kac

Nice haul. Did you use the cheaters to check the stones on the rings?

Depends on how well the frequencies are normalized to the audio and tid. SMF just evens the response to a range of target responses. As I had said before coils have a range where their set frequency will end and frequencies will start to drop down as the signal fades off. This shifts responses of those targets especially mid and lower conductors. Also keep in mind high frequencies are more responsive to lower conductors. Small bits of iron oxide may fall into the ground phase range on very low frequencies so the machine will be quieter. D2 does a very good job in a wide range of conditions but there are areas I can get falsing when in 40khz smf and will often use 14khz smf or mono so desirable targets are easier to hear. Alternatively you can slow your swing speed which helps in most cases.

Very cool. I have seen a couple for sale but they don't stay posted very long.

Very cool. Large cents do ring up high. Yours should really clean up nice with a lil spit and 60 grit sand paper you would thing you found it on the east coast 🙂 Any reason why They disbanded the s-shaft? Apex seems to spec out lighter than Vortex and balances very well.

One to ask is Carl....

Zinc is shiny when scratched. I think it could be an early spin cast item done in a rubber mold (silicone molds came out much later). If so it might be from a much smaller item than we know. Most rubber molds are 12" dia or 9" dia and rarely 18" so the item most likely is not a big serving platter or similar. The part looks like it has undercuts so it either had to be cast in a rubber or silicone mold or done with lost wax. Still interesting find giving the time the building was taken down.

Nickel would be a duller gray. My guess acid tests on plating wouldn't be accurate due to the nickel and copper base layers. Could be chrome plating? What color is the base metal when scraped? I still think it's zinc because pewter is very pliable and wouldn't crack like that nor corrode on edges as that shows.

Looks like silver plating. Copper then Nickel are used as base plating for gold, gold tone or silver especially on pot metals. Pewter holds up well, pre 1770's all pewter had lead and are typically dull gray. Britannia pewter (post 1770's) is lead free and contains antimony. Good chance the piece is a replica that was spin cast in a silicone mold. If so then maybe done in 70-80's?

It may not be pewter as pewter is difficult to plate and requires heavy copper first layer followed by nickel then silver. Also pewter shouldn't degrade like that as it is primarily tin that holds up well. Same reason bronze holds up well as it has tin in it. Piece could be zinc maybe? Very cool place to hunt.

Testing here has not shown any target phase angle shift with and without the carbon shaft on any of my machines in motion with, static and without. I have not been able to prove that carbon shaft would effect depth. IB coils have a range that operating at the frequency of the machine to a certain point. Some coils have further ranges, some less. There is also a range beyond that where the frequencies will drop off as the signal fades. This is true on single frequency machines, selectable and smf. They all behave the same. What this means is once you start going beyond the coils limits and frequency drops off the gamut of mid and lower conductors drop, ie a nickel will have a lower number as the signal fades. Fringe targets and weak targets like thin gold may even drop into the ground range where the machine will not even respond to them. Why you won't see a prospecting machine running < 5khz as they will be blind to targets in that range. This is also you may see deeper machines running in lower frequencies as they are less responsive to small deep targets making them quieter for deep searching. EMI and Ground mineralization will reduce the coils range. As I have told others people can use this fade of signal to help determine target type especially around aluminum trash as aluminum is unique where it has a sharp fall off due to low density of the metal while more desirable metals have a more gradual drop off. This is considered a round tone on analog machines but can be noticeable using the nose or heal of the coil and wiggling off the target. Back to carbon shafts. I haven't been able to prove or disprove if they effect the drop off on targets here. Maybe there is some conditions that can cause it but I am pretty confident in using them here.

I run my machines with gain as high as conditions allow and still never had the lower shaft cause the machine to respond. I do quite a bit of woods hunting and bumping around the undergrowth has never posed an issue. Some coils can be knock sensitive out of the box and should be replaced/returned. People may mistake a knock sensitive coil and blame the carbon shaft.

The lower shaft doesn't sound off when it isn't moving. My test was to see if there was enough carbon to effect the coils base specs which it doesn't.. Example on the Gold Racer at 56khz Carbon shaft alone produces an ID 37 Carbon shaft with a nickel attached to it 57 Nickel alone 57 Carbon shaft layed on the coil (not in motion) and nickel passed over 57 Carbon sharft was passed over the coil parallel to the coil to have the largest footprint. I used a nickel because it falls in the mid/lower conductor range that is more subject to phase shift if there was any frequency change vs a high conductor silver or copper coin that shift less as their phase angles are much higher. Keep in mind it is a common practice to use a carbon spray on the inside of coil housings for emi shielding. Also keep in mind even if your crawling around on your belly with your coil upside down you should still not have any issues.

Well after looking at features between them don't you guys think they should have at least included a salt mode for their lower end version? Can't tell ya how many times I have seen new people at the beach with their machines.

Took my machines and tested the coils with my frequency tester on my scope without and with a Steve G lower carbon shaft perpendicular and layed across the coil. I could not see any frequency change nor any depth change. This was done on my Tejon (17khz, D2 (14khz and 40khz mf) and Gold Racer (56khz). Maybe if the carbon shaft is thick enough but no issue with the Steve G shafts. I don't think they pose any problem.