small mono coil is you have to be right on top of the target, or very near to it if it is at depth as it does not have the signal strength to the sides that a bigger coil has, where with the bigger coil you would perhaps hear a response from some way to the sides of the target that would get your attention so you then move in that direction until you centre over the target, with the small coil you wont get that response from the side so you are not made aware of the target and you just keep moving on,therefore missing it completely.

Both large and small coils have their uses, and one is used in conjunction with the other, once you realise this and are aware of the type of gold found in that particular spot then your finds will increase, dont be afraid to spend time on diggings and scrapings with a small coil as I have found some of my best pieces this way, sometimes in order to get the ounces you have to find the grams first.

cheers

stayyerAU