1$ Gold coin v.d.i. question

[supafly136]

went to a large coin dealer and air tested 2 indian head 1$ gold coins and it constantly came up as vdi 50 and zinc penny.

in analyze mode, the 7.5 frequency was the very dominant one. today, found a small silver 925 ring, NV size 4 with new Super 12, 3 frequency coin and jewelry gain of 3, boost off, at 2 inches deep at park and it read the same thing. gain of 1 with the d2 inside store, nice and quiet using 3 frequency best data in coin and jewelry mode on all 3 items. any ideas as to why the dominant frequency wasnt 22.5 for the gold coins and 2.5 for the sterling ring?

thx in advance

 

[Larry (IL)]

The dominate frequency is determined by mass AND conductivity. The gold dollar had enough mass that 7.5 picked it up better and the low mass on the high conductor ring, the same reason.

 

[supafly136]

thats gonna take a while for me to grasp lolol. i would have thought with the coin directly in front of the coil, and being 90% gold, that 22.5 would have dominated. so are yor saying a larger gold coin .... is there any u.s. gold coin that would register 22.5 dominant?

thx

 

[supafly136]

if it helps, 7.5 on all three items was dominant.

 

[Larry (IL)]

I doubt it, the $1 is the smallest US gold coin that I know of.

 

[Rob (IL)]

Best Frequency to Use is determined not only by metal content, but also size and thickness. For thicker coins with high silver content there is no question that 2.5 kHz will hit harder than 22.5 kHz. For US nickels 22.5 kHz will hit hardest. 22.5 kHz may also work best on small thin coins, even those with high silver content, due to skin effect. High frequency may also work best on low silver content coinage. 7.5 kHz is typically better on copper coins. Test the detector for the items you want to find. If all you want is US silver, then you should use 2.5 kHz. If all you want are thin gold rings or small nuggets, then select 22.5 kHz. If you want the best depth on a wide range of targets, use 3 frequencies.

 

[supafly136]

hmmmm. thats weird, because i have small gold rings and chains 14k that constantly show 22.5 dominant at same settings.

i'll dig em all.!

 

[triplehooked]

As Larry had stated, a gold ring or chain does not have the mass of the gold coin, but they do have the higher conductivity for the 22.5kHz freq. to register as dominate. The dollar coin had the mass of a zinc penny, AND the conductivity of jewelry, so the middle frequency was dominate. Kind of like two extremes meeting in the middle. I agree, it takes a bit to wrap your head around... But as usual, the mods do an excellent job of explaining it.

 

[supafly136]

hey thx for the replys guys.

but i AM testing for the items i want to find. thats why i went to the coin dealer to test the vdi for the gold dollar. now dont get me wrong, i love my machine, but i still just cant comprehend that in 3 frequency pinpoint on a 90% gold coin, why the detctor doesnt show 22.5 dominant. there is no ground to deal with skewing the results, and the dollar is airtested facing flat in front of the coil an inch away. i mentioned it to Mary at Whites bout a week ago and she said it was weird for it to do that. i said no biggie, prolly just a fluke. then it happened on the sterling ring. i realize all gold jewelry is going to jump all over the place when it comes to the vdi, but were talkin 90% gold using analyze in polar plot, and same results in pinpoint. dont really matter much to me cuz as i said, ill dig it all. just would be a shame for someone to pass up a gold coin cuz the analyze or pinpoint results didnt show there was an almost solid chunk of gold under the coil.

also, im sure you guys know much more than i, and i may be overthinkin it lol

thx again for the input

 

[Blind Squirrel]

Hi Supafly--

The 50 VDI reading on a $1 gold did not make sense to me. I put my 12" coil on and matched your settings and performed tests. You didn't mention (although it makes little difference) which type $1 gold you used. So I tested types 1, 2 and 3. They are all PCGS graded coins so the encapsulation could have an influence on the readings. They all VDI'd in the 10 to 15 range and all pinpointed with 22.5 dominant. What got me thinking then was that you specifically labeled them as "Indians" so I tested NGC graded $2.5 and $5 Indians. The $2.5 Indian VDI'd at 31 to 34 and pinpointed with 7.5 dominant and the $5 Indian VDI'd at 49 to 50 with 7.5 dominant. I am convinced that you air tested a $5 Indian, unless you were wearing a wrist watch or other jewelery that influenced your test. I hope that this helps.

Good find on the silver ring!

Happy Hunting
Blind Squirrel

 

[Neil in West Jersey]

My wife has a heavy Tiffany ring that is made up of tiny silver links. Even though it is heavy and sterling, the VDI is only 7 and the dominant frequency is 22.5KHz. There are many factors that determine the dominant frequency. Size, density, conductivity are the three that have the highest impact.

 

[Blind Squirrel]

Hi Larry--

Although technically not a U.S. minted coin , don't forget about the private mint fractional California Gold in quarter and half $ denominations. They are REALLY small (1852-1856).

Happy Hunting
Blind Squirrel

 

[Blind Squirrel]

Hi Neil--

That's a good reason to dig all solid audio responses, regardless of VDI !

Happy Hunting
Blind Squirrel

 

[supafly136]

hey thx very much Squirrel and Neil for the tests.

yes i believe your right about that, it was a $5 coin. srry bout that.

thats great to know for sure that theres consistency on the exact same gold coins.

i can understand all the jewelry being totally random

thx again to all who posted. now im gonna back track to the few zinc penny hits i passed up lol.

fantastic info here!

 

[Butch in Colorado]

n/t

 

[nw1886]

My wife has a heavy Tiffany ring that is made up of tiny silver links. Even though it is heavy and sterling, the VDI is only 7 and the dominant frequency is 22.5KHz. There are many factors that determine the dominant frequency. Size, density, conductivity are the three that have the highest impact.

There is one thing to remember on "link" jewelry is electronics love a circuit.....priority. (Each link is one and they are small.) A chain hunt and a "regular" jewelry hunt are two different animals and shape/length of signal is the focus. A good pinpointer (and a developed ear for a scratchy signal) will put these in your pouch.....and you will still pass over a lot of them. Chain is a "frontier" mostly unrealized by us all.