GPZ 19 Accessory Coil - Coming Soon!

[goldenoldie]

5 hours ago, RedDirtDigger said:

Since upgrading from a 4500 to a 7000 I have had to drag the crowbar out of the truck to dig holes many more times compared to when I used the 4500. cheers RedDirtDigger  

Are you are speaking about having to punch through hard cap rock with a crowbar instead of digging way deeper holes compared to the 4500?

Would love to see some pics RDD of those holes you speak of that you have had to dig with a crowbar.

[RedDirtDigger]

4 hours ago, goldenoldie said:

Are you are speaking about having to punch through hard cap rock with a crowbar instead of digging way deeper holes compared to the 4500?

Would love to see some pics RDD of those holes you speak of that you have had to dig with a crowbar.

Hi Goldenoldie, The crowbar was for digging in hard clay with quartz debris in it and other hard soil locations. . I have been digging targets  2 feet deep and deeper with the Zed regularly and a crowbar is a must in some ground types. All the very deep crowbar dig targets I have dug with the Zed were scrap iron from the 1850's diggers unfortunately. The deepest piece of gold I have found Zed was around 20-24 inches deep....a 3 ouncer. 

 

[AussieMatt]

I think the GPZ19 coil will be a weapon but still not sure I need one yet

With the standard GPZ14 coil I dug a piece of very old rusty steel that looked to be a bit off some sort of steel strap. It measured around 100m-150mm long (4"-6") x 25mm wide (1") x 3-4mm thick (1/8"). From the surface it was a very faint signal & I wasn't really sure it was anything to start with but once I got digging it soon brightened right up. I ended digging down to about 600mm (24") until I struck tree roots which I couldn't break with my pick due to depth/angle. At that stage I was getting hopeful but after returning with the camp shovel & cutting through the roots out popped the rusty junk. My pick handle is a measured 900mm long (36") & guesstimating the final depth I'd say it was at least 700mm down (28"). The ground at this spot is fairly mild & mostly pretty easy digging but there are some very hard, compacted clay areas or even layers too so I can definately see the need for a good shovel or digging bar.

It's an hour or so of my life I'll never get back but the anticipation of what might be is what keeps us going back for more - I think  I can only guess at this stage but you would have to say the GPZ19 coil will get better depth than that?

[goldenoldie]

Thanks RDD for your reply and the pic of your nugget.

Unfortunately Iron and Steel produce a better response than Gold.

[schiara]

I just have one question, when will the new coil be available in the USA. I'm inching to get one as soon as possible. Anyone have any ideas of when.

[Tortuga]

On April 26, 2016 at 3:50 PM, goldenoldie said:

Thanks RDD for your reply and the pic of your nugget.

Unfortunately Iron and Steel produce a better response than Gold.

I know you're right but isn't gold denser and more conductive?

Does it have something to do with iron and steel being refined metals or maybe just how they're found? Considering if a nugget is still "in situ" and not sitting in an old tailing pile or pothole, it can very be ancient and may have occupied a bedrock crack or clay bar for thousands of years. It should have a lot more clay and soil built up around it than a piece of iron or steel dropped or tossed 50-100 years ago. Maybe that's why manmade trash targets are typically louder and don't have that soft, quiet tone like some gold nuggets. 

[Norvic]

Yeah, solid gold is more dense and more conductive but ferrous objects because of time have corroded and leached into their surrounds unlike gold which is basically inert thus no "halo" whereas old ferrous objects have a halo. You`ll note this when you disturb that halo whilst digging ie the signal decreases.

[Steve Herschbach]

Metal detectors react to conductive targets or magnetic targets. Iron and steel having both conductive and magnetic properties present a metal detector with a double wallop.

[Randy Lunn]

With the new 19" coil it will be interesting to see the trade-off between small gold sensitivity and depth. The new ZVT (Zero Voltage Transmission) technology does not seem to as sensitive to the traditional trade-offs. Understanding the shape of the larger coil's "sweet spot" will be interesting too. Will power consumption be the same? Where will the trade-offs be?????

[robby_h]

Metal targets are represented as a coil with L (inductance) and R (resistance). The time constant is L/R (large bulky objects have a long time constant and small targets have a short TC).

The magnetic properties of iron enhances its inductance, which in turn increases its time constant making it appear to be much larger than it is.

For those interested in further reading download the following article by Bruce Candy, page 4.

http://www.minelab.com/__files/f/11043/KBA%2000-1%20Metal%20Detector%20Basics%20and%20Theory.pdf