Garrett ACE and AT coils

[Hannu]

I had chance to compare ACE and AT-series coils.

measured from plug
ACE 6.5" x 9": 2.5mH / 4.7ohm and 1.89mH / 31.5ohm
ACE dd: 2.5mH / 4.9 ohm and 1.90mH / 28.6ohm
AT dd: 2.5mH / 4.8ohm and 1.90mH / 24.4ohm

Big question - what is difference? Both have trimmer inside. I don't have AT coil internal schema.

[Skippy]

It's likely that the residual null signal is lower for the AT coil than the Ace one. The AT coil's shielding might be better, too.
I say this because the AT will obviously run at higher gain than the Ace, maybe double/triple, so coil nulling is more critical.

[Hannu]

Now I have broken AT DD coil. RX side had shortcut in coil side. Cable and plug were ok.
I took pcb out and it looks same like ACE-series. Only 3 componets. Zero ohm resistor(jumper), 100 ohm trimmer resistor and 12nF capasitor.3 coils. 2.5mH 4.2ohm, 1.7mH 8.3ohm and one coil with very low inductance and resistance (tuning coil pallel with trimmer resistor . series with RX coil).

Next thing is put all back without pcb and test it with ACE

[Hannu]

Fixed and working on test bench. Capacitor is left out.

[Hannu]

AT's PCB. Trimmer is placed under small sticker top side of coil.

[Hannu]

Today i made adaptor to connect my second AT coil to ACE250. It's working good on kitchen table. I see no difference.
Is it same coil for both machines? Does anybody really know?

[kt315]

Garrett Ace 150...........................6.5 kHz
Garrett Ace 250...........................6.5 kHz
Garrett Ace 350...........................8.25 kHz
Garrett AT Pro............................15 kHz
Garrett AT Gold..........................18 kHz

wrong data on frequencies? can somebody give a respect light to right data?

[sinclairuser]

there must be some tolerance, kt's numbers above match the garrett specs, when you buy an ace coil the same one is for the ace range 150,250 and 350/euro, as said above the at versions may be better shielded.

[Hannu]

Checked ace250 + ace dd coil. result 6.73kHz.

[Hannu]

Tested 6 coils with ace250.

results
-------
ACE DD 8.5" x 11" - 6.73kHz
ACE CC 6.5" x 9" - 6.71 kHz
ACE CC 6.5" x 9" - 6.73 kHz
ACE CC 9.5" x 12" - 6.78 kHz
ACE sniper 4.5" - 6.75 kHz
AT DD 8.5" x 11" coil connected to ACE - 6.75 kHz

[bbc0]

Can someone tell which principle the the Ace 250 operates under please. I just purchased a used one and am new at this. I notice that it has no adjustment for ground effects and assume that this is most likely due to it's design principles.

[FatBob]

Well here's a schematic that is supposed to be ACE.

Maybe R48 is the ground balance?

Many detectors have a preset ground balance that should work most anywhere...

[Davor]

In a micro you may combine s portion of disc signal to achieve a better GB, provided the disc channel does not saturate. If you allow saturation, a perfect trigonometry becomes impossible.

[bbc0]

In a micro you may combine s portion of disc signal to achieve a better GB, provided the disc channel does not saturate. If you allow saturation, a perfect trigonometry becomes impossible.

Say what?

Barry

[Davor]

Seek a schematic of Fisher 1265 and see how it handles discrimination. It happens in a baseband (1-10Hz) and that's what ACE see on its ACD inputs.