Shield wiring from a Teknetics DD-coil

[Germanicus]

I made a DD-Coil for my Teknetics G2 (Clone, see also http://www.geotech1.com/forums/showt...er-Gold-Bug-DP ), but it doesn’t work. The detector only displays “Overload”. Does anybody know the schematics of a original Teknetic DD- coil? How are the shields of the coils connected? Does someone know how the compatible coils (Detech or Nell) are connected (shields)?
The connection of the booth shields from the coils to the Rx-coil doesn’t make much sense in my opinion.
On Pin 5 (where I suppose the shields) seems only the Cable-shield to be connected. (?)
Here are the data of my DIY-coil:
coil Pin1-P2: 44 Ohm, ~ 9,9mH (original has ~9,2mH)
coil P3-P4: 1,9 Ohm, ~ 0,88mH


Attachments: the current wiring plan, the DIY-Coil

[Qiaozhi]

The detector only displays “Overload”.

If it's displaying "Overload", then you probably don't have the coils balanced properly.

[Germanicus]

I balanced the coil as good than i Could with a osziloscope. But i think that i have to much Noise On them because of the false shielding. May be the Big coil has too much mH?

[Germanicus]

Ok, I disassembled the improper coil with 9,9mH and removed some windings. Now I have got 9,16mH which is nearly the same than the original coil has. I would like to make the shield with graphit-spray. Is it a problem when shield of the coils is made from different style (kOhm vs mOhm) ? My other coil (which I cant remove because of many hot clue) has shielding made of aluminium-foil.

[Hannu]

Today I made DD coil for gold bug and had same "overload" problem. After balancing coil second time with SMW2-board it was possible get lower RX Vpp value than original 5" coil with same setup and overload message did not show up again. I used 10 layers graphit 33 spray but i have no experience what is good R value for shielding.