These coils were originally produced for the SALT LAKES in Western Australia but have become a great search tool for many areas around the world. They have excellent depth capabilities which is why they are such good patch finders but their sensitivity to smaller targets, 1-2 grams and below, is greatly reduced. For a 1-2 gram piece to be heard it would need to be on the surface and the coil detecting speed quite slow. However, finding the small pieces is not what this coil is designed for!
The 40 x 20 coils do take a little time to set-up and get right in regards to towing / dragging but their performance is very good once achieved. The main thing to remember is to protect the cable from any snags or pulls from low lying bushes and rocks. Clear, flat terrain is best. The coil can be around 1-2inches off the ground depending on what you make the coil housing out of and remembering that the coil needs to remain connected to the housing to prevent the bumps of normal travel dislodging the unit. This can be achieved by cable ties or nylon nuts and bolts. The coil housing is best made from timber as is the arm which connects the unit to the quad bike. The skids for these coils can be made from tough, durable plastic or conveyer belt material.
Just remember that some material can have wire re-enforcing inside it so if you’re unsure, just wave the material to be used over the detector coil first to see if it ‘sees’ the material. If you are dragging this coil by quad bike we recommend your speed to be about 5-7kms/hr which is like walking pace or idle engaged with 1st gear and obviously picking a relatively clear path. The Coil needs to be around 3 metres away from the bike. This will provide quieter operation. If you are dragging the coil behind a person or using a trolley set-up then this the same speed applies, just be prepared for some hard work!
When setting this unit up on the skid you must ensure this area is protected from anything which can pull or damage the cable. By cable tying the cord down after it comes out of the coil, ensuring the cable is not at a very tight angle to the exit point, you will prevent any damage in this area. Remember A.I. coils can get a little noisy due to ground conditions so the slower the better. We hear of people using little flags or coloured spray to mark targets heard when on a run to minimize the times they get on and off the bike. Having a handheld unit close will help you identify the target quickly and if you work with a partner then one can patch find and the other can retrieve the signals heard.
Available in ANTI-INTERFERENCE (A.I.)
ANTI-INTERFERENCE (A.I.) operation hints & tips
This is the coil of choice when hunting the Salt Lakes or dragging the coil behind a quad bike and you want to cover lots of ground quicker than a hand-held set-up. It has good sensitivity and has the ability of punching deep into the ground. This coil is not the tool to use when pinpointing so a smaller handheld coil would be recommended for this. As these coils are fully epoxy filled (potted) they are very robust and rigid so can take some hard work however the cable entry point on the coil is the most precious part. They have a similar coverage area as a DD so a ¼ overlap is recommended and a slow travel speed is best. Running the coil in standard DD settings on the later model detectors will ensure the coil performs as it should. Remember the most responsive area of the coil is the centre spine so with experience you will be able to master this coils ability. If you require further information on your set up or use of this coil you are welcome to contact us to discuss it further.
Great for deep searching
Very robust coil
Good for open terrain searching
Great ground coverage
Good stability when motion is slow
Best used in drag format
Applicable metal detectors
Minelab SD Series – Best Suited
Minelab GP Series – Best Suited
Minelab GPX series