Help-Pinpoint signal peak using White's 12 " coil?

[w4uvvjw]

Today I revisited a schoolyard where approximately 10 years ago using my Spectrum XLT I found a few common coins (i.e., pennies, nickel, dime) I was curious to see how the V3i performed. It did fine. The few coins found today based on their deteriorated condition and dating to the mid-1980s probably were missed when I used my Spectrum XLT. I noticed when pinpointing a valid VDI target I had difficulty sight checking a reference point for the "Super 12/300" concentric coil's center signal peak. Although eventually I found the target coin by digging a slightly wider perimeter hole I was never quite sure of a signal peak location reference point on the coil. As best I could estimate sight checking it was at the 12 o clock position interface of the smaller inter coil and the bottom of the "12" and "White's Electronics" identification sticker id on the short molded section that connects to the larger outer coil. Changing pinpoint peaking locations gave the same results. Although not necessary, it would be nice to know information for a starting point of where to begin digging a "plug" around the VDI's target center location. Is where I looked the "best of the best" target signal peak reference point or is it somewhere else on the coil? Tnx.

Program: Slightly modified coin and jewelry.
Mode: Discrimination with selected VDIs and selected VDI tone audio
Sensitivity: Average 2-4
Discrimination Setting: 75
Coil Size: White's Super 12 (Expert menu option: 12/300)
Area of country: central Va.
Type of site: schoolyard with outside tables, swings, monkey bars, etc. filled with "pea gravel" and large outside ground area
Type of soil: Thin layer of topsoil with mostly clay support soil
Sensitivity probe settings: varied
Ground probe setting: varied
Ground filter: 5 mhz. bandpass
Transmitter boost: off
Search display: Spectragraph
Analysis display: Sizing

 

[burlbark]

Practice pinpointing with a plastic bucket turned upside down and place a dime on it. You are going to have some slight difficulty pinpointing with the super 12" because it sees so many targets at once and the v3i will lock onto all the signals making you have to analyze in 3 frequency to match your vdi with suspected target type, then centering the coil.

Like with zinc pennies they hit on the 7.5 frequency and will have that 45-58 vdi depending on the state of decomposition. It takes a little more brain power using the bigger coil. If you have iron around it you will watch the 22.5 frequency jump around or the 2.5 for higher conductive steels or silver. It just takes more practice and walk around the target while in search mode and pinpoint.

 

[Larry (IL)]

Do you have VCO turned on, if not, do so and your problems will be solved, the VCO pinpoint should get you to within 1/2 inch dead center. On shallow targets you can either lift your coil up a little or you have ratchet pin point to reduce the target footprint. (squeeze the trigger a couple of times)

 

[w4uvvjw]

Tnx for the reply. I've tried trying to find a peak point using a single coin on the ground with inconclusive results. I will try it again using a plastic bucket. You are correct about the many signals being processed at once. I guess I will have to get used to digging a wider hole when using the 12 inch coil.

 

[w4uvvjw]

Tnx. I do have VCO turned on and when pinpointed for maximum depth I try to quickly sight check the coil to see if there is a corresponding recurring reference point. So far the best I can relate to is the upper portion of the small coil area. I don't think it is the center of the smaller coil. This location give me a good starting point of where to dig although I find myself digging a wider hole than I otherwise would expect to dig. That's a minor inconvenience as eventually I am successful most of the time. My portable coin "sniffer" also saved me some time today sifting through dug dirt piles and beeping when near the target coin. Soil in my area tends to be acidic probably in part due to the large number of pine trees.