Anti interference coils

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Anti interference coils

Post by toad on Sun 22 Feb 2015, 9:29 am

Anyone using the Coiltek 11" AI coil on salt with a 4500?

If so can you tell me how it performs and what basic setting you use?

Toad
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Re: Anti interference coils

Post by martinjsto on Sun 22 Feb 2015, 9:58 am

hi toad, i have not used one personally but remember reading a thread from a fellow who was using it in the salt lakes. i will try to find the post for you,



edit:
here ya go, some usefull info

http://www.detectingwestaustraliangold.com/t3681-ai-coil-salt-settings?highlight=ai+coil

http://golddetecting.4umer.net/t12465-dd-anti-interference-coils?highlight=anti+interferance

http://golddetecting.4umer.net/t3497-14-coiltek-anti-interference-coil-for-salt-and-high-mineralised-ground?highlight=anti+interferance
hope that helps

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Re: Anti interference coils

Post by Boulder on Sun 22 Feb 2015, 8:30 pm

Will this type of coil completely cancel out EMI from an electric fence?

thanks
Boulder

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Re: Anti interference coils

Post by CrazyPete on Mon 23 Feb 2015, 5:12 am

Boulder wrote:Will this type of coil completely cancel out EMI from an electric fence?

thanks
Boulder

Yup, i used to detect within 20ft of a horse fence with no EMI at all, any closer and it started to interfere
a bit but could still detect gold easy peezy.

Havent read the above links but all AI coils need to be run in DD mode on the coil selection otherwise it
will not behave how it is designed too "ie" EMI and Salt cancelling properties.


Pete Cool

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Re: Anti interference coils

Post by Guest on Mon 23 Feb 2015, 6:34 am

Originally AI (anti interference) coils were designed to be used for detecting near or under power lines, here in WA we don't have many places with power lines where it causes us any issues but in the Eastern states there are many places that have power lines crossing through gold bearing areas, before the AI coil was produced ground close to and under the lines was largely undectable.

The power carried by an electric fence is of course a lot less than the high voltage lines, but because the power is intermittent it causes more of a pulsing effect picked up by the detector which gives you the chits driving you away, the AI coil will allow you to detect right up close, also long runs of wire will create signals picked up by the detector particularly in the warmer and windy weather, this is also a good time to use an AI coil if you have one.

At some point someone worked out that an AI coil was good on the salt lakes, more likely by a visiting Mexican that happened to have one in his kit that was being used in the Eastern goldfields or on salt lakes over there?, and now they are used widely on the salt lakes or in low lying areas that are heavily saturated with salt, that's how they came to be known as a "salt coil"

au-fever




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Re: Anti interference coils

Post by Boulder on Mon 23 Feb 2015, 1:07 pm

Thank you Pete and au-fever for your replies to my question.

I asked the question for info on how an A1 coil would operate within range of an electric fence since I do not own one.

Not having received this type of interference previously I had no idea what was causing the spikes, which although similar to a lightning spike, the regular intervals had me wondering could this be from an electric fence as there was a fence line running beside the dirt road that passed by the nugget patch, around 75 to 100 metres away.

Walking over to the fence I noticed a length of separate wire running through white insulators.

I have also tried using a DD coil in Cancel mode on the GPX over the patch but still the spiking persisted.

Therefore would a A1 coil still do the job to cancel out the spiking problem?

Boulder


Last edited by Boulder on Tue 03 Mar 2015, 8:29 am; edited 1 time in total

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Re: Anti interference coils

Post by CrazyPete on Mon 23 Feb 2015, 1:49 pm

An Anti-interference coil will kill the spikes from a stock fence but it could be the case of each different brand of electric fence might have a different op frequency and that might not be fully 100% blocked out, but will still settle down all PI detectors by 80 - 95% which allows higher gain and a better distinctive response to targets..
Best if you have a mate who would lend you one to try, IMO all prospectors should have at least a 11"AI coil in their kit, the favorite size is the 17x11AI

Pete Cool

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Re: Anti interference coils

Post by Boulder on Mon 23 Feb 2015, 4:10 pm

Thanks again Pete and yes will have to get one to try.

I was also going to ask what sizes the A1 coils go up too ?

Boulder

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Re: Anti interference coils

Post by CrazyPete on Mon 23 Feb 2015, 5:42 pm

Boulder wrote:Thanks again Pete and yes will have to get one to try.

I was also going to ask what sizes the A1 coils go up too ?

Boulder

11",14",18" 24" Round and 17"x11",24"x12" Ellipticals, and the big daddy of em all the Drag coil 1mtr x 0.5mtr
At least they were the sizes made while i worked with Trev at Coiltek Wink
17"x11" is the smallest Ellip that could be made without the windings seeing each other, would have loved a 10x5 Ellip AI sniffer coil but no-go, times may have changes on the above coils since then, type in Coiltek manufacturing.com.au and check their products
list, good tuff gear that performs really good out bush.

Pete Cool

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Re: Anti interference coils

Post by Boulder on Mon 23 Feb 2015, 6:54 pm

Pete that is a good variety of sizes.

Btw does the an AI coil display similar depth to a DD coil with the same dimensions?

If so then would say an 18" AI coil be required to produce a similar depth to a 14" mono?

And as you go up in size with a AI coil is it then less effective at cancelling EMI than a smaller AI coil?

Boulder

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Re: Anti interference coils

Post by toad on Mon 23 Feb 2015, 9:00 pm

Thanks guys. Gives me somewhere to start. I picked up a unused Coiltek 11" AI coil off Gumtree for $150.00 so I'm happy. Was going to buy one last year but didn't get around to it.
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Re: Anti interference coils

Post by CrazyPete on Tue 24 Feb 2015, 5:53 am

Boulder

They are roughly a tad more sensitive than a DD but can be troubled by bad mineralization, but they are not made for cancelling mineral just salt and EMI.
The 18" will give very similar depth to a 14" Mono, but like any other coil it will need to be ground balanced very accurately to get optimum performance and depth.
There is no difference in their Cancelling ability no matter what size or shape.
If i had to own just one AI coil it would definitely be the 17"x11" for its ground coverage, depth, and sensitivity with that depth.
Good luck with your choice man, they are a very good coil.

Pete Cool

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