How does a manufacturer test a detector?

[bklein]

I am wondering how a manufacturer tests a detector. Do they do an air test with a few targets or what?
We all have had experiences where the detector doesn't seem sensitive as others we hear about of the same model.
Often the coil is replaced as a result.
But what is the manufacturer really doing to check sensitivity of a detector?
I had a couple coils replaced for my CTX, had issues with the EQ800, and now am suspecting something wrong with my Whites surf dual field as it is only picking up a gold ring at 4". It is straight from the repair center. On the same target at the same wet beach site same day my CTX was hitting it at about 15" and my GP Extreme like 21". I had specifically asked in my return letter to check sensitivity to small gold - I didn't actually try something smaller. I stuck with the rather hefty gold ring to test with and am a bit upset with the results.
(Gain full on, pulse width, minimum)

[Koala]

my Baracuda which is very similar to the Surf does 13" on a medium size ladies ring.


4" doesn't sound right.

[bklein]

Browsing threads I see groupings of 6-8” and 13”. Mine is really bad at 4”.

[Koala]

Distance will alter according to

karat
size
and if its a complete circle


the one I test with is 6.5 grams

[green]

I would suggest using a standard set of targets. Maybe using regular strength aluminum foil. Suggested targets would have a time constant range of about 1.5us to 25us. Could make a set and fill in the blanks if interested. Maybe rings would have a TC range similar to the test targets?

[Mark-VA]

Very important note on this subject. If the ring has a fracture or brake in the metal, this will cause either a complete failure of air test or reduce distance by maybe +90%. Case in point, years ago I dug a really nice gold engagement ring which gave a solid tone and ID before digging. Once out of the ground I could only get a signal by rubbing the ring on the coil. Then I noticed the ring was broken. When I squeezed the ring together the audio and ID came through very clear. One more note, the day I dug the ring the soil was saturated with water. The wet ground needed for me to find the ring in the first place.

[Koala]

I would suggest using a standard set of targets. Maybe using regular strength aluminum foil. Suggested targets would have a time constant range of about 1.5us to 25us. Could make a set and fill in the blanks if interested. Maybe rings would have a TC range similar to the test targets?

Right or wrong I read the original post as sarcasm. They sent me my machine back that can only pick up a heavy gold ring at 4 inches

And is my machine working correctly.

[Koala]

Is it just gold that's bad.


What's it like on a copper coin?

[bklein]

Air test on a standard set of targets should be first run at it - but not enough. I am upset that I will have to return it but I am hesitant to because I got it this way. I want to run a respected series of tests beforehand so they duplicate the results, then fix “it”, and get better results. I have respectable test equipment to tweak it myself and may do that. But a pi is supposed to do better on in-sand targets than air targets and this one fails that. If all they do is tweak sample timing or do an air test these will pass and ship to customers.
I didn’t check but perhaps the pulse delay pot is faulty? Setting was at minimum.

[Koala]

Air test on a standard set of targets should be first run at it - but not enough. I am upset that I will have to return it but I am hesitant to because I got it this way. I want to run a respected series of tests beforehand so they duplicate the results, then fix ?it?, and get better results. I have respectable test equipment to tweak it myself and may do that. But a pi is supposed to do better on in-sand targets than air targets and this one fails that. If all they do is tweak sample timing or do an air test these will pass and ship to customers.
I didn?t check but perhaps the pulse delay pot is faulty? Setting was at minimum.

delay is a bit of a compromise. This was the best I could get

as you can see here gold is down to get a reasonable depth on the fibula


https://www.geotech1.com/forums/atta...0&d=1459631333

few standard things in there. 50 cal and 303

[bklein]

Whites say they set 15uS timing and look for 5-6” on a nickel and they’re good. Hmmmm.

[bklein]

Tried a nickel vs my test gold ring. Detects the nickel better. Not good.

[Koala]

Tried a nickel vs my test gold ring. Detects the nickel better. Not good.

and a copper coin ?

[bklein]

Never tried a penny. What will that tell me?

[Koala]

Never tried a penny. What will that tell me?

if copper good but gold is bad the delay setting will be too long.