Need a little help on this one

Ok, let me try to explain what I am experiencing in my back yard test bed with the Omega. In my back yard I have a US clad quarter buried at a modest depth of six inches. My F-75 (not LTD), F-70 and my CZ3D have no problem detecting this coin and all three can actually detect the coin with their coils raised another 4 or 5 inches above the ground. The Omega on the other hand struggles to detect the quarter with the standard coil installed. From what I have read and also witnessed on video a 6" deep quarter should be no challenge for the Omega. Not wanting to believe what I was seeing I continued to try sweeping at different angles and such and that is when I discovered that when I raise the coil approximately 3 inches or more off the ground the Omega starts to give me a nice clean repeatable high tone and correct target ID but when I lower the coil to the ground and sweep, the Omega nulls or goes silent. My fist thought was there must be some sore of silent masking going on so I moved over to another location where I have a 6" US clad dime buried only to discover the exact same thing. With the coil being swept over the dime in a scrubbing fashion "no joy"; however, with the coil raised a few inches above the ground the Omega detects the coin with a clean repeatable high tone.
Now, when I install the 11" DD coil on the Omega it is transformed into a totally different machine. With the larger coil the Omega makes short work of the 6" quarter, and hits 6" dime with plenty room to spare. Out of curiosity I installed the Omega's coil on my Gamma to see if I could reproduce what I was experiencing with the Omega. With the Omega's 10" elliptical coil installed on the Gamma I was able to reproduce the exact same problem.

Bad coil maybe? I know there are some pretty smart people that frequent this forum and I would really like to hear your opinion because I am somewhat baffled.

Thanks,
Leo



Edited 1 time(s). Last edit at 01/15/2010 12:31PM by Leo234.

Failed shield-paint on the coil. Bad coil. Without the shield-paint (which is internal).......the coil will be 'reactive' to the dirt. If you cut-n-paste your above post......and send it (and coil) to Fisher.......they should replace it. Quality control would also reevaluate their Mfr process. . . should a problem be exposed.

Thanks Tom,

The problem has already been reported and First Texas replaced the coil. Unfortunately, I have not been able to test the new coil becasue the test bed is covered with several inches of snow. Once the snow melts and I get a chance to test the new coil I will post an update. Despite the coil being replaced I still needed an explanation for future reference.

Leo