custom coil for GOLDQUEST

[davidg]

would it be possible to build a 'bigfoot' type coil for a goldquest? in other words, a DD coil that is 18-24'' long and something like 4'' wide?
i dont know jack about electronics but im getting a goldquest soon and im just wanting to try something that will cover a lot of ground.

 

[Reg]

Hi David,

It is strange that you would ask that question. Yes, a coil like you requested can be made and has been made to be used on a GQ already. In fact, I used both a mono and a DD that measure about 18" by 5" and, one that is 16" by 3" my last trip to AZ.

My favorite was a mono coil that was 16" by 3 1/2". This was used on my GQ clone that does have my home made ground balancing.

You can make them yourself if you wish. They are a little tricky, but not impossible.

Coil housings are already built to meet your request. Bill Hays of Hays Electronics has one that is bout 18" by 5". He also has a 12" by 3 1/2" and just the top half of a 16" by 3 1/2" housing. His housings are not displayed on his website yet, but they are available. They are simply a rectangular form with slightly rounded corners.

The second person to make them is Charles Keith (Charles NY). Pictures of his housings were posted on the Geotech forum, but appear to be gone now. His forms are a little lighter since they are more custom in design. I am sure he can send a pic. If not, when time permits, I can take a pic of the one I made.

Reg

 

[davidg]

n/t

 

[gatorguy]

Try Geotech. Don

 

[davidg]

theoretically would a 3 foot long coil work?

 

[Largesarge]

Charles has a web site www.detectorgear.com but his coil building is under construction at the moment. I'm sure if you E-mail him he can help you out, He's nice people.

 

[Reg]

Hi David,

You should be able to get a 3 foot long coil to work on the GQ but not at the minimum delay. That is pushing things quite a bit.

The larger the coil, the harder it is to build one that will work at very short delays. So, there will be a loss of sensitivity to the smaller stuff or items such as small gold which are in the lower conductive range.

The 18" by 5" coil is about the same is trying to get a 13" round coil to work at the short delays. Even one this size can present some serious problems to get to work right at a delay of 10 usec.

My guess is a 3 foot coil by 5" would be similar to about a 24" to 25" round coil, or something reasonably close to it. Right now, I have no idea as to what the minimum delay such a coil would require to function properly. I just know, I would prefer to not swing it all day.

Personally, the 18" by 5" is more than long enough for me.

Reg

 

[Reg]

Hi David,

There has been quite a bit of information about building coils for Eric's machines on this forum. You will just have to do a search for that info.

Now, as Don mentioned, the Geotech forum has a lot of information about coil building for a PI also. In fact, they have a specific area of information dedicated to coils and coil building. If you read a lot of this information you should have more than enough of an idea of where to start.

http://thunting.com/geotech/forums/

There are a lot of techniques used to try to minimize the coil capacitance, so you will run into some strange looking coils in your search. To begin with, I would recommend you stick with the basic approach of simply winding the coil, shielding it and picking the proper cabling, rather than try some exotic winding style.

Reg