Fisher F75 Strikes Gold Twice In A Row!

[Steve Herschbach]

I am a big fan of the Fisher F75 from a different perspective than most. I am a prospector and have done very well finding gold nuggets with the F75. The very powerful all metal mode combined with the simultaneous on screen target id numbers have allowed me to quickly and efficiently hunt trashy tailing piles in search of large gold nuggets. The light weight and superb balance make the F75 a pleasure to use for long hours in rough terrain. It also was my detector of choice for my one and only trip to the UK that I have done so far, and it served me well there.

I spent a month in 2013 metal detecting on Jack Wade Creek near Chicken, Alaska. I kept my great results there quiet pending a return trip there in 2014. That trip has now been made but that is another story already told in detail on my website. Now I can finally reveal the details of the 2013 expedition.

I started out early one morning with my big gun pulse induction metal detector, but got onto a tailing pile that had ferrous trash scattered down one side, and I was just not in the mood for it that morning. I went back to my truck and got out my trusty F75. I run the F75 in all metal because it has instant target response; there are no worries about recovery times in all metal. The coil picks up every variation not only in targets but in the ground allowing me to monitor what is going on at all times. Knowing what the ground is doing is important in keeping the ground balance properly adjusted for maximum results.

The key thing I like about the F75 in all metal however is that the meter always runs in discrimination mode and places a nice, large target number on screen while in all metal. The audio alerts me to a potential target, which I then analyze more carefully while watching the target numbers. All metal goes deeper than discrimination modes, so no on screen number means a very deep target beyond discrimination range. This alone makes running in all metal desired when prospecting because running in discrimination mode would miss all those extra deep signals.

In all metal I dig them until a target number shows up. Deep targets or small targets in mineralized ground will often read ferrous, so I watch the numbers and if they even once jump to non-ferrous, I dig. Only targets that give a 100% strong ferrous reading over multiple sweeps can be safely passed. Though I will throw in my caveat that no discrimination system is 100% accurate and there is always a risk of passing a good target. When in doubt, dig it out!

I do often employ pulse induction detectors and do very often just dig everything. I advocate that when time and conditions allow. The reality is this is not always practical for many reasons. Maybe it is just limited time and overwhelming amounts of junk. Better to increase the odds by using discrimination than bogging down digging 100 nails in a small area. In my case it often boils down to fatigue or flat out not being in the mood to dig junk.

So it was on this particular morning, and therefore my F75 came out and I got to work sorting through the trash working my way up the side of the tailing pile. I crested the top and got a strong reading and looked down. There was a shallow dig hole with leaves in it, obviously from some hunter there in prior years. I figured the guy had recovered a trash item and kicked it back in the hole so I cussed him quietly under my breath. I hate it when people do that!

Then the target numbers caught my eye. They were all over the place. A crumpled piece of flat steel might give numbers like that though. Still, I was curious and figured I would retrieve the trash this person left in the field. I gave the old dig hole a big scoop, and out pops a big gold nugget!!

I seem to have a talent for finding ugly gold nuggets, and this one was perhaps the ugliest I have ever found. It looked more like a rock burnt in a fire than a gold nugget when I dug it up, though the glint of gold is unmistakable. This gold however was very pale and in fact later analysis revealed it to be roughly half gold and half silver and other metals.

It is a little known fact that gold alloys tend to have very poor conductivity ratings. Gold is very conductive, and silver is a superb conductor. You would think adding silver to gold would improve the conductivity, but in fact just the opposite happens, and the conductivity lowers dramatically. Gold/silver alloys are closer to lead in conductivity than that of the pure component metals, explaining why bullets read identically to most gold nuggets.

This ugly nugget is a detectorists worst nightmare, because the 50-50 alloy mix and rock content give it a much lower conductivity reading than would be the norm. I surmise what happened is this earlier operator got a poor signal and gave a dig to get the coil closer to the target. The signal did not improve, as would be expected with most gold nuggets, so the operator decided it was trash and moved on. The rest of the hill being covered with junk no doubt contributed to this decision.

It was my insistence on investigating everything except 100% ferrous readings that made the difference. The readings on this target were not solid as one would expect from a pretty strong signal but all over the place. Most people would say that indicates a trash target but I have seen many gold nuggets do the same thing in mineralized ground. The result is I dug a shallow 2.33 ounce gold nugget that somebody else walked away from. Sadly for them one more scoop would have revealed the nugget for what it was. Hopefully this is a reminder to the reader that far too often detectorists look for excuses not to dig. How many good finds get left behind because we do not want to take that extra minute or two to dig a target?

This nugget is far from a premium find, but I have already sold it for over twice the cost of a new Fisher F75. That detector was a real money maker for me as that was far from the only gold I ever found with it.

Unfortunately I say was. I made a huge change in my life in 2013 and moved from Alaska to Reno, Nevada. The move resulted in a desire for me to weed down my detector collection. I was pretty excited to do some coin detecting in Nevada where the potential finds were much better than those possible around Anchorage, Alaska.

Almost all my detecting with the F75 had previously taken place in rural locations far from possible electrical magnetic interference. In Reno, EMI raised its ugly head. I found much to my dismay that the F75 did not like my new location, and in fact when turned on to hunt the yard at my new home I could not get it to settle down at all. No matter what I did the machine chirped and beeped and numbers flew all over the screen. Unfortunately I experienced what many urban hunters have found out – the F75 is a very sensitive high gain detector that does not get along well with electrical interference. I ended up selling my F75 in 2013 for this sole reason.

Fast forward to the fall of 2014. I am contacted by the good folks at Fisher wanting to know if I am interested in trying out a new version of the F75 they are preparing for market. I of course say sure as I am always game to go metal detecting with different units. A new F75 is sent my way along with a list of the possible improvements. One immediately gets my attention – improved resistance to electrical interference.

All the focus was on a new mode or “process”, as Fisher likes to call them. The new FA process is intended to better pull non-ferrous items out of trashy or mineralized ground. It does indeed work as advertised as I found out in an accidental situation I came across.

I went to a local park and did a simple hunt for non-ferrous targets, comparing the DE default mode to the new FA fast mode. I did not really care what I found as long as it was non-ferrous. I should note the ground here is very difficult, reading 1 on the Fe meter, the second highest reading you can obtain. Hunting in this park is very much like nugget detecting, and the best detectors get very limited depth and highly inaccurate target numbers as a result of the high mineralization.

One spot really summed it all up for me. I found three targets I could cover in a single wide swing that all read as ferrous in DE mode, but when I switched to FA mode all three switched to non-ferrous. FA mode is very fast with short, machine gun type reports in the audio. I was running in two tone mode, with ferrous giving low tones and non-ferrous high tones. In DE mode I could sweep and get three low tones in a row. Simply switch to FA mode and now there were three high tone reports in a row. This was an extremely dramatic result seen in person. In this case all three targets proved to be nothing more than aluminum targets, but they could just as well have been small hammered coins in the UK or small gold nuggets in Alaska.

I hate to oversell things and I have to note that the difference in going to FA mode is not going to be earth shaking. Most targets read the same in DE and FA modes. But FA provides a tipping point, a little push that takes targets previously ignored and lights them up. By shortening the audio response on targets it also attenuates responses to a degree and so depth and signals on the tiniest targets may be impacted. Depth however is not useful if a target is misidentified or ignored completely due to target masking from nearby objects. FA mode is another tool in the toolbox that can help produce targets in specific situations previously overlooked by others.

The new F75 also expands on the available audio options in ways many people will appreciate. These additions and the new FA mode will tend to get all the attention, but for me they pale in comparison to the new ability of the F75 to engage and disengage the new Digital Shielding Technology (DST). The version of the F75 I received had DST engaged at all times, and the difference in my ability to use the F75 at my home was as dramatic as it gets. My previous F75 was basically non-functional. My new F75 ran just fine, with only minimal EMI discernible at higher gain levels.

I noted no downside to this. Given the situation, how could there be? Other field testers however were concerned that in low EMI situations perhaps there was an edge lost by having DST engaged, and so Fisher decided to add the ability to engage or disengage the feature as desired. It does not get any better than that. Use it if you need it; leave it off if you do not.

All I know is this. What difference is there between a detector you can use and one you cannot use? All the difference in the world, and in my opinion I struck gold a second time with the F75 seeing it run with the new Digital Shielding Technology. That one feature alone means I can use the F75 in urban areas where I could not use it before, and vastly improves the reasons for my owning the detector once again. I am very confident a great many people will agree with me when they get a chance to try out the new, improved F75. Everything else in my opinion is just icing on the cake.
 

[Rick K - First Member]

As you pointed out, and as Keith Southern points out in a video he just posted, the FA mode is very useful for hunting small gold. Running the new F 75 in discrimination mode with the FA, it may be possible to get a much cleaner discrimination ferrous versus nonferrous reading on small gold than the F 75 has been capable of before.

I hope to have my hands on one by early next week and if I'm very lucky also one of the 10 inch elliptical DD coils for it. I look forward to playing with it and comparing it to my Gold bug Pro, my Deus and my Gold bug 2.

[Steve Herschbach]

Videos of new F75 by Keith Southern.

Digital Shielding Technology (DST) and Fast Audio (FA) mode:

New tone options:

[Steve Herschbach]

The new Owners Manual is now available for download

[Rick K - First Member]

The upgrade program for owners of all previous F-75’s is also up. It's on their "hobby" section page.

http://www.fisherlab.com/hobby/registration.php

Click on the upgrade button, the registration stuff is for new owners.

[Steve Herschbach]

Hopefully I will be seeing a final version F75 LTD2 this week because the moment it arrives I am heading out to an 1800's ghost town with it. I have yet to find that first gold coin and am thinking the new F75 can help me knock that find off the bucket list!

 

Here are a couple more pictures of that "Ugly Nugget".