GPX homemade large coil

[IBGold]

Hi GP,

I do not think that is correct as we use 36/.2mm in our home made Litz for an 18" mono and that works out including coax at .4 ohms at the plug are you sure it is not 72/.16 mm.

Regards, Ian.

[GoldPandemic]

Oh, and that is for Minelab GPX series detectors?
Cause that is what someone said they found in their Minelab 18".
Can you tell me how many windings you use?

Thanks

[IBGold]

For an 18" bundle wound coil 17 turns and yes it will work with a GPX.

Regards, Ian.

[GoldPandemic]

Have you tried constructing a larger diametre? What is your resistance?
Perhaps you get a little more interference than the minelab branded 18".

[IBGold]

Yes I have built 800mm x 600mm with a resistance of .4 ohms and an 1800mm round at 0.4 ohms but this is a ground loop.

Regards, Ian.

[GoldPandemic]

Thanks I'll try to add some more turns to my coil.

What were the Inductance readings for those coils you made?

[IBGold]

Hi GP,

The 800 x 600 has a finished inductance of 312uh and the 1800mm ground loop has an inductance of 406uh it was designed this way as it has its own TX unit and battery driven in unison from the main detector is all I can say Pictures of both attached.

Regards, Ian.

[GoldPandemic]

"is all I can say" is that because its a secret?
Do you need to have a separate TX unit? I don't want to do it that way.
I reckon if I up the wire count I can lower the Inductance to somewhere closer to 280mH. But will be costly ordering lots of Linz wire for experimentation (sure I can off load it on ebay for other coil makers).

[IBGold]

Hi GP only the ground loop has the extra TX unit because it has advantages that way and that is the way we are doing it, upping the strand count will allow you to lower the inductance while keeping the resistance where you want it.

Regards, Ian.

[6666]

Hi Ian
would you mind saying a few words on how you are useing the ground loop system thanks