F-70 depth question

[stefpryce]

I have kind of a general question question for everyone... And a more specific one for anyone using an f-70.
What would you say is the average depth of coins you dig? And also how deep is the deepest coin you've dug?

I know soil mineralization and things like that can effect depth.... I've used my f-70 for a few months now and have yet to dig a coin at more than 5 inches. Pretty concerned a buried a silver quarter at about 7 or 8 inches and barely heard a thing...
Any setting suggestions, comments or advice would be greatly appreciated.
Thanks
SP

 

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[Lowbatts]

Well there is no average depth that I dig targets at. They go from surface to 8" with my F-70. Only hit one deeper than that this year, a wheatie at 10". My F-70 id's right on and hits good on all targets to 8" it seems, and they simply disappear after that.

I usually have it at:
disc 0
dE
sense 90+
thresh 0
notch 5

I've been working sidewalk work the last couple weeks and because the matrix changes rapidly I will adjust notch or thresh or sense to meet the noise levels I'm getting. The parkways were turned yesterday so we are hitting those and they are much kinder to the signal schemes, can just about crank it out using the 5" DD coil.

I deliberately went in search of deeper targets on a couple instances over the last week or so. Using At on Program 2 set comfortably strong I just listened for faint responses or those I'd suspect were out side of the shallow junk range using the 11" DD coil.

When I'd find a target I thought sounded faint, I'd hit ID mode in Program 1 and check again, sometimes an ID, sometimes not. But I still didn't get any real deep targets. In fact most turned out to be 3-4" smallies of junk. A few turned out to be mems down deep for some reason.

But overall, I'm a happy camper, got a 1877 seated dime a couple days ago in that trash mix under a slab. For me, the F-70 is NOT a deep machine, but it has some nice virtues about it that will reward you if you use it to it's advantages.

 

[stefpryce]

Thanks for the pointers lowbatts... I'll give those settings a try... Especially because I find myself in mostly trashy areas as well. I tend to stay away from At mode and use the Dp tone, but than again I haven't hit anythng deep... I also like your tactic of switching from p2 and checking signals in p1. I run a few different settings and keep you posted. Way to go on the seated, I've yet to get an opportunity to hit some torn out sidewalks. But it sounds like your a fan of the 5" coil? My plan is to save up my dug clad till I can pay for on that way.. Hahaha. I actually probably pretty close. All and all I do really like the machine.. But just Being new to mding and the f70 in general all tips help. I dug a liberty cap large cent at 2" at an old home site a few days ago, so If I can just keep having luck like that I won't have to worry about hittin anything deeper.. Hahaha.
But I really your appreciatenyour response.
Thanks
SP
hh

 

[Lowbatts]

No problem Stef.

Hit the parkways along those sidewalks today, got two silver turquoise rings and one white wedding band, one old "golden" tie tac, one 1903 IH, a small lapel pin that reads LIBERTY BOY SALESMAN around a figure of the statue of liberty, 2 wheaties and clad enough to go around the vendoteria at work for a day or two...

So coinage was mediocre but diversity of finds and the spread on the age of the finds was awesome. Almost all of it came up with the F-70 and the 5" DD coil. Second run with the CZ brought the third ring, the wedding band and one wheatie and most of the mems.

The two guys with me, one had an ETrac and one had a V3, both had excellent days also including more jewelry and a two-center and two silvers. I think all three of us would have agreed that any of the finds were recoverable by any one of us, it was a matter of who put the coil over the target and read the info their unit was supplying.

That might not be true on all occasions but today it seemed the case as the targets were generally within 6 inches of the surface.

Congrats on that LC!

I'd advise you test the 5"DD coil against a lot of trash to see how it reacts first. Seems to be some offset from the big coil on some tabs and beavertails that up-averages their read to the cent/dime level. But in a sidewalk tearout site, you're gonna want to dig EVERYTHING anyway!

 

[George (MN)]

I use my F70 at the factory presets DE threshold -5 sensitivity 60. At these settings in my ground, there aren't too many false signals but I can still get a dime down 5". My soil is very bad, if I turned the detector way up, I doubt I could tell good from bad.

My IDs often bounce between 2 or 3 categories at 4"-5". Deepest coin a copper memorial at just over 5". Zincs & coppers I've noticed if they have been in the ground very long will give a wide signal in pinpoint like I'd expect from a can (corrosion & the halo effect).

The problem here is my soil type varies & much of it is rocky. Get lots of iron signals & pops or clicks that I think are mostly hot rocks? If you have bad ground, the depths some others report with good ground will not be possible in your area.

You can confirm that your F70 is likely working properly by doing some air tests. If you can find some settings where you can get proper ID on a quarter at 10" then your ground is the problem. What happens at some depth the coin signal will become weaker than the ground signal, causing the detector to give jumpy wrong IDs or no detection. It's not your fault or the detector's fault, it's the ground & I have to keep telling myself that as I read the field tests.

A detectorist was over at the only pre-1963 park within 5 miles of me. I asked how he did & he said 3 silvers. I was shocked as I had only found 1 silver there in my life. I assumed it was because of his Explorer's superior depth, so I asked him how deep they were & he said 4". HH, George (MN)

 

[stefpryce]

Tha ms for in the input guys! I really appreciate it. I'm gonna get to work on some air test with fresh batts this week and also make it out to a few new sites and hopefully if the rewards keep coming I won't worry about anythng deeper. I contacte fisher with the question just to see if the have any pointers and just to rule put any sort of machine malfunction.
I'll keep you guys posted but again thanks for the setting advice and stories.
I appreciate it...
SP
hh

 

[Streak!]

if raw depth is an issue, you may want to try SL mode. Its deeper than De mode, but you wont get the separation DE will give you. you'll have to swing a tad slower.........but its great spots where clutter isnt a issue. High disc will affect depth too, although not as much on the f series machines as some others. If I want raw depth...............I'll use 0 disc................................... monotone (but prefer 2F) and SL mode. I've dug silver with the 70 at 10+ inches in certain areas. Itspossible that in your area you just dont have coin deep though. Is it pretty dry, with hard pan and rocky there? I find my deepest coins come from soft loamy spots.
We were out tonight and I was digging wheaties and mercs at a good 8-9 inches at an old school site that was being torn up, with decent IDs and good signals. soil moisture will often affect deph too........with better depth bing had with damper soil.
Its kind of hard to give you good advice without knowing more specifics about yourlocal conditions. if set up right, the 70 can get almost as much depth as my F75......but not as good as my LTD. I also should mention that I use the 11" DD on my 70 pretty much exclusively. Streak!

 

[Lowbatts]

Hey Streak,
Nice depth there!

What's your GB look like when you FG that rig?

I know ground mineralization isn't the whole ball of wax, but it's pretty close to it. I use disc 0 also, but notch out to 5, 15 or 20 to clear the chatter if it's under slabs like I've been doing lately. The cinder, iron, clay and gravel mix under the sidewalks can be brutal!

 

[Streak!]

Hey Streak,
Nice depth there!

What's your GB look like when you FG that rig?

I know ground mineralization isn't the whole ball of wax, but it's pretty close to it. I use disc 0 also, but notch out to 5, 15 or 20 to clear the chatter if it's under slabs like I've been doing lately. The cinder, iron, clay and gravel mix under the sidewalks can be brutal!

things usually Gb here (with all my Ft machines) right around 65-70. I usually show no Fe304 meter reading either (dirt bar on the 70).
your right...................ground mineralization is a REAl biggie when it comes to depth. If mineralization becomes a prob where I hunt.............then its all metal instead of disc. AM handles the mineralization much better. It will still affect the machine.........but not as bad as it will in disc! I also MUCH prefer the 11" coil on the 70........probably because thats what I have become accustomed to on both the 75 and LTD. its an awesome coil. I find that while upping the disc will make the 70 quieter....it also takes a little bit away from the signal quality. I have to out up with more noise with low disc..........................but get better sounding (diggible sounds) signals from deeper targets. you just have to use the 11" coil and go a bit slower. Have you been using the 5" DD for those sidewalk sites your doing? You can literally max this little coil................and its quiet and stable. It gets VERY VERY good separation..and should work good in that enviroment. you'll give up a bit of depth........................but the trade off will probably be worth it.

 

[Lowbatts]

Streak, you wouldn't dare bring that 11" coil into these sites. Tried it, no go. Nothing but noise.

Everything from noisy overhead lines to the hot rock cinder bed and degraded metal under the slabs and you have to be able to pick targets from among a bed of iron and hot rocks. But you surmise well, the 5" DD I have is unbelieveably hot on targets and depth even in those conditions. I've been wondering if my unit was tuned for the 5" DD instead of the 11" DD. I've been hitting goods down to 7" in the parkways at the site with the sniper coil and that's close to max id depth for the 11" DD.

Now my CZ's, all have/had much better id at greater depth, but I could not use the 5" coil on the CZ5 or CZ7 I had, just awful at id'ing.

The other issue is crosstalk, get it from the guys nearby using the the ETrac, V3 or as today a DFX. It's worse on the F70 than on the CZ and I can change the freq setting on mine but it has little or no effect. With the larger coil, it is much worse. Much more tolerable with the 5" DD.