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GPX 5000 With Double D For Under Powerline Work


Guest Jennifer

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Guest Jennifer
8 hours ago, Randy Lunn said:

Wow, fantastic videos. This solves a real problem I have been struggling with. Thank you.

Glad I was able to help Randy :biggrin:

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I remember being under power lines in Quartzsite soon after I got my Zed.  I didn't know any better so I just made it quiet any way that I could. (I used the auto tune right from the factory and then turned down the threshold.)  It was quiet.  I then took the test nuggets I carry with me and I could still hear them.

There was only one problem.  I found lots of trash but no gold under those lines over by Tom Wells Road.

Mitchel

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We tried a few different coils under powerlines. Hands-down the best is the stock DD coil. It was far superior to other brands by a long shot. Simply run cancel with the sensitivity as High as you can handle it, and you'll be amazed with how sensitive it is. 

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Guest Jennifer
3 hours ago, kiwijw said:

Hi Jennifer, Gosh....I haven't used a DD since my GP 3000 days & the only reason I did in the goldfields was under high voltage power lines.  

Here is a link to your exact query Jen. JP tells you what works for him.

http://golddetecting.4umer.net/t2963-gpx-5000-under-powerlines

Good luck out there

JW:smile: 

JW

Thank you for taking the time for such a detailed write up, and the link, it's very much appreciated fine sir.

Jen 

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Guest Jennifer
3 hours ago, benzyoc said:

We tried a few different coils under powerlines. Hands-down the best is the stock DD coil. It was far superior to other brands by a long shot. Simply run cancel with the sensitivity as High as you can handle it, and you'll be amazed with how sensitive it is. 

Thank you

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I agree 100% with Kiwijw. DD coils are very under rated because all of the"experts" disdain them and only use monos. I have stenciled "Mono coil" on all of my DD coils and wear a Groucho Marks disguise when I use them.

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Comment on kiwijw's post. All DD coils normally have a transmit and receive coil. Since the receive coil does the heavy lifting, and since in a DD coil the receive coil is about 60% the size of that in a mono coil (where one coil alternates as transmit and receive) all DD coils are at a theoretical disadvantage. However, a DD coil has inherent ground canceling properties that means they were the coil of choice for SD series detectors on into the GP series, though it started to change with the GP. It however was not until the GPX appeared that mono coils really became more favored with prospectors since it has timings designed specifically for their use.

It used to be the GP detectors only came with a DD coil, and the descriptions of mono mode in the manuals are actually talking about what happens when you run a DD coil in mono mode, which was the original intent of the control. The DD/Mono/Cancel switch first appeared on the GP 3000. Actual mono coils are mentioned more as an afterthought (see below).

You can run a DD coil as a mono coil by flipping the switch from DD to mono on models that have the DD/Mono/Cancel switch, in which case one half transmits while both receive. This means one coil half (the left) is both transmitting and receiving, the classic definition of a true mono coil.

Cancel is a different setting that works by reversing the polarity of the two DD coil receive halves, which results in EMI mitigation at the cost of some loss of sensitivity - if you use it where you don't need it. If it makes the detector work where it did not work previously, is that not a gain in depth?

Both Mono mode used on a DD coil and Cancel mode will pinpoint left of center.

From GPX 4000 Owner's Manual pages 44-45 (click to enlarge)...

Plus read this excellent Coil Essay by Nenad Lonic

minelab-coil-dd-mono-cancel-switch-control.jpg

minelab-coil-dd-mono-cancel-switch-diagram.jpg

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4 hours ago, Steve Herschbach said:

 If it makes the detector work where it did not work previously, is that not a gain in depth?

Steve, I absolutely love the way you turn the "negative" into a Positive!  too cool!

And I used cancel on my 3500 and 5000 to good effect...under/near power lines,where others did not go.

fred

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Fred,

You also go under power lines with your 7000!

Mitchel

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