coil mods

[Justin E]

Is it possible to modify the receiving coil in a search coil to make a detector more sensitive and better able to see deeper? I know most vlf detectors transmit deep but cannot receive deeper signals well.

 

[JohninNC]

Most coils are sealed in such a way that it would not be a good idea to open it. Depending on your machine there could be better coils available. Smaller coils are usually more sensitive, but not deep. If you want deep targets, then a larger coil is the way to go.

 

[Justin E]

Thanks! I'll ponder on it a while and see if I can figure it out.

 

[GoGoGopher]

Coils are sealed in epoxy resin most of the time, so not able to alter them...
Easiest way to mess around with your own coils is to build a PI kit and build your own coils...
That is a little beyond my knowledge of electronics though...

HH,

 

[Justin E]

Mine too, for now. What I might try, when I can afford it, is get some used coils off eBay and try taking them apart...

 

[Justin E]

Some people say the depth and sensitivity issues are from the discrimination programming. Is there a way to alter it?

 

[JohninNC]

Discrimination will quickly reduce depth. I hunt with an MXT Dis=2 and get enough depth. I also have experimented with coils. An easy way to start is to put a request out on the forums for broken coils. I got some by just paying the shipping. I have also repaired some, so the best way to do it is to use a dremel tool and carefully cut the coil in half by cutting around the seam. Gently separate as some coils have what they call a 'tickler' or fine tuning wire. It is usually connected to the ground side of the receive coil. It is a wire (usually about 30 gauge) that is moved to the exact position to get resonance or balance between the receive coil (RX) and the send coil (TX). This wire can also increase sensitivity and is often used on a large coil to make it more sensitive. (Smaller coils are more sensitive inherently just because they are small). Problem with small coils is they are not usually that deep. The rule of thumb is a coil is normally only as deep as it's widest point. Like a 3" x 6" would be about 3" deep. Some coils are better and you can get better results. What machine do you use?

 

[Justin E]

I'm looking at getting a GTI 2500. I've just heard it's not sensitive on smaller coins.

 

[JohninNC]

I don't know about the GTI 2500, but I have friends that have Garrett's ACE 250 and AT PRO and both are great machines. They find lots of coins and relics with both of those machines. Maybe someone that owns one can give you more info.

 

[Justin E]

I've had a hard time getting GTI 2500 owners to really comment on their detectors. I've even asked questions on dedicated forum sites, only to get little to nothing. I did have a guy in Serbia, I think it was, on the geotech said he could get around 13-15" in all metal, if my conversions were correct. While he loved the detector overall, he did say that it was harder to get smaller targets and depth on the discrimination because of the rigid discrimination programming. I'm not certain if he had trouble with smaller coins and such in all metal or not.

Another guy said I could try playing with the electronics to try and get about 10% more depth, but I'm not certain if that'd increase sensitivity to smaller objects. There has to be a way.

Also, does anybody know if there is some way to make a DD imaging coil? I've heard some say there is and others that there isn't. What's your take?

 

[JohninNC]

The whole key to imaging coils is configuration. There is a lot of different types of coils out there, but with experimentation I think we will see more and better coils in the future. I use Whites MXT and I like the machine and the number of different coils available for it. I think there is currently 24 different coils available for the MXT. Garrett will not sell any of the special connectors for the AT PRO, it will limit the number of coils available for it. I suspect that ground penetrating radar will be the next big change in metal detecting. It will require a different coil that will allow information on a X, Y, and Z axis so you can get a three dimensional view.

 

[IXL]

JohninNC, Can you give me information about the Big Dawg coil as i see you list owning one?
I don't mean to hijack this thread but i didn't see a thread for questions about coils.
Thanks in advance.
HH

 

[Sven]

You can visit the coil building forum at Geotech

 

[IXL]

I'm trying to find out how well the Big Dawg coil works! And JohninNC is the first person i have seen that has one. I don't want to make one! I just wanna know if it's worth buying. Thanks!
John

 

[lukeaa]

I emailed the Big Dawg group yesterday. Here is their reply:

"The BIG DAWG Coil is not V rated at this time. It will work with the lower two frequencies but has not been tuned or tested for the 22.5K Hz. We plan to add an 'About Us' page on our website. Thank you for your interest in the BIG DAWG Coil.

Pinnacle Design Inc."

 

[stasys]

Take coil apart and investigate--maybe you will learn something.

 

[CROCK of COINS]

I will have The Big Dawg Coil in a few days...Let the FUN begin I have 3 BigFOOT coils...now to compair--Eagle SL II/BigFOOT, XLT/BigFOOT, DFX/BigFOOT and the VISION/BigFOOT soon to try the Big Dawg Coil ;-)

pinnacledesignnc com


Jerry