Iron bias

Can someone offer me a simplified explanation. Ive just bought the 6inch coil and cant seem to get my head around iron bias

Thanks.

Good link here Fossiker.

https://www.detectorprospector.com/forums/topic/5267-iron-bias-what-it-is/

In heavy iron I would be more inclined to increase recovery speed to improve separation rather than use Iron Bias. And to be honest I have never adjusted Iron Bias from factory as I wonder if it will result in missed non-ferrous targets. This is backed up by nothing more than me guessing!

If raising Iron Bias just means that large pieces of iron that can often present with a non ferrous tone also are more inclined to just sound off as ferrous then I am happy to leave it at default. Digging the odd axe head or pick head or large slab of steel isn't that much of an issue for me and sometimes they are a nice item.

Cheers, N.E.

Northeast said:

Good link here Fossiker.

https://www.detectorprospector.com/forums/topic/5267-iron-bias-what-it-is/

In heavy iron I would be more inclined to increase recovery speed to improve separation rather than use Iron Bias. And to be honest I have never adjusted Iron Bias from factory as I wonder if it will result in missed non-ferrous targets. This is backed up by nothing more than me guessing!

If raising Iron Bias just means that large pieces of iron that can often present with a non ferrous tone also are more inclined to just sound off as ferrous then I am happy to leave it at default. Digging the odd axe head or pick head or large slab of steel isn't that much of an issue for me and sometimes they are a nice item.

Cheers, N.E.

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Thanks mate

The more I read the more Im inclined to leave it alone as you suggest. Good link appreciate it erfect:

Try field mode 2 with factory settings if you want to see what effect reduced iron bias has. I've found that even a large rusty square nail will give a 15-16 TID in this mode. I have set iron bias to 6 across all modes on mine and as northeast said, increase recovery speed in trashy areas cos the iron will still mask good signals with recovery speed low, even if it's not giving off high tones. Swing around the area in all metal mode to see how much iron junk is in the ground.

Dave79 said:

Try field mode 2 with factory settings if you want to see what effect reduced iron bias has. I've found that even a large rusty square nail will give a 15-16 TID in this mode. I have set iron bias to 6 across all modes on mine and as northeast said, increase recovery speed in trashy areas cos the iron will still mask good signals with recovery speed low, even if it's not giving off high tones. Swing around the area in all metal mode to see how much iron junk is in the ground.

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Ok will give field 2 a crack. Thanks Dave.

In basic terms, the higher you set Iron Bias, you are wanting the detector to really reject iron. The lower the iron bias, the more cautious the detector will be around targets it thinks may be iron. It is pretty much a similar thought process with Iron Reject setting on gold detectors.

Dave79 said:

I have set iron bias to 6 across all modes on mine

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My understanding is that is incorrect for what you trying to achieve?

Surely you need to run it with a low iron bias of say 1 or 2 and what that does is you will get a few false positives ie you get a signal of 15 or 16 which will turns out it's a rusty nail, but you will miss less good targets...

As you increase the iron bias, you will get less false positives, but you might miss some good targets that the machine is not sure about so now rejects them as iron???

As I understand it, the cleaner the ground the lower you can run iron bias....if the ground is full of iron junk, you tend to run a bit higher iron bias to cut down on the amount of junk you are digging...

Edited to add, in trashy area you need to increase your Recovery Speed on the detector to help give the machine a chance to separate the targets, but the down side of doing this is that you will get a little less depth..

Physically swinging the coil slower over the target can also help as can approaching a suspect target from different directions...

Ideally if a good target is next to a bit of trash, you get the best results if your coil approaches such that it goes over the good target first, then the trash...the closer they are in the vertical plane the more difficult things become...

Yeah, it's probably on the high side but most of the places I detect are old prospectors huts and settlements made from the plentiful timber in Tassie so if you're going to dig square nails you won't cover much ground in a day. The ground is also quite mineralized and if you drop iron bias below 3 you will dig up an awful lot of red rocks :awful:

Dave79 said:

Yeah, it's probably on the high side but most of the places I detect are old prospectors huts and settlements made from the plentiful timber in Tassie so if you're going to dig square nails you won't cover much ground in a day. The ground is also quite mineralized and if you drop iron bias below 3 you will dig up an awful lot of red rocks :awful:

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That's sounds like a workable compromise for digging trashy ground..We don't get anywhere near the natural ground mineralisation as you guys, but we do get a lot of coke which throws up its own issues...

I feel your pain re trashy sites...Thearea I hunt boomed in the late 1700's through to early 1900's so there are a lot of old coal mines, brick works and similar heavy industry which has long since gone leaving lovely looking farm land that is infested with iron...There are lots of junk finds for that period but those plus the iron trash, make trying to get back to the interesting stuff that is pre 1500 really difficult..