Disappearing targets

[cymro]

Hi my first post.
Forum is great. I have X70 hoping for some help with disappearing targets this has happened a couple of times. Example solid signal in all metal mode standard coil. Target steady on 40 from any direction. Start digging and the target disappears. Increase sensitivity; sweep from different directions no response. Changed to prospecting mode, target reacquired, in this case a silver based pre decimal coin. This coin was approximately 200mm deep in dry sand. Had ground balanced and noise cancelled, tracking off.

Thanks
Dave from Tassie

 

[BarnacleBill]

Not unusual with many detectors. Several factors can be at play depending on your soil type. First is that you disturb the target and turn it vertical making it a much weaker response. Second is the way motion detectors work. There is ground filtering involved in distinguishing a target from the background noise in Coin & Treasure mode. That's why that mode is so much quieter than the Prospecting mode. The Prospecting mode has much less ground filtering which is why you can hear the ground noise as you sweep the coil. You are also creating a hole which has a different ground balance point than the surrounding soil.

HH
BarnacleBill

 

[morelic55]

n/t

 

[willy]

What I noticed is that switching to the all-metal DISC. mode, not the prospecting mode, will allow the detector to reacquire the target. Also, another odd thing I noticed a while ago was that a pulltab suspended about1/2 cm above the ground (on edge) gave no response. Taking that same pulltab and lodging it in the ground (on edge) gave a great response. Putting it back on the piece of straw that was suspending it caused the signal to be lost. Note, however, that switching the detector to all-metal disc. allowed the detector to again signal on the pulltab. ...Willy.

 

[Boris]

I was also thinking that every now and then if you are discriminating out iron and happen to move an iron object to a close proximity of the target you may get masking. Is this possible?

 

[Jackpine Savage]

I don't use a pinpointer and have lost many targets in the dirt pile from the iron. When scanning the spoils you have to sweep the coil very slowly in order to not miss the good target. Gotta wonder how many have pushed the dirt back in the hole and moved on.

Tom