GA-52CX Calibration??

[bklein]

If it were mine I’d spray some of that bolt-loosener stuff and let it sit awhile before trying this. That volume control he’s hitting with the hammer is $42 plus shipping.

There is a “talk to our techs” option on their website. I left an inquiry.
There are several businesses and individuals that work on these. It’s all kept secret on how…

[Altra]

Hopefully, I do not need to do this: https://youtu.be/SnfnzlLM69I?si=qFZeKvtvtTKD5FoF

Thanks for posting this video. I have a very old GA-52 and wanted to remove the sensors from the tube . I have hesitated up to now, not wanting to damage or destroy anything.

Have you tried contacting their service department? Some times a tech will give some good info without sending the unit in.

[bklein]

Hopefully, I do not need to do this: https://youtu.be/SnfnzlLM69I?si=qFZeKvtvtTKD5FoF

[bklein]

Ok, given that, what would you guess each of the 3 trimpots do and how would you go about optimising operation? I like your earlier suggestion of trimpot names but away from a target the tone and sensitivity is like the other one I have. Should I be moving a small target up and down the shaft and adjusting something like a differential gain?
I think I’m going to have to find an ex-employee with LinkedIn…

[Altra]

Found this video regarding gradiometer magnetometers

https://www.youtube.com/embed/sTFIUyL0-Ow?

[bklein]

I just received another GA-52cx. It seems a bit “off” from another one I have. The general sensitivity as I go through the sensitivity switch settings seems a little less than the other one and the tone pitch is not the same - but close. This and it has some FM going on that isn’t desired. There are 3 trimpots - two of them have been played with by the previous owner. The third is sealed in place.

Any ideas on a calibration process?
Would it be something that would not require special equipment?

[Carl-NC]

So, what is meant by alignment?

I'm not sure what Orbit is doing. In my FGM-based mag, both sensors are aligned in the tube like this:


One sensor is fixed, the other is mechanically adjusted for alignment.
The whole construction article is here.

[Daves]

I personally line them up vertically down towards the ground.!?

Is the flc-100 sensor spacing 12cm appropriate?

I set up the sensors with 12cm intervals facing downwards. I am receiving data from the sensor, when I turn the sensor right, left, up, down, the dc data increases or decreases. What is the alignment, zeroing, calibration etc. procedure I need to do before I start processing this data? In other words, in which direction should I hold them and what operations should I do?

[Orbit]

So, what is meant by alignment? Is it to align the sensor so that it points perpendicular to the ground? Or is alignment = a software procedure?

I personally line them up vertically down towards the ground.!?

[Daves]

With a single axis gradiometer, you want both sensors exactly aligned axially so that when you rotate the mag on that axis there is no response. If one of the sensors is slightly angled, then there will be an increasing/decreasing response as you rotate the mag.

So, what is meant by alignment? Is it to align the sensor so that it points perpendicular to the ground? Or is alignment = a software procedure?

[Carl-NC]

With a single axis gradiometer, you want both sensors exactly aligned axially so that when you rotate the mag on that axis there is no response. If one of the sensors is slightly angled, then there will be an increasing/decreasing response as you rotate the mag.

[Daves]

I can't explain it because it depends on the mag design. But, ultimately, you want the mag to have no response when it is rotated in free space. A little like GB, kinda sorta.

DC data comes from the sensors, what is the alignment that will be done on the north-south or a different axis? I couldn't fully understand this. (If we are talking about FLC-100)
We could do this at least with a target in the metal detector. What will we convert the DC data to and then align?
I couldn't fully understand the alignment procedure.
Orbit

[Carl-NC]

When it rotates in free space? If you adjust the sensors when the pipe is horizontal with that and the pipe is in a position for example north south! Any rotation in other directions will cause a decrease or increase in the frequency output on the sensors!

That is true for a simple 2-sensor design. I assume most commercial mags (for utilities, like the GA-52CX) include 3-axis sensors; the Z-axis for main detection, and X & Y axes for Earth field calibration. When you have sensors on all 3 axes you can calibrate it to rotate freely in Earth field with no response.

[Orbit]

On the Expore 5000 or 3000, the sensor outputs enter the precise rial to rial, one on the inverting input, one on, not inverting, as we lower the sensors towards the ground, if there is no metal in that place, a kind of ground balance is performed, one sensor pulls in the plus, the other in the minus, and we have at the output of the amplifiers, the voltage is zero, when the sensors pass over the metal, the sensors react depending on which side the object is on, and the voltage goes to plus or minus as soon as we cross that field, thanks to that accessory, the sensors perform some kind of automatic calibration!

[Orbit]

If I forgot to write, as I said, the processor, for example, expects 500mv, but the measurement in the minus starts at 400mv and in the plus of 600mv, that's what I called the neutral field! Because there is a slight drift condition due to component voltages or external disturbances. That neutral field affects a slightly lower sensitivity if the measurement starts immediately, the sensitivity is higher with the possibility of giving false readings due to the above.