PI?

[markg]

I was hunting Sunday afternoon in one of my old school yards where in years past they dumped the coal waste from the furnaces. This material attracts to a magnet and can cause weird problems for a metal detector especially after a soaking rain. Well anyway I was hunting the area with my (None Whites machine) The machine was very noisy with ticks and clicks and sporadic high tones. After a while I decided to switch to monotone (one tone) and started digging anything that even started to repeat. I came across a very loud signal and knew it was close to the surface, but the VDI numbers were everywhere but mostly in the iron range. Switching over to 4 tone and the audio sounded like pure trash and I can say for sure I would not have dug this target in any setting other than monotone (actually reminds me of the Tesoro Tejon one tone detector) I Also know from experience how some ground conditions and co-located iron objects can cause the VDI to be very bouncy. So I decided to recover this target and at 1

 

[steve herschbach]

I have never coal cinders or waste with a GPX 5000. It handles almost anything that you can throw at it due to the large number of "timings" designed to eliminate various ground conditions. However, a GPX is not a cheap date so a lot to spend just to find out unless you could find somebody with one to give it a try. The White's TDI with its adjustable pulse delay would be a much less expensive option. Regular non-ground balancing PI detectors would be iffier yet. I wish I had a better naswer for you. The main problem with a PI may be it may handle the coal but if there is any ferrous material in the mix you could end up going nuts on ferrous trash.