DD coils for minelab pi units

[mario]

Hello,

Im trying to construct my own DD coil. Any one know the target rx/tx pinout and inductance for the Minelab DD pi units?

I have found the coil requirements for the monos, but not the DDs.

Thank you

[IBGold]

Hi Mario,
I have given the pin outs before but again for you.
Pin1 RX Shield and linked to pin 5 TX shield
Pin2 RX.
Pin4 TX link to Pin3.
The TX inductance 300uh and 0.4 ohms around 17AWG wire.
RX inductance between 300uh and 450uh and my preference Litz wire around 28AWG.
Have fun and keep the capacitance low.
Regards, Ian.

[mario]

You're the best!

I couldn't find the specifications among the now countless threads.

I also have an old stock DD minelab coil and is a very poor performer (non-pro series 11" ). After taking inductance measurements, I measured inductance at 415uH.

I wasn't sure if the inductance was the reason why I couldn't detect much of anything.


Can you tell me what is the ideal inductance for RX of the DD coils? I'm trying to make one 17".

Thanks

[IBGold]

Hi Mario,
As close as you can get to 450 uh is best.
Regards, Ian.

[mario]

There you go guys, hopefully this will make the information more portable.

Does the resistance of RX for DD also a required .4 ohm?

It's going to be much more difficult to achieve this resistance on the larger coils, no doubt. Please let me know so that I may update the image.

Thanks!

[IBGold]

Hi Mario,
RX coil resistance is usually between 5 and 15 ohms dependant on the wire used to wind it with.
Regards, Ian.

[ghaj]

separate TX/RX coils?

Hi Mario,
I have given the pin outs before but again for you.
Pin1 RX Shield and linked to pin 5 TX shield
Pin2 RX.
Pin4 TX link to Pin3.
The TX inductance 300uh and 0.4 ohms around 17AWG wire.
RX inductance between 300uh and 450uh and my preference Litz wire around 28AWG.
Have fun and keep the capacitance low.
Regards, Ian.

Dear IBGold
I can't understand TX and RX! I thought PI detectors has just one coil doing both transmit/receive tasks. Do you mean that in Double D coils, transmit and receive coils are separate? Thanks.

[ghaj]

There you go guys, hopefully this will make the information more portable.

Does the resistance of RX for DD also a required .4 ohm?

It's going to be much more difficult to achieve this resistance on the larger coils, no doubt. Please let me know so that I may update the image.

Thanks!

Dear Mario,
Could u put other specs of minelab SD2000 coils like number of turns, no. of wire used, diameter of the loop, material of wire and shield and so on? you know, I don't access instruments for measuring inductance Thanks a lot.