18 inch coil Works!!! A big thanks to Carl and everyone...

[Charles (Upstate NY USA)]

VICTORY!!! My custom 18 inch coil works now thanks to tips from Carl and others. I went back to my measurements of factory coils and pictures and xrays of same and said okay where am I out of spec. My TX was right on the money in LCR and Q. But RX had a Q 7x the other coils. I went two guages lighter I got the Q down to within 10% of the others and what do you know the darn thing works, no hint of the prior problem. Man this thing is scary on my gold ring, it was chirping in an air test at about 20 inches and the Explorer don't air test well.

The second big victory was on the overall weight, I got it down to 1 pound 8oz, 1oz lighter than my factory 15 inch coil.

Tomorrow morning we'll take this bad boy out to some parks.

Thanks again folks!

[Richard]

Re: 18 inch coil Works!!! A big thanks to Carl and everyone...

Charles: I have made a few PI coils. Some Up to 4 feet diam bundled coils. Spiral ones too(but 9" only on spiral ones) The way I make´m is to reduce the gauge and turns too. However I do this with the machine switched on pot all way back and unwinding until I manage to silence it. With my 9 inch and up to 16 inches I can´t get to make em sing to my gold ring more that 5 inches away and this I find good. Perhaps I am missing something or I became stagnant with my detector which is a Mark Stuart one. Could not manage to shield the coils on this circuit.Can anyone recomend me a good PI circuit to build so That I could detect a gold ring say at 10". This would be fenomenal. Cheers Richard

[Beachcomber]

Way to Go Charles!!! Sounds like you solved your dilemma!!!!

Looking forward to hearing how it works in the Field!!!

HH

Beachcomber

[Joe]

Re: 18 inch coil Works!!! A big thanks to Carl and everyone...

Is this a pulse coil and where can I read about and get the plans? What did you coat it with? HH Joe

[Charles (Upstate NY USA)]

Its a double-D for a Minelab Explorer

At present I'm using a urethane resin, its thin as water so it flows great and all the bubbles rise up and vanish before it sets up, zero smell or fumes, cures to a shore D hardness of 72 i.e. its quite rigid BUT...I'm finding that its reactive to certain things like the nickel spray on shielding paint I have been using. It reacts by generating a zillion tiny bubbles which pretty much ruin the coil, it will work but looks like hell. I found that if I sealed the sheilding spray with a coat of spray on enamel first that eliminated the problem but thats an extra step that I don't want.