One of the biggest 'problems' I have seen sine we first had Ground Balance burst on the scene about forty years ago has been a number of factors with how well individuals learned what it was/is and how to manually adjust a proper GB, and how the different Discrimination circuitry's worked with an All Metal mode Ground Balance, or with the GB function for the motion-based Discriminate modes.
But even more complexing is how the different design engineers have made their determinations for various makes and models. Some have a separate GB adjustments for the All Metal mode and Discriminate mode. Some models have an automated GB. Some have an internally set GB. Some blend these two in one model with a manual and/or automated GB for All Metal and a preset GB for the Discriminate mode. Some might use a ground tracking circuitry that functions continuously or just updates as needed [size=small](toggle or Ground Grab),[/size] and others have designed a pre-determined GB in the circuitry and there is no internal trimmer to tinker with.
In some designs there is a pronounced GB 'offset' between the two modes [size=small](All Metal and Discriminate)[/size] where the Disc. mode GB varies with the manual GB adjustment, but it is already off-set quite a bit positive from the manual setting used in the All Metal mode adjustment. And, it can get worse when we encounter a design where the variable Discriminate mode adjustment also changes the GB! That problem was more noticeable on some Tesoro models than other brands.
Ground Balance and Discrimination functions are all part of the different reasons I use the testing I do to evaluate different detectors for performance versatility, and I have done that for a long time.
smokey63 said:
My next question for everyone is, since the 5" and 11" coils did not perform well in Monte's test with the ETPro that come with the stock 8" coil.
Do the ETPro's need to be FACTORY retuned with optional coils for optimal performance?
My
first question [size=small](I asked myself)[/size] was, HOW was the GB setting determined, as well as was this particular model 'calibrated' with the coil it was shipped with, or do they use a different method of calibration that
might better handle an assortment of search coils? Do they calibrate each individual detector with the coil it is to be packaged with? I know many/most manufacturers
used to, but in this wonderful 'digital' age, maybe they do things differently? They didn't appear to be using an auto-tracking circuit because I checked that, too, using a few varied ground mineral samples to see if it affected the Disc. mode's performance.
With
most Tesoro models, where the Disc. mode's GB is tied in with the All Metal mode's GB adjustment, if they are preset internally, then they can tweak the GB trimmer to function okay with all the coils a person has. The trade-off, however, with a fixed GB model, is that it means some coil/detector combinations might be GB'ed close to spot-on, while other coils would have a more positive GB, and it's possible that could be
too positive and the results would be like those I had.
The
second thing I wondered was how many other people, who have a Euro-Tek Pro, have tried an assortment of search coils [size=small](or just the stock coil)[/size] and also used samples to include a big silver half or silver dollar? If anyone has, what were the results they got? [size=small](
Anyone can e-mail me, if you don't want to post, as I am curious .... monte@stinkwaterwells.com)[/size]
smokey63 said:
Man, they should have put a manual GB on this thang!
Maybe, but I would bet most consumers still wouldn't know if the GB was tied only to the All Metal/Pinpoint mode, the Discriminate mode, or both. I checked all four search coils as best I could using a very mineralized rock with a Ground Phase of 84 to 91 on the G2. In the All Metal Pinpoint 'mode', I couldn't tell any noteworthy difference for a GB setting with the Euro-Tek Pro as they each displayed a very similar response from the rock.
I believe any internal GB trimmer in the Euro-Tek [size=small](and I am simply guessing based upon my sampling because I haven't opened the control housing)[/size] is only tied in with the Discriminate mode. If so, then I would also best guess that many users wouldn't be able to establish a 'proper' functional Ground Balance because the Discriminate mode is 'silent search.' If I were to tinker with it, then I would use all three search coils I have [size=small](5" DD, 8" and 11" DD)[/size], then use some intense bad-ground samples, and 'Power Balance' the Euro-Tek Pro in the Discriminate mode so that all three coils were functional.
If done right, and if the circuitry was totally functional, I would best guess that I would get a response from the Silver Dollar and half and other coins, and there's even a chance that those very high conductors might just happen to produce slightly lower and more accurate VDI numeric read-outs. Now, that's only a 'best guess' on my part, and only if there is an internal GB trimmer, and if it is functional with the Disc. mode's GB reference.
My Euro-Tek Pro works fine with the stock 8" coil and someone might enjoy it at the killer price I am selling it for. If nobody buys it then I might open it up and see if I can enhance the Disc. mode's performance with the 5" and 11" coils. Especially the 5" coil because I figure the Euro-Tek Pro's strength is in working in trashier sites and closer to metal structures. While the recovery rate isn't fast enough to handle my Nail Board Performance Test, the quickness of response is satisfying [size=small](as are all the Teknetics Greek series models)[/size] for a lot of moderate iron trash sites I would use it at.
Still, no perfect detector out there, but there are a fair number of detectors in the
'reasonably worthy performer' category.
Monte
Have to read it again a few times to absorb it! good job!!
You can look up this mod on the net if you wish.