Pinpoint question on the F5.

[Mick in Dubbo]

I've noticed that several folk have commented that the F5 gives an overload signal on just about anything that is just under the surface. My question is, if you simply raised the coil an inch or 2, wouldn't that eliminate the overload signal?
Thanks.
Mick Evans.

 

[Mike Hillis]

Hi Mick,

The F5 has no built in governor like many detectors do. The F5 is a hot detector. It can prospect gold and hunt chains. That heat coupled with the coil design makes a sensitive detector. However I have less overloading with the F5 and the stock coil than I do with my Tesoro Golden with a 4" coil.

Raising the coil a inch or two is all that is needed to resolve the overload and get a normal response.

Remember that the overload audio is a feature. It is designed to let you know when the machine's electronics are saturated by a large signal and has ceased working. If it stayed quiet you'd never know. The gain and threshold settings also play a part in how much overloading you will have as the higher gain settings will greatly increase the size of the target signal. If you live where soil mineral strength is low and allows you to crank the gain and thresholds on the F5 you will experience more overloading on some shallow targets. A price paid for power. But again, simply lifting the coil a inch or two resolves the overload condition.

Cal Cobra reported that his unit had a problem with overloading that wouldn't quit even when raising the coil. I do not know if he has returned his machine for service to fix the problem.

Good luck.

Mike

 

[Mick in Dubbo]

Thanks Mike.
It sounds like a great little unit. The local dealer has only just got them in yesterday. He hasn't figured out the price yet. Bit hard with the dollar all over the shop. They must be popular, because he kept ordering but couldn't get any.
Mick Evans.

 

[Cal_Cobra]

Mick in my case lifting the coil does NOT resolve the overload issue, it just stays kind of blanked out until it hits another "good" target.

I haven't had the F5 out in a while, but I suspect that I might be able to resolve this issue by ground balancing a different way (I've been using the phase/fast grab to GB).

HH,
Brian

 

[Mick in Dubbo]

n/t

 

[marcomo]

Apparently I have the same issue as Cal Cobra.

When my F5 goes into overload it will stop when I raise the coil, but it doesn't give me a reading when I raise the coil. It stays blank until I hit another target.

I'm kind of hesitant to send it in for service because it's not that big a deal and I don't want them to do anything that might reduce the excellent sensitivity of this machine.

 

[Mick in Dubbo]

Thanks marcomo. It's good to know of any little glitches that might come up.
Mick Evans.

 

[Cal_Cobra]

Apparently I have the same issue as Cal Cobra.

When my F5 goes into overload it will stop when I raise the coil, but it doesn't give me a reading when I raise the coil. It stays blank until I hit another target.

I'm kind of hesitant to send it in for service because it's not that big a deal and I don't want them to do anything that might reduce the excellent sensitivity of this machine.

Interesting to see someone else encounter this issue. I agree for the most part it's not a problem, EXCEPT for a really trashy area it will drive you nuts.

I've debated whether or not to send it in to Fisher to fix, but because the machine runs so nice and stable (even with the sens/thresh cranked) that aside from this snafu, I've decided to leave it alone.

 

[marcomo]

I agree with you, Cal. With no targets underneath, my Fe3O4 usually reads two bars so my soil is fairly mild and I'm able to run the settings high.

Mike Hillis had a good post about that where he detemined through his testing you could get essentially optimum performance from either 90 gain and 0 threshold, or 50 gain and +5 threshold.

The funny thing is occasionally when I lift and swing the coil after an overload, I'll get a flash of a readout and then back to blanking out.

 

[Cal_Cobra]

The places I've been hunting have pretty tame ground, and I was able to run the gain at 90+ and crank the threshold to almost max as well.

I do wonder if doing a manual GB would solve the shallow small target overload issue, perhaps some positive or negative GB would desensitize it a bit, BUT you might loose some depth or have to crank down the gain/threshold for stability....dunno, I need to mess around with it.

 

[upstatedetector]

I am an F5 beginner in every sense of the word but have noticed this in some overload issues: If you have discrimination turned up so that items are notched out, or if you have manually notched out said items, overload will occur on those items when they are large and right near the surface. I think the reason some people are then noticing that raising the coil away from the ground does not reset the ID is because the detector is then able to discriminate that item.

I overloaded last night on a piece of iron just under the surface. I then raised the coil 2 inches and did not receive a signal and my detector stayed in the "blanked out" overload screen. Annoyed I turned my disc way down and ran the coil about 4 inches over the target. Sure enough I got the heavy grunt of a low FE target.

I am mostly hunting in some pretty erratic ground right now and have not gotten ground balancing down either. If the above explanation makes sense to anyone who actually knows what they are doing, let me know.

Thanks & HH

 

[Cal_Cobra]

^ That's an interesting observation. In my case, I almost always use zero disc, I like to hear everything. The only exception is at some trashy parks I'll knock out foil, but the overload is on tabs, coins, and other small targets on or near the surface. It's not that big of a deal, but it would be nice if there was some option to disable it