Practical tips for using the new GPZ 19 Super-D coil

With today’s release in Australia of the much anticipated GPZ 19 coil, I thought this would be an excellent opportunity to provide some practical field advice to enable early users to get the best results from this ‘beast of a coil’. I’ve been testing and refining it with the Minelab engineering team for quite some time now, and have to say, it’s worth the wait (weight), in more ways than one!

Some key points for successful GPZ 19 operation are:

• Researching the best locations
• Having realistic expectations 
• Physical comfort and sustainable use
• Fully utilizing the Gold Mode and Ground Type settings
• Understanding how a deep target signal sounds/behaves with ZVT technology 

Let’s now take a look at these points in more detail…

Researching the best locations

Targeting locations where your chances are increased will be the best approach. With the GPZ 19 this means looking for ground that has had a history of larger than 2 gram pieces at 10” plus in a reasonably confined area or working away from known ground into ground that does not have a history of nuggets being found, taking advantage of the increased depth of GPZ to allow for gold completely missed by others to come to light.  It is best to plan your sessions to target dedicated areas and then spend time methodically and carefully going over those areas.

Having realistic expectations

Using the GPZ 19 coil does not automatically mean your gold take will increase unless you're prepared to first invest some time and thought in how you go about approaching its use. You will find there is a reduction in sensitivity to small targets which means the sub 2 gram pieces are going to have to be either shallow to pick them up or you’re going to have to be prepared to go without while you wait for a subtle deep target.

Physical comfort and sustainable use

The GPZ 19 coil is heavy. There is no avoiding its weight except for coming to terms with it and then gearing up accordingly. The GPZ 7000 comes standard with a dedicated PRO-SWING 45 harness, which when matched to your body will easily afford, even moderately fit people, the opportunity to swing the coil for hours at a time. If you step outside the supplied gear, there are other available options to suspend the coil for even greater comfort. I strongly encourage potential purchasers of the GPZ 7000 and the GPZ 19 coil to select a dealer who is prepared to spend time with you setting things so you can swing the coil effectively. Comfort and ease of use are paramount to successful GPZ 19 coil operation and this is something I focus heavily on during training sessions.

Fully utilizing the Gold Mode and Ground Type settings

High Yield 
High Yield is the Go-To gold mode for nuggets ranging in size from 2 grams through to approximately 2 ounces. However, this is dependent on the shape and size of the target, for instance a specimen containing many ounces can give a better response in High Yield compared to General due to the rough nature of the gold and how that irregular surface affects the way this mode creates a skin effect (eddy current) on the surface of the target. Testing the GPZ 19 coil in the field has shown to me High Yield is very good on nuggets ranging in size from 2 grams through to 12 grams with a very good percentage increase in performance. This is down to the reduction in ground signal relative to the target signal

General 
General is better on the more solid type gold. General creates less ground noise than High Yield, especially surface noise signals such as Saturation and Salt but also general ground variation. General has quite good sensitivity to smaller targets so is probably a better choice than Extra Deep for average sized pieces. However, in Difficult ground type, General will be more prone to knock or rub sensitivity.

Extra Deep 
Extra Deep is a gold mode that is better suited for extremely large nuggets in highly variable ground. It is not a mode for the faint-of-heart and should be seen as a more specialized approach to large nugget hunting in very specific locations where very large deep nuggets have been found before.

Understanding how a deep target signal sounds/behaves with ZVT technology

The GPZ 7000 in conjunction with the GPZ 19 is a very potent combination, but target signals do not always just ‘jump out’, especially the deeper ones, they require input and interpretation from the detector operator. The smoother and more controlled you are, the better the results. Learn to trust what ZVT is ‘telling’ you. It is the fundamental reason why ‘good gold’ is coming from the goldfields all over again.
The typical settings I have used for best results are:

• Sensitivity: 9
• Audio Smoothing: Off
• Volume: 8 for headphones/B&Z Booster, 12 for WM 12
• Threshold: 27
• Threshold Pitch: 60
• Volume Limit: 8 to 12
• Ground Balance Mode: Auto
• User Button: Ground Balance Mode

For GPZ 19 users who take the time to set up their detector correctly and then listen and learn the signal responses from their own local conditions, this large coil will deliver more of the golden results you are after – just as I have experienced during the testing phase of the coil development. I’ll be following up with some more advice about settings and ZVT in general, in another blog quite soon. Good luck out there!

Jonathan Porter

Aurum Australis