Bench testing metal detectors using air tests is good for some things, but not for others: Air tests can provide a good idea of a shallow target's response - deep targets, targets in close proximity to other metallic items, targets that have been in the ground for a long time and extreme soil conditions can produce very different responses Air tests are not a reliable indicator of a detector's depth capabilities Air tests can provide a good method for comparing different detectors regarding their response to the same target Air tests indicate that, for some targets, the orientation of the target can be as important as its composition Air tests teach you that, in the end, it is probably best to dig everything within whatever you consider to be reasonable limits NOTE: It is entirely possible that you may not get the same results as presented here. The environment, manufacturing variability, the coil used, testing methodology and many other factors can cause different test results. * These files may be non-commercially distributed in an unaltered state.

US Coins This Excel spreadsheet is the result of air tests utilizing various US Coins. I tested the coins with three detectors: Minelab E-Trac, Minelab Explorer SE and Whites DFX. The coins were tested flat and on edge. The E-Trac seems to show the greatest difference regarding the two orientations. For the on edge tests the coins were perpendicular to the sweep direction of the coil. All three machines gave jumpy signals when the coins were on edge and parallel to the sweep direction of the coil. If you have Excel 2007 you only need to download files 1 and 2. Earlier versions of Excel will work, but the charts may not display correctly. If you do not have Excel 2007, download files 2 through 7. 1 - TBGO_US_Coins_ID.xls - Excel 2007 Spreadsheet      (corrected mislabeled coin - 3/19/09) 2 - TBGO_US_Coins_ID.jpg - Image of Targets 3 - TBGO_US_Coins_ID_XLS.jpg - Image of Table 4 - TBGO_US_Coins_E-Trac_Chart_Flat.jpg - Image of E-Trac Chart (Flat) 5 - TBGO_US_Coins_E-Trac_Chart_Edge.jpg - Image of E-Trac Chart (Edge) 6 - TBGO_US_Coins_SE_Chart.jpg - Image of SE Chart 7 - TBGO_US_Coins_DFX_Chart.jpg - Image of DFX Chart

Gold Jewelry This Excel spreadsheet is the result of air tests utilizing various Gold Jewelry items. I tested the jewelry with three detectors: Minelab E-Trac, Minelab Explorer SE and Whites DFX. The pieces were held flat in respect to the bottom of the coil. The readings will, in general, vary to some degree depending on the orientation of the target. The panda coin ring, for instance, gives widely different responses depending on whether the band or the coin is held parallel to the coil. If you have Excel 2007 you only need to download files 1 and 2. Earlier versions of Excel will work, but the charts may not display correctly. If you do not have Excel 2007, download files 2 through 6. 1 - TBGO_Gold_Jewelry_ID.xls - Excel 2007 Spreadsheet 2 - TBGO_Gold_Jewelry_ID.jpg - Image of Targets 3 - TBGO_Gold_Jewelry_ID_XLS.jpg - Image of Table 4 - TBGO_Gold_Jewelry_E-Trac_Chart.jpg - Image of E-Trac Chart 5 - TBGO_Gold_Jewelry_SE_Chart.jpg - Image of SE Chart 6 - TBGO_Gold_Jewelry_DFX_Chart.jpg - Image of DFX Chart

Silver Jewelry This Excel spreadsheet is the result of air tests utilizing various Silver Jewelry items. I tested the jewelry with three detectors: Minelab E-Trac, Minelab Explorer SE and Whites DFX. The pieces were held flat in respect to the bottom of the coil. The readings will, in general, vary to some degree depending on the orientation of the target. If you have Excel 2007 you only need to download files 1 and 2. Earlier versions of Excel will work, but the charts may not display correctly. If you do not have Excel 2007, download files 2 through 6. 1 - TBGO_Silver_Jewelry_ID.xls - Excel 2007 Spreadsheet 2 - TBGO_Silver_Jewelry_ID.jpg - Image of Targets 3 - TBGO_Silver_Jewelry_ID_XLS.jpg - Image of Table 4 - TBGO_Silver_Jewelry_E-Trac_Chart.jpg - Image of E-Trac Chart 5 - TBGO_Silver_Jewelry_SE_Chart.jpg - Image of SE Chart 6 - TBGO_Silver_Jewelry_DFX_Chart.jpg - Image of DFX Chart

DFX VDI Normalization This Excel spreadsheet was done to understand the different frequencies utilized by the DFX and the effect of VDI Normalization. You can read about it here . TBGO_DFX_VDI_ID.xls TBGO_DFX_VDI_ID.jpg