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Some comments on the F75 as a prospecting detector

Have you ever tried the Teknetics T2 for gold Steve. I just got a good deal on a nearly new one, but can't find much information on the web about using it for prospecting.. I hope the F75 users on the forum don't mined me asking this here. I believe from what I have read that the F75 is a great machine, the fellow I bought mine from went to the F75.I just couldn't afford a F75 . Seb
 
Hi Seb,

No, I have not. But the two machines are so close in performance I'd have to think the T2 would do very well.

Steve Herschbach
 
heres a few found with the f75 stock coil in az :detecting:
[attachment 137572 MVC-588F.JPG]
 
Can you tell me what the range of VDI numbers would be for small nuggets? I live about 20 minutes from Coloma, the CA gold discovery site, and would like to try nugget hunting. Also have you tried the 5" DD coil for nugget hunting yet?

Thanks!
 
Hi,

Nope, I've not tried the 5" DD.

Here is scary info - small gold nugget VDI numbers can run well down into the small iron range. The only way to get all those little guys is to use all metal.

Steve Herschbach
 
Hi,

Wow, you are way out-smarting me! I'm a pretty simple guy when it comes to this stuff.

There is no way I ever expected the F75 to hit smaller gold than my Gold Bug 2. Never was the point; if you want small gold get a Gold Bug 2. I have one myself and in no way does the F75 compare when it comes to hitting the tiny stuff. All I'm trying to do is see how well the F75 does for gold as a multi-purpose detector. Obviously the Gold Bug 2 is a machine designed for a single purpose - finding gold nuggets.

There were no "test nuggets". We just used the detector in the field. I generally do not use discrimination as it causes too much gold to be lost, so I can't comment on the discrimination aspect at this point. The F75 correlates more with the White's MXT and Tesoro Lobo or X-Terra 705 as a gold unit and offers similar performance. It does not hit gold as small as the Gold Bug 2 but does get better depth on larger gold as would be expected of a machine running at a lower frequency. The hot rocks at my particular location gave a soft response as compared to a sharper response from non-ferrous targets and so could be discerned on that basis alone.

I am not trying to sell anyone on the F75 as a nugget detector. As I noted, other machines can serve that purpose as well for less money. I am more interested in seeing how the F75 does just to provide more information for those that do own the machine. The bottom line is that if all I wanted was a nugget detector I would not get an F75. It has too many extraneous functions and costs more than other units with comparable performance. All I'm doing is pointing out that the F75, if you own one, is a reasonably capable nugget detector. I've got one, and I'm using it to go find a few nuggets. If it was all I owned I'd do pretty well with it finding gold.

Steve Herschbach
 
Steve thanks for the explanation. I understand that you are presenting information on F-75 based on its own merit as opposed to comparisons with other units. I imagine there are quite a number of users that are very pleased to see anything and everything you might be able to put forward here. There has been very little said on the forums about this machine with respect to prospecting for gold.

Now as to comparisons, I
 
Hi Snowman,

Well, like you said, it is the physics we are dealing with. I do not think it matters what detector you use, At the tiny end of the scale gold and iron signals can overlap, just like gold and wet salt sand signals overlap. If I am chasing really tiny stuff, like gold under a grain, I have to hunt in all metal. Any amount of disc simply eliminates the tiny gold.

Larger nuggets at the edge of detection depth often read as iron. I think it is simply because the non-ferrous signal is so weak and the ground signal overwhelms the disc filter into thinking it is a ferrous target. Standard practice with an MXT at Ganes Creek is to hunt in relic mode whereby a non-ferrous target gives a high tone and iron a low tone. The disc knob sets where this tone break occurs. If you got an iron sound, you'd always want to knock off some soil, as the signal every once in awhile will switch from ferrous to non-ferrous. If the reading remains ferrous, move on.

The problem with the Gold Bug 2 disc system is it silently rejects targets, and so if you hunt in disc you simply pass over a ferrous reading not knowing it was even there. So you should hunt all metal with the Bug, then flip to disc to check targets.

I am sure the F75 is no different. The implication here is for turf hunters. When prospecting knocking a couple inches off to check a target is no big deal. But how do you do that in a park? People simply rely on the detector to tell them what is down there, and in the case of coins at max depth people are often being told by their detector that it is a ferrous target. And so the coin never gets dug.

People tend to fault detectors that sometimes have you digging a deep nail. I not sure that is a bad thing. I don't think I'd trust a detector that had 100% ferrous rejection. I think it is about how you bias the system. You can get all the gold and dig a bit of ferrous stuff. Or never dig ferrous, but miss gold. Or coins.

The CZ units had a reputation for calling deep iron non-ferrous. But maybe the CZ units are also less likely to call a deep coin ferrous?

I rarely employ discrimination these days unless hunting sports fields, where I will notch out iron and high coins and go after the ring range. Most of my time goes into hunting beaches, tot lots, and prospecting, all places where I tend to dig everything. I have a gold pan in my garage half full of good finds. And a trash can next to it full of aluminum and misc steel trash galore. I'm somewhat amazed at the amount of junk I dig and yet I'm still having fun. The F75 is static all metal is truly remarkable, giving my PI units a run for the money.

Steve Herschbach
 
Very well stated Steve, I see things pretty much the same. BTW, I do own and use an MXT for mineral searching, but have not used it for gold hunting yet.

The nice thing about MXT, as you point out, is that there are choices as to how one elects to use discrimination. In the relic mode, trigger in the center position, you decide just how much iron discrimination to dial-in for the tone change, and deal with each individual signal with further investigation or not, depending on your frame of mind, weather, or bugs at any given moment. But at least you are aware of the signal and make a conscious choice. Or check out each signal using the prospecting mode.

Where repetitious iron debris or hot rock signals that by sheer numbers are a source of irritation, one might elect to run in C&J or Relic (trigger forward with disc dialed-in) with a sufficient iron discrimination level to break-up/eliminate such signals to save your sanity. You accept that some small gold will be lost, but at least its an alternative to giving-up and walking away. This is a benefit of having a full discrimination circuit as opposed to only tones/visual ID. Moore Creek basaltic hot rocks might be a good example where an audio disc circuit would be preferable to say, the prospecting mode's iron audio ID feature grunting away and driving you crazy.

Its handy to have that versatility utilizing iron discrimination. By comparison to MXT, the F-75 does not allow one to define the tone change by arbitrarily setting the discrimination level. Its iron tone represents the full iron scale, similar to MXT in relic mode with trigger forward and disc set to zero. However, the F-75 does allow one to utilize the iron tone in conjunction with an arbitrary iron discrimination setting dialed-in. For example, one can elect to set discrimination at a setting of "3" in JE mode as a means of quieting spurious ground noise, but also have iron tone (2F) activated. All iron signals ranging from "4" up to and including "15" will be heard as an iron tone, but you also benefit by reducing (discriminating) ground noise that can result where the F-75 in zero discrimination may see the ground to some degree as a "target". This unit can use all the help it can get in dealing with various noise sources, and this is a good example of where using this iron disc/tone configuration also aids with overall stable detector performance. Of course as you say, the use of iron tones is really only practical in situations where material can be removed easily. Otherwise, for instance with coinhunting, one faces potential masking of desirable non-ferrous targets, either because of depth in conjunction with magnetic ground minerals, co-located ferrous/non-ferrous targets, or due to the effect of disturbed ground.

MXT and F-75 are similarly both deepseeking capable (aside from their all-metal modes) utilizing small iron discrimination mode settings over disturbed ground (loose "stirred-up" mine tailings for example) compared to some detectors that perform poorly over such ground using any amount of iron discrimination, for whatever reasons. JE is the only F-75 discrimination mode that will allow utilizing effective small iron discrimination while retaining deepseeking capability over disturbed ground and yet still sensitive to small nuggets of a few grains. The other disc modes must be used in "zero" discrimination to achieve similar depth performance over this type of ground.

The stat all-metal mode is really something if you can make good use of it. Over my ground, unfortunately, the sensitivity has to be reduced down to at least the "60" range or less in order maintain a half-ways practically useful ground balance and reasonably stable threshold as the coil is swept over even slightly changing ground. I find I have to be circumspect as to how far above the ground I manually retune the unit even at the "60" sens setting to ensure the unit remains practically operative. The stat mode is so sensitive to ground minerals, but is also extraordinary in depth capability. But as I noted, due to the much-reduced sens setting, I
 
Hi,

Now that was one information packed post! You've obviously put in a lot of time with the F75 to learn the finer points. Thanks for sharing. I'll put the tips to use this weekend.

Funny you mentioned the MXT in coin mode with trigger forward. That is exactly how I had to run the unit at Ganes Creek and for exactly the stated reason - to preserve my sanity.

These forums are set up by brand or model. I may have to go set up a "Dave Johnson" forum. Units like the Gold Bug, Gold Bug 2, Lobo ST, GMT, MXT, X5, and F75 to name a few are more alike than different and it is fun to consider the finers points of each. Each has nuances that might make any one of the units better in a particular circumstance. I get amused when people get up in arms over this versus that unit. At the end of the day I can grab any of them and go find gold.

I'll make note of the sensitivity setting on the F75 next time I play with it in static mode. I was actually using in in pea gravel at a playground digging everything that went beep. The pea gravel is magnetic in that my super magnet picks up gobs of it. Most detectors get little penetration in it and so I enjoy running my PI units or units with a powerful all metal like the F75 in the stuff finding all the things the discrimination people leave behind. I believe I was running sens at about 80 and did have to run it a bit off the ground but it was pretty stable. And like I noted on par with a PI unit for depth.

My problem is that I run PI or all metal so much that when I try out a discrimination mode the loss of depth is alarming. I literally feel handicapped. Like in these pea gravel locations. Turn on the disc, and there are almost no targets. You'd walk away thinking the place was hunted out. Fire up a PI or go all metal and the place comes alive. And the digging is so easy I simply don't mind digging ten or more junk items for every so-called good item.

Another unit that has a dynamite all metal mode is the X-Terra 70/705. The disc mode seems quite lack-luster to me. Go to all metal prospect mode and wow!

Steve Herschbach
 
Steve,

Thank you for bringing up the subject of magnetic pea gravels! I have this stuff in spades, particularly in streams & rivers that naturally classify it out by current action. Unless one has had the fortune(mis-fortune) of dealing with it, it can be difficult to understand the steps(settings) needed to counteract it's effects. You are one of the few people I've ever seen even mention it, and so I can relate completely to what you are dealing with. I also have piles of stones that I refer to as cobbles that have the same qualities, and likewise any low conductors report as iron within a few inches and after that high conductors become unstable and then report as iron in the 5 to 6 inch range. Trying to achieve a reliable GB is a nightmare as there really is no GB, there's hundreds of them each with their own little GB point. Hunting for small gold jewelry in some of these conditions is riding on the bloody edge.:stars:

Thanks for bringing up the subject!

HH
BarnacleBill
 
Steve and others - many thanks for taking your time to post on the F75 for nugget hunting. I have been wondering after my trip to Ruby, AK if the F75 could handle Moore Creek. Now it seems I should get the funds together for next summer as I could now have a choice of both camps! I am going to take my time and reread the above comments. Seems now it is time to get out in my hot rock pile and practice. I do think hot rock masking may be an issue. I am going to practice with a tape over the meter so I am not initially put off by low iron readings. And I also notice hot rocks signals may not be as "centered" as the nuggets. Also, if it is a help, I've noticed the nugget readings seem to jump around from low to higher, whereas iron, unless bent, usually just gives a solid one on one reading. It seems the word is now getting out on the F75. SRLance in Santa Rosa Ca.
 
Hi,

I think the F75 will do about as well as a VLF unit can do at Moore Creek. And you whacked the old nail squarely on the head - masking!

There are various schemes that can be employed at Moore Creek to get VLF units to shut up on the hot rocks. The problem is that all of them involve getting the units to ignore the rocks. And that means anything under or next to the rocks is going to be ignored also.

I did about as well with a Gold Bug 2 and 6" coil at Moore Creek as I've done with any unit. I think the smaller coil could see between the hot rocks better. The F75 with its DD coil and superb recovery time should do as well and get better ground coverage, which is a big part of the game. I should have put more time in with it. But at the end of the day it is not a PI unit, and that is what you really want at Moore Creek. Where a person might score with the F75 is in the old campsite a mile downstream. There is gold in there but all the PI guys tend to stay away due to all the iron and steel trash.

The first week at Moore Creek for next summer just sold out. The new owners are thinking of reducing the price and aiming more at the GPAA highbanker crowd than the detector people. Which would mean no more bulldozing. So if you are serious about giving it a go I'd get into the second week. Even if there was no bulldozing that week there will still be plenty of finds for at least awhile until all the ground gets thoroughly covered.

Steve Herschbach
 
Hi Bill,

I love the pea gravel. Lots of people detect the stuff but most are only skimming the surface so it leaves me lots to dig.

The problem is our idiotic school district is slowly replacing the stuff with fake wood chips! I went to one of my favorite schools recently and the pea gravel was gone. I hate the fake chips since you pretty much get in air depth in the stuff and so my advantage over the disc crowd diminishes. I still make finds in the stuff but it is just not as much fun.

I feel sorry for kids these days. Would not want little Timmy to fall down and skin his knees, would we? I darn near killed myself on the monkey bars when I was a kid, but the last thing my parents would have thought of would be to sue the school district. I basically got told how stupid I was and little Stevie learned to hang on better next time.

Your cobbles sound like the same kind of mixed blessing. Really hard to hunt, but therefore all the more likely to be hiding some good finds for a determined detectorist like yourself.

Steve Herschbach
 
Steve you are more than welcome to anything that can be forwarded along. Its very little recompense for the wealth of information you
 
Hi Jim,

Ha! This is funny. I thought it was you and did some searches on SNOWMAN. to see if it might be. I only found three posts on Find's and so figured you recently signed up in response to my post. say F75 and prospecting and it is like dropping bait in the water!

I thank you for the kind comments.

I have a confession to make Jim. You obviously have a stronger analytical bent than I when it comes to detecting. I usually grab a machine, find some basic settings that work, and go detecting. I rarely can swear that my detector is tuned to perfection. I actually do not even pay much attention to it, just like the static all metal mode thing. I can't swear to where I had it set. I just played around a few minutes, found something that seemed to work, and went with it. I guess I do well going by what people who have hunted with me say. But I attribute it more to having a feeling for for where to put my coil.

I tend to focus more on having the unit that is inherently better at what it is that I am attempting than to be perfectly tuned at any given time. I'm a firm believer that it is basically about hours. Most detectors stay in closets or garages, and they don't find much there. I think the real secret is finding good places to hunt, being halfway proficient with your detector, and then putting in the hours. And then having a sense of whether to go left or right. I do not know why, but more often than not I seem to know which way to go.

I've tried to be logical and set up search patterns. But I have always done best by just wandering around following my nose. Search patterns require logical thinking. Grid the area out. I'm at my best when I just let it go and wander around. Maybe I'm employing years of experience, or maybe it is a sixth sense. I truly do not know anymore. All I know is turn me loose with a detector with a couple other people and nine times out of ten I will get over good targets more often.

I saw this at Moore Creek in spades. 20% of the people are making 80% of the finds. A lot of it boils down to enjoying what you are doing. I enjoy detecting. I can detect for hours, dig junk, and consider it time well spent. Others are detecting to find stuff. Their brains are calculating dollars per hour. No finds in such and such a time is a waste of time and they are not happy. Their unhappiness messes with their detecting ability. They might actually give up the game. Others find detecting inherently boring and so force themselves to do it as they have read they must to find something. They are bored out of their skulls and paying absolutely no attention to what they are doing. "Sleep walking detectorists" I call them. If you see one it is apparent. They are still at it, but may as well have quit. The best hunters are as much in the game 12 hours or 30 hours later as in the first hour they were hunting. Good detectorists have lots of patience and long attention spans. And a sense of what is realistic.

So I salute you Jim. You are obviously very knowledgeable and I'll pay attention to what you have to post, along with a handful of other people. There is Bill Ladd and BarnacleBill and Digger and Jackpine Savage in no particular order and others not mentioned I pay attention to. I don't learn much these days reading posts, and so I really value people like you and them that can teach me a trick or two. Please keep posting.

Bill I have to give some crud for being a bit too brand loyal in the past but he has lightened up as of late. Brand loyalty is a limitation I cannot accept. All the major manufacturers make good units, and so I've had Compass, Fisher, Garrett, Minelab, Tesoro, Troy, and White's units. Right now I have a Fisher F75 and Gold Bug 2, Garrett Infinium, Minelab Excalibur II 800 and GPX-4500, and White's V3, GMT and TDI. Great units all and having a ball with all of them. If anyone thinks that is nuts I have to point out I do not have an RV or an ATV or a snowmobile or a good set of golf clubs or a safe full of good guns or a Harley and I could go on. Detecting is a cheap passion and one that can pay for itself and more. I can't imagine owning only one detector or limiting myself to one brand.

I guess I just proved I like to listen to myself yak, so time to turn in. Happy Hunting!

Steve Herschbach
 
Now, I don't go prospecting for gold as I'm in the UK, however small gold is my prime objective.

The gold I hunt is 2000 year old Celtic gold and the quarter stater unit is small but usually 22-24 carat, this one dug last Sunday weighs in at 1.51 grams, and gives a solid VDI of 30 on the F75 and was dug at 4".

quartstater5gfs.jpg


This is another of 1.53 grams, it's looks larger but it is just the image scale that differs.

quartstater3gfs.jpg


Of all the machines I've used over the years the F75 and the Troy X5 have proved to be the best yet, the Lobo ST wasn't really in the running.

It would be interesting to try a Goldbug on these sites, however they are stuffed full of small iron, coke and hot rocks.
 
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