Omega air test.

[John in Nawth Carolina]

What kind of distance should one get with the Omega on an air test quarter? I'm thinking mine may be defective or I have some interference.

 

[TerraDigger]

Here are two tests with concentric coil. One is mine, the other is Monte's (one of the most experienced users @ FMall)

Monte:
All Metal Mode - GC 82 - Sens 65
ID # to 8"......Audio Signal to 9.5-10"
Disc Mode - GC 82 - Sens 65
ID # to 7-7.5.....Audio Signal to 10"


TerraDigger
All Metal Mode - GC 82 - Sens 65
ID # to 7"......Audio Signal to 11.5-12""
Disc Mode - GC 82 - Sens 65
ID # to 10".....Audio Signal to 10"

You will see that Monte gets 1" more ID # depth in all metal. However my machine exceeds his on audio depth in disc mode. Also my machine will register a ID # as soon as the ever so slightest audio signal is generated. Quite a large difference in the depth reading of ID #'s in disc mode.
There are variances in machines of same model. This is a common phenomena with all mfg's. So I would only be concerned if you have readings that are significantly different than these. If you are testing indoors it is very possible that EMI is affecting your readings. Even if you don't hear EMI chatter in the audio threshold. Test unit outdoors in a area you think is as free from electrical emanations as possibe (rural). And if have a cell phone with you, turn it off. Make sure that when testing in all metal (autotune mode) that your set to barely perceptible audio threshold. Usually threshold kicks in at around 69 sensitivity setting in autotune mode.
One thing I found is that when I lower my GC to 24 doing indoor testing, my machine falses considerably less than GC 82.

Hope this helps

 

[John in Nawth Carolina]

Thanks! That's what I was looking for.