Garrett Infinum/ATX mono coil

[Altra]

The mono loops have a TX and RX winding which are fully coupled and not inductively balanced. The Tx/Rx are wound together. The Tx is 18awg tin plate stranded with pvc insulation(258uH 0.6R). The Rx is about 30awg single strand teflon or kynar insulation(228uH 6.0R). Inside the coil is a protection pcb. During the Tx and flyback period the rx coil is disconnected from the pre-amp. The circuit uses two depletion-mode n-fets which are high impedance during Tx and low impedance during sampling. There is an adjustment pot, which I assume is for trimming the off time? Photos of the ATX protection pcb appear to be very similar with the addition of ferrite beads on all the lines. This may be for the military aspects and EMP protection? The Infinium/ATX DD coils have no protection circuit and are well balanced.

[moodz]

Great info ... what is the shielding arrangement around the coil and is the cable shielded ...

[Orbit]

Great job Altra

[Aziz]

Yeah, great job Altra!

I see, that the coil arrangement is destined to separate TX/RX coil configuration (no induction balance).
So a larger TX coil with a smaller RX coil arrangements can be easily realized.
The effective coil size would be the geometric mean of the diameters of TX and RX.

Example:
TX: 18 inch diameter
RX: 9 inch diameter
Effective size: sqrt(18*9) = 12.7 inch diameter

[Altra]

The cable consists of two twisted pairs, a overall foil shield and a tinned drain wire. The drain wire (shield) and Rx black are connected together in the cable connector. The coil itself is shielded with standard graphite paint connected to the drain wire. I don't have an Infinum or ATX to varify, but I believe the black wire and shield are connected to analog ground.

I found that this protection circuit adds about 3uS to the minimum sample time delay. This is with my own coil and ATX style regenerative tx circuit. So maybe my test set up isn't optimal? It would be nice to have a Garrett to test verify what the actual performance should be.

[nickel_n]

Did i also see a post maybe two with the schematic diagrams of the pcb's yesterday and missing today or i imagining it?

[Altra]

Hi, I had problems uploading some of the files and others were corrupted. The schematic is the pdf file and the pcb is a jpg atx_infiniumcoil5 up in the first post

[nickel_n]

there is no pdf file on the first post i can see
only four jpx files

[Altra]

Not sure what the problem is? I just downloaded the pdf from the first post and reposting here

Garrett Infinium Mono loop.pdf

[nickel_n]

Thanks Altra
i can see it now.maybe there was a problem at my end