J. I used the all-metal mode on each of the models. (would that be the same as your Pattern One with no notching?) I only used one X-70, but used two different X-30's and two different X-50's. (although I didn't find any difference in ID readings, I did recognize a noticable difference in depth of detection between the two X-30ss) In the ID chart, you will see that the X-50 did indicate a "9" for some nickels. (in fact most of my old nickels register 9 instead of 12) Apparently it was the high side of "9" as the X-70 registered it as a "10" instead of an "8". These ID numbers were recorded using the stock 7.5 kHz coil on each machine. And, I even swapped the coils around between the control housings, just to see if the numbers remained consistent. They did. However, I did notice that when I would use the higher frequency 18.75 kHz coil, the numbers were different.
In a post I made last December as to comparing the two coil options available with the X-50, half dollars read 45 on the stock 7.5 Khz coil, but read 42 on the higher freq 18.75 coil. Quarters read 42 on the stock coil and 39 on the higher freq coil. Clad dimes read 36 on the stock coil and 33 on the higher coil. Oddly enough, nickels and zincs are the same on each. Round tabs read 15 on each coil. Small square tabs read 27 on each coil. But, as I increased the depth, the numbers became jumpy and fluxuated from 24- 27. Larger square tabs read 24 on both coils. Screw caps read anywhere from 18 - 27 on the high freq coil and those tested read solidly as 27 on the stock coil. An old 2 cent piece read 33 on the stock coil and 30 on the higher coil. Several IH cents that read a consistent 27 on the higher freq coil gave readings of 27 and 30 on the stock coil. Silver dimes read one of 30, 33 or 36 on the higher freq coil (depending on the specific dime). But were each one notch higher on the stock coil with readings of 33, 36 and 39. A large men's gold ring read 18 on both coils. Depth between the two was similar at 12 - 13 inches of air. A very small lady's gold ring read 15 on both and the higher freq coil did have a slight edge in depth of detection.
What do I make of all this???? It seems to me that, once you get target numeric readings of 30 or more, the stock coil will provide a reading "one notch higher" than the higher frequency coil. In other words, 45 on the stock coil became 42 on the higher freq coil. 42 became 39. 36 became 33. But, once you got to 30 and below, they were pretty consistent with each other.
The coin depth "edge" goes to the 7.5 coil. I attribute this to the fact that I must lower the sensitivity setting when using the higher freq. coil due to falsing. Without exception, the stock coil achieved approx. 20% more depth with each coin target. More with dimes. But, less with jewelry. Sensitivity to small gold jewelry gave an edge to the higher frequency. Not the big rings, but the smaller ones for sure. And, the higher frequency should be more sensitive to smaller targets.
Although I have not noticed my nickels "chirping" as yours might be doing, I have noticed that nickels don't detect as deeply as I would have expected. It is a killer for copper and silver. But nickels don't seem to be detected at a proportional depth. Kind of opposite from a C, V or T that I have used in the past. They were killers on nickels. But too fast of a sweep could sure pass up those little copper and silver coins. Even though there may not be any metal in the ground where you were doing the testing, I wonder if the mineralization has an effect on detecting an object with the conductivity of a nickel? Interesting point to ponder. Maybe one of the experts can help us out here?????
HH Randy
