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Cutting it fine with small coils

April 17, 2012 09:23am

Mark Williams
Mark Williams metal detecting blog posts

The Challenges

Everyone that detects parks, ovals and old sites for coins and relics know that sometimes it is almost impossible to detect where there is a multitude of bad targets in the ground. These trashy areas will wreak havoc when using larger coils as they can mask the good targets often found in close proximity to rusty iron, pull tabs etc. Most of the time I use the 11-inch Double-D stock Minelab coil with my E-TRAC, but recently I have been challenged by a couple of friends to give a smaller coil a run and see if it is better in these situations. My weapon of choice was the 8-inch FBS 800 coil from Minelab and for it to be a fair test it would have to be in an area that had really been given a thorough going over with the 11-inch coil while using the same settings. There is an old blacksmith shop that would be perfect, because one side of the house is extremely trashy but I still managed to pull some good targets out with the bigger coil.

Tuning In

I was reasonably confident that I wouldn’t have missed much, if anything, knowing that I had been over the spot quite a few times going low and slow. This type of detecting needs extreme concentration as you have to really shut everything out and tune in to every little response that potentially could be a good target masked by rusty iron.

I had chosen to operate with an open screen, only discriminating out the lower 5mm of the screen where iron targets are obvious. You can also discriminate out the top of the screen from 1:1 to 1:39 which will reduce some noise from the halo created by rusty objects. Now it is a case of going really slow and listening for familiar tones of good targets as you move past the rubbish. It didn’t take long for me to realize that there was something very different about using the 8-inch FBS 800 coil, it was like a fine blade moving between the targets with precise accuracy. I was surprised when the good targets started to stand out leaving me wondering how I had missed something so obvious, so I started to take notice of what was around the target and how far away. It was apparent after a while that every target had rubbish outside of the 8-inch coils reach that would have been picked up by the larger coil causing possible masking.

Old Sites & Parks

This small 8-inch coil has proven its worth to me in the trashy areas of ovals, parks and old sites after only a few hunts. It has awesome capability in discerning between the ferrous and non ferrous targets with ease, as for depth there were a couple of targets retrieved at around 6 inches and I am confident that it will go deeper. I finished up with two Britannia pennies an 1890 and 1891, an old thumb bob, a musket ball, some other relics and a very high opinion of the small 8-inch FBS 800 coil that will always be close on hand. So think of all the places that you could go back over where you may just have happened to miss a choice coin or relic, I don’t know about you, but I now have year’s worth of quality places that are now detectable.

Mark Williams


Hi Mark,
I'm wondering, in sites that are so full of ferrous, do you always run Fast Recovery ON, and Trash Density HIGH?
And these coins seem to be fairly shallow, so I'm guessing you could run your Sensitivity quite low and still see the coins?

And finally, leave some coins for me! :-)
Posted By: Nenad on April 17, 2012 11:46am
Hi Nenad, I did run in fast recovery on and Trash density high. The reason I run in fast recovery is to maximise the recovery in the the response time as you slide off the edge of trash you want the E-TRAC to be ready as quick as it can to pick up any target that is borderline being masked by the iron. I love this feature and believe that it increases your chances of locating good targets amongst the trash. High trash is a must as far as I am concerned because it will lock on to the strongest and most consistent target, this coupled with fast recovery gives you the utmost chance of hearing a good targets that could easily be overlooked. When it comes to sensitivity, I trust the E-TRAC's ability in auto and usually run in +3 but here I may go down to +1 depending on how much trash is actually in the ground. Hey and nothing personal but I hoover as much as I can. Just let me know when you want to get out for a hunt and we can compare notes thanks Mark.
Posted By: MarkW on April 17, 2012 06:11pm
starting to hunt with my X-TERRA 705 and 9" Concentric in a park but wonder if I should just start with my 6" Double-D instead? can you give me some pointers please. Thanks Paul
Posted By: stubfingers on May 21, 2012 11:57am
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