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Tow Coils / Drag Coils


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Reg, With the set up I saw years ago, 2 guys rode on the quad bike, 1 drove the other had a scab-id of spears, when they had a signal, the non driver thru a spear in the ground to show the site of the signal, when they ran out of spears they got out their detectors to detect near the spear sites. Is that what you did? ( If this is illegal in Oz don't comment)

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A couple of points when sledding.

Noise suppression coils sacrifice sensitivity for quieter use.

Longer cables equal less efficiency. 

The old KISS principle is best (keep it simple, stupid)

The sled that I still have works best in conjunction with the GPX4000 running on sensitive smooth. I have tried other models but for some reason the 4000 is the best. The 38" round mono easily picks up .22 slugs at 5KPH with a clear unmissable signal.

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What is the optimal orientation of the coil when dragging?

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Simon, the problem with your magnet idea is that it would soon be clogged with stones with a high iron content.

Mitchel, the beauty of using a base of conveyor belt is that the coil sits flat and parallel with the ground. this makes for good ground tracking. When used on pasture the grass is flattened by the weight of the belt keeping the coil as close to the ground as possible, but the grass stands up again once the sled has passed over it.

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5 hours ago, Reg Wilson said:

Mitchel, the beauty of using a base of conveyor belt is that the coil sits flat and parallel with the ground. this makes for good ground tracking. When used on pasture the grass is flattened by the weight of the belt keeping the coil as close to the ground as possible, but the grass stands up again once the sled has passed over it.

Reg,

I guess I was also interested in the 'angle' the coil was fitted on the sled.  I mean we see coils like a clock so to speak with 12 o'clock being the top.  I was always told to not push a coil but to swing it.  That would mean you want to have a 3-9 o'clock motion for the electronics to be optimal on a round coil.  This would only happen if one is standing still.

Sledding would allow for a target to come in a 3 o'clock or 2 o'clock or anywhere o'clock.  Does it make any difference to the detector?

Some coils are said to be tip sensitive if elliptical so I would think that type of coil should not be used for a sled.  You want an even field with just audio (headphones or speakers) sensors or would a digital strength screen help to identify a target outside of the noise of the tow vehicle.

Maybe I'm just making it too complicated.  

You put a round coil on a sled and when it goes over metal it sounds off and you mark the target, right?  Then you go back and see if it is a good target or not so good.

I know the meteorite men used a very large sled to find giant meteorites in a Kansas field.

Mitchel

 

The Meteor Farmer | WIRED

 

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In most of the country I detect in because of grass height, you are often pushing the coil along a brumby or cattle trail, only a foot or so in width, very little swinging. Many patches have been found "linear" detecting, I suspect because these trails follow the easiest path for the brumbies/cattle to traverse they also go across most likely places for a reef to have shed. Reg Is this so with tow coils? ie. the pulling vehicle follows the easier path thus increasing the chances of gold. 

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I have not used an oval or rectangular pulse induction coil, only round ones, and this means that the horizontal placement of the coil is irrelevant and usually decided by the position of the lead. The shorter the lead the better the performance, so the point at which the lead enters the coil should be orientated as close to the tow vehicle as possible.

With a large round coil shallow or surface targets will give a double 'beep' as the windings pass over, whereas a deep target will give a broader single signal (whuuump). Unlike swinging a coil, where a signal can be tested by multiple sweeps, sledding only gives you one opportunity to analyse that signal and decide whether or not to mark it. The occasional false signal from bumps or EMI spikes can be a nuisance, but good tight fittings will keep these to a minimum.

In the vast areas of Western Australia a sled can be used as a prospecting tool, following reef lines, patches of quartz, or tertiary gravels, whereas in Victoria it is mainly a means of eliminating planned areas by systematic gridding.

One definite advantage of tow detecting is that paddocks of crop stubble or long grass can be scanned which would be impossible with a hand held detector. The sled simply folds flat the flora without causing damage and it stands up again after passing over it.

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