A Military Coil

[Tilladude]

I scored a military coil yesterday on the "bay" and then spent all day today fighting a browser problem. Below is the write-up the seller gave for it:

US MILITARY MINE DETECTOR DUAL COIL METAL DETECTOR HEAD

THE OUTER COIL IS APPROXIMATELY 10.5", INNER COIL APPROXIMATELY 7.5" - THE PLUG HAS SIX PINS AND IS APPROXIMATELY 1/2" CABLE IS 69 INCHES LONG

THE CONNECTOR ON THE END OF THE CABLE CAN BE CUT OFF AND YOU CAN SOLDER ON YOUR OWN CONNECTOR - WHEN YOU CUT OFF THE END OF THE CONNECTOR THERE IS A BLACK WIRE AND A CLEAR WIRE, THE RESISTANCE ACROSS IS 1.0 OHMS - ACROSS THE RED WIRE AND THE GRAY WIRE THE RESISTANCE ACROSS IS 2.8 OHMS

THE 3/4" (INSIDE DIAMETER) ADAPTER THAT CONNECTS THE COIL TO THE SHAFT OF THE METAL DETECTOR COMES WITH A NYLON BOLT & NUT

THIS IS A VERY IMPORTANT FACTOR BECAUSE WITH OUT THE ADAPTER, YOU CAN NOT CONNECT THE COIL PROPERLY TO THE SHAFT

As you can see he gave resistance readings for the coils within, I will take inductance readings when it falls on my doorstep and report the results and doubtless have several questions at that time.

Y'all take care out there,

Dennis

[detectoman]

wow

[Tilladude]

A Military Coil

I forgot to say that the coil cost me $9.99 and shipping is $10.97.

Take care out there,

Dennis

[detectoman]

thanks guy

[Tilladude]

Can you believe this, first I get this coil $20.00 shpg. and all and then the drops it on my door step this morning. Now I won it at 7 o'clock pm PST/10 o'clock EST on the 25 and 2 days later it's in my hands.

Anywho down to business, my Tenma C,R,L meter says blk/clr wires (inner coil?) is .86 ohms & 255uH and the blu/red wires (large coil?) is 2.61 ohms and 466uH. The cable is 4 wire unshielded & other than a little dust here and there the coil looks like it was hardly used.

I'm thinking this might be a good coil for the TGSL I've got in the works.

Any opinions greatfully accepted.

Dennis

[Qiaozhi]

Anywho down to business, my Tenma C,R,L meter says blk/clr wires (inner coil?) is .86 ohms & 255uH and the blu/red wires (large coil?) is 2.61 ohms and 466uH. The cable is 4 wire unshielded & other than a little dust here and there the coil looks like it was hardly used.

I'm thinking this might be a good coil for the TGSL I've got in the works.

Any opinions greatfully accepted.

Dennis

The inductance values are too low for the TGSL circuit.

[Tilladude]

Yup I thought about that after I posted, the TGSL coil has to be in the mH range. I'm wonder how good it might be for a 2 coil PI, I could make the necessary mod to my Gary's PI, I'll have to get up with Gary get a read from him.

Dennis

[Carl-NC]

Also, this coil in not induction-balanced, so it will only work on a PI. I bought a couple of these a few years ago (same guy) and it works nicely.

[Geo]

[Quote = Carl-NC? 111060]Also, this coil in not induction-balanced, so it will only work on a PI. I bought a couple of these a few years ago (same guy) and it works nicely. [/ Quote]

Carl, can you give more info?
Has it the ability to work at 10us? And also is it a shielding coil?

Regards

[Carl-NC]

I think it's shielded, I don't know that I ever tried it at 10us. The coils are commonly offered on eBay, apparently somebody bought a whole bunch of them.

[Tilladude]

They probably bought them at US Gov. auction, there are sites all over the states, there is one north of me at Ft. Lewis Army Post.

Dennis

[Geo]

They probably bought them at US Gov. auction, there are sites all over the states, there is one north of me at Ft. Lewis Army Post.

Dennis

Any link????

[Tilladude]

Geo,

These auctions are held at regional military bases and you have to be present on the day of the close to pay for and pick-up, usually with a big truck because these are pallet lots, your goods or have an agent there on your behalf.

Dennis

[Geo]

Geo,

These auctions are held at regional military bases and you have to be present on the day of the close to pay for and pick-up, usually with a big truck because these are pallet lots, your goods or have an agent there on your behalf.

Dennis

Thanks Dennis.
So it is difficult to me to buy a coil same to yours.

Regards

[Tilladude]

Geo,

I'm afraid so, at least buying more than one would be, but there are bunches and bunches of better coils out there if you just keep looking.

I set up my PI for 2 coil and put a plug on the mil coil and got zip, zero, nada. I think maybe the smaller coils inductance (255 uH) might be the culprit.

Right now I'm dreaming up a big OO coil arrangement that will either be a drag mat type or a low to the ground towed type. The big problem would be in finding a 3' X 5' mat to put the 30" coils on. The towed type would be easier because I would use plastic pipe although getting 40 some rounds of wire inside the pipe would take some doing. Like I said it's in the dream stage right now, we'll see what happens.

Take care,
Dennis