Smudge said:
I have also been told by a technician at Tesoro that if you change the coil size, you ought to send in the detector to have it recalibrated to the new sized coil.
Smudge, that would be a correct suggestion from their technician, but you need to send in the detector as well as
all search coils you plan to use with it.
GibH said:
Not really feasible if you are using several different coils.
GibH, it is actually VERY feasible, especially if you are using any Tesoro models that you do not have control over the Ground Balance for every mode.
I this case, the post was started by 'shanegalang' who asked about using a larger-size coil oh his Cortes. I had a Cortes (3 of them, actually, when I was a dealer) here in Oregon and worked it in some Utah sites as well, and to compliment the stock coil I also tried a CleanSweep, a 10X12, and the thin, black 7" coil from a Shadow X2. Comparing performance of these coils to evaluate any usefulness of the Cortes' Target ID and depth performance I hunted two ghost towns, and now fewer than seven (7) older parks known to produce early silver coins.
Only the stock coil worked, except in one ghost towns and one park where it falsed a lit in the Discriminate mode, but the other coils, especially the larger coils, didn't work well anywhere. The 7" concentric worked about half-the-time. If I hunted in the All Metal mode I could use any coil without a problem because I had control over setting a functional Ground Balance.
That's not the case with the Discriminate mode with relies on a preset internal trimmer. With the larger coil and occasionally the 7" coil, the Disc. mode's GB references was too negative and the detector falsed when the coil was bobbed and lifted away from the ground, or if I swept over a depression or plugged hole.
For decades, Tesoro has encouraged anyone with a falsing problem when using one or more accessory coils to send the detector and all coil to then for calibration. Unless the search coil is defective and way out-of-spec, the 'recalibration' is no more than tweaking the GB trimmer, using each supplied search coil, so that all of the coils will work w/o falsing. All coils are needed due to the design approach Tesoro uses with their coils and they can vary a fair amount which will shift the circuitry performance and that means a Ground balance adjustment is called for.
Most of their models are 'turn-on-and-go' so it is important to send them all to the factory, or have a knowledgeable dealer or savvy user make the necessary GB adjustments. Most of the models with Disc. mode GB adjustment tied in with the manual All Metal mode setting can be set to work okay. Those with the preset Disc. mode GB, such as the Cortes, should be set for all coils a user plans to work on that model.
Monte
