Any recommended settings for the F70 in Gold country, Northern California?

[vincentvangerven@gmail.com]

Have obtained a fisher f70 and it's stable when air testing, but when I put the coil to the ground in my heavily mineralized soil it's going haywire, very chatty.

Any users of this machine in my area who have some recommendations?

Another thing that I noticed is that with just about any setting I tried it will identify a small balled up gold necklace as iron, with a iron tone and number 7 on the screen.

I know small gold typically scores lower on the chart but i was a bit surprised since the detector was once marketed to even be usable for gold prospecting

Thanks

 

[Picketwire]

The threshold adjustment is your friend. If it is too chatty in disc, turn it down and it will quiet down. If in all metal, turn the sensitivity down until the threshold smooths out. It is not surprising that a small chain of any metal would ID as iron, even the smallest nuggets will too. Heavily mineralized soil necessitates lowering of sensitivity on high powered detectors.

 

[vincentvangerven@gmail.com]

Thanks for the input! I found quite a few useful posts online about this detector, which is helping me understand the unit a bit better. I tried the chain with a Tesoro Tejon and Conquistador and got the same result, being the detector ID-ing the chain as iron.

Thought the F70 might not do this since I see it advertised as a suitable candidate from prospecting, but I can't say it's doing anything different than the previously mentioned Tesoros.

Still having fun learning the F70

 

[jmaclen]

Thought the F70 might not do this since I see it advertised as a suitable candidate from prospecting,

Even the latest simultaneous multi frequency detectors will detect small gold chains very low on the target ID scale right around the ferrous/non ferrous tone break. As stated above by Picketwire, smaller low conductor targets like gold and lead that weigh less than 0.25 grams may be detected with non ferrous responses in air tests but they will likely have ferrous responses in magnetite mineralized ground unless they are really near the surface.

I do detector prospecting a one site here in Colorado where modern US clad coins used for testing there will have ferrous target IDs if buried deeper than 5" in that highly magnetite mineralized dirt even using the latest SMF detectors. An F70 is definitely going to call those coins as iron if it can even distinguish them from the ground itself at that site.

It's been a long time since I owned and F70 but I do keep records and it air tested a 0.25 gram gold nugget at 1.5" in all metal. I would expect it to do a little worse on a 0.25 gram target in higher mineralized ground. Part of that result is the F70's 13 kHz operating frequency. Detectors that can run at higher frequencies, 20 kHz and higher are more sensitive to smaller low conductor targets and may be able to hit smaller targets better in higher mineralization too. Detectors with the latest simultaneous multi frequency operation can be run hotter and more stable by comparison since they are very capable of running stable on hotter ground at higher sensitivity, so they are even more sensitive to really small low conductor targets.

Back in 2008 when the F70 was introduced, there were more near surface gold nugget targets that an F70 could hit easily than there are now at least where I detect.

The F70 with a smaller coil will be easier to ground balance and can run more stable on hotter ground. What coil are you using?

A 0.25 gram gold nugget is a decent sized picker where I detect and there aren't too many of them left near the surface here as well as anything bigger unless I get extremely lucky.