What is a good inductance meter?

[punagold]

I'd like to build my first coil for my Garrett ATX. I need to get a meter to measure my stock DD coil but I am not sure what range of values a meter needs to be able to read. Can someone point me in the right direction? Maybe on Amazon? Thanks. My goal is to make something around 20" DD. Can this be done without an oscilloscope?

[WM6]

Almost all "eBay" RLC meters are good enough.
You cannot measure nothing without dismantle your present coil, cause ATX has active circuit inside coils.
Search for "Garrett Infinium coil" here, it is pretty the same inner design.
On other side, stock gamma coils for ATX are optimal.

[punagold]

I found a thread that showed the inside of an infinium dd coil. Also found a schematic that shows the infinium dd. Pardon my ignorance, but is that a resistor on the RX coil? It's labeled(680 ohm 1/4W) I actually use the 10x14 infinium dd on my atx because I hate the atx shaft. I've also used the infinium 7x10dd coil with success.

Thanks for the info on the RLC meter. I will check it out.

Stock gamma coils for the ATX are optimal? Can you elaborate at little more on that? I have never heard of anything else besides infinium dd coils that could be used on the ATX. Thanks

[WM6]

Stock gamma coils for the ATX are optimal? Can you elaborate at little more on that? I have never heard of anything else besides infinium dd coils that could be used on the ATX. Thanks

Yes optimal. It is hard to understand to me what other coil you need apart from this stock coils? You say 20" coil to build, but such coil already exist as stock coil (I tested it, in short: to heavy for everyday search):

[punagold]

I would love the have the 20" deepseeker. The problem is that it cost over $500 and comes attached to the heavy shaft. I would have to cut the shaft off and build a mount for a standard rod. If I have to do all of that work, I might as will make the whole thing for much less cost if possible. My goal is to make either a light weight mono or dd 20" Since I have no mono to test, but do have a dd, my focus is on the dd. Since it is not a commercial coil, I can make it a little more delicate in order to save some weight.

I am experienced in working with epoxy resin but I am fairly clueless when it comes to electronics but I am a quick learner do it yourself kind of guy. I hope that my lack of knowledge and my questions do not irritate all of you electronic wizards. I have been trying to read as much off of the forum and other sites before I ask my questions. My biggest fear is that I make a coil, plug it in, and fry my ATX. I would like to think that if it test the same as stock coils before it is plugged in, that all will be safe. I do have a cord and plug already so that solves one problem. Now I just need to figure how to stretch the dd to 20". Maybe something like 20 x 8", if that is possible.

Have you have tested the 20" mono for resistance an inductance?

Thanks again.

[WM6]

Have you have tested the 20" mono for resistance an inductance?

Thanks again.

I even didn't test it for detection depth, cause it is so big to nut suit in my testing plant:



Otherwise, so called "mono" coil for Infinium and ATX are not mono (single loop inside) in fact. Such mono (from outside) coil are in fact some sort of concentric coils:



So you can follow schematic for Infinium "mono" coil to build bigger ATX coil.

Test:

http://australianelectronicgoldprosp...rett-atx-test/

[punagold]

According to Garrett, I can safely use the infinium dd coils on the ATX, but not the infinium mono coils. I suspect the ATX mono is designed differently than the infinium mono.

[WM6]

Yes, inner circuit of Infinium DD coil is designed differently than inner circuit of Infinium mono coil.

Both, Infinium mono and DD coil have TX and RX loop.

ATX has 8" mono loop too, from outside practically the same as Infinium 8" mono.

What Garrett say, what is reason to not be replaceable? Is ATX mono in whole different than Infinium mono? In other words: is ATX mono equipped with same inner circuit as Infinium DD and not as Infinium mono?

[punagold]

Thanks for doing the depth test on the ATX. Very interesting the extra depth on non-motion.

[punagold]

That is my understanding. They will not go into detail as to why the infinium dd works on ATX but infinium mono does not work.

[WM6]

Infinium mono coil has active circuit (2 TR etc.) inside, while Infinium DD only passive (damping) R inside coil.

If only DD suit to ATX, it is even easily to reproduce:

Build first coil identically to Infinium DD coil. Follow dimension of loops and its resistance given at diagram, measure inductance and then adapt this to bigger diameter (following measured inductance in first line):

[punagold]

Can I skip building the identical coil and just measure the stock coil that I already have, or does the 608 ohm 1/4 W resistor complicate taking accurate resistance and inductance measurements? Is it correct to assume that if I can match inductance and resistance of a PI coil that the matching coil will operate in the same manner?

[baum7154]

Can I skip building the identical coil and just measure the stock coil that I already have, or does the 608 ohm 1/4 W resistor complicate taking accurate resistance and inductance measurements? Is it correct to assume that if I can match inductance and resistance of a PI coil that the matching coil will operate in the same manner?

____________________________________

In addition to matching the inductance and resistance of the coil you will have to measure the self resonant frequency and make it equal to or faster than the original coil. This measurement is with the feedline and shielding all in place. Essentially the SRF measurement will take into account the inter-winding and distributed capacitance that will have the effect of slowing a coil down. The goal is to have as little capacitance as possible in the system.

Regards,

Dan

[punagold]

How does one measure the self resonant frequency? Also, What steps does one take in order to have as little capacitance as possible? Minimal shielding? tighter windings? small insulation? litz wire? Thanks for your response.