GA1dad said:
Did some air testing this afternoon and established that I have definitely been swinging too slow.
Possibly, what that depends on what your definition is of
'too slow.' It's possible, but I'd say that wasn't the reason for poor performance and not getting a good-target response from a 6" silver dime. Tesoro's are designed with what was generally described as a 2-Filter or Double-Derivative type circuitry, and at the time of their introduction in July of '83 of their first popular motion-Disc. model, the Inca, there was really only one other comparable model on the market from Fisher, introduced the year before. Almost all other motion-based Discriminators used what was referred to as a 4-Filter circuitry. The main differences were that a 4-Filter design, such as a White's 6000 or XLT or the Teknetics 8500 or 9000 for example, used a fast-motion circuitry..
Those
required a
very brisk sweep speed to a moderate to faster sweep by the time of the XLT. They handled higher mineralization better but needed a fast sweep speed. They were usually heavier detectors and the required fast sweep was also very fatiguing. Then along came the 2-Filter types, like your Cibola, and
by-design they
needed to use a slower sweep speed. By 'slower' I mean they could better process the target signal and provide a quicker-response and faster recovery time, and achieve that performance at a slower sweep. Why" Because due to the circuitry design, if you sweep a coil too quickly, you will force in more ground signal and the detector can't process out the ground signal to pass along the target signal. It needs that slower sweep to allow the processing time to handle the ground mineral signal first.
The more mineralized the ground, the more important it is to use a slow-and-methodical sweep speed. If the ground is a mix of black sand or pea gravel or small rocks, that makes it all the more difficult for a 2-Filter type detector to handle it easily. And by
slowly and methodically, I do not mean a sluggish crawl of the search coil. Just a comfortable slow-motion sweep of about 2 seconds for a complete left-to-right sweep, and then 2 more seconds to sweep back the other way, going about 3' to 4' each direction.
GA1dad said:
Got plenty deep when swinging coins past the coil very briskly,,, but not deep at all with a typical slow, methodical speed.
In an "air test" with the Tesoro or most of the makes and models in use today that use a pretty quick auto-retune speed, you will almost always notice an increase in "air depth" as the sample target is moved past the coil's center axis with a faster sweeping motion . However, all the detector is doing with the search coil stationary is responding to the accepted metal target sample, but it isn't also being fed a ground signal to have to filter out.
If you have other detectors that
do get the buried silver dime, such as your Tek. T2
[size=small](an interesting filtering system)[/size] and White's MXT [size=small]
(which has a 3-Filter circuitry design which does allow a brisker sweep speed)[/size] using comparable settings then there are other considerations, such as:
• The search coil size and type used on all models
• Detector control settings.
I noticed you mentioned you have a Cibola that:
► "
I have a Cibola that I purchased used last year."... A good general purpose model, so that's good if properly calibrated [size=small]
(aka GB'e[/size]d)
► "
I performed the ground balance mod, and the GB process works as it should, but it still will not sound off on the 6" dime".... So, you did the Ground Balance modification on the Cibola yourself, or did it come already modified?
• And you're sure it works Okay?
• Did you check the modification in both the Threshold-based All Metal mode as well as the silent-search Discriminate mode?
• Did you double check the GB setting in the Discriminate mode?
• Do you have a too-positive GB setting? That can cause some high-conductive target loss if mis-adjusted.
► "
I super-tuned it via Keith Southern's video, and it still will not sound off on the 6" dime." ... I haven't watched Keith's video but I have seen others, and one guy with a Vaquero does things different that can effect performance. A few years before Tesoro started using the term 'Super-Tuning' I was using and showing that method which I had named 'Hyper-Tuning' simply because it was enhancing the received signal from weak to on-the-edge and louder. I always run a Tesoro w/ED-120 Disc at the minimum Disc. setting. With the Cibola and Vaquero, which use an ED-165ish Disc. circuitry, I generally increase the Discrimination to
just barely reject common iron nails. I also run the Sensitivity level as high as possible w/o static / noise. I keep it at maximum or reduce it,
if necessary, just to the point where I gain stability.
In the All Metal or Pinpoint mode I make sure I have the Threshold level set for a 'proper' slight audio hum. Then, if I want to 'Hyper-Tune' the unit, I increase the Threshold to maximum of as close to full Threshold loudness as possible. That's basically going to increase and saturate the audio response from weaker, deeper targets , but can also saturate 'noise' and at times it can get a little bothersome. It was helpful, at times, when Coin Hunting cleaner areas with deeper-located targets. Not really helpful on shallow to typical-depth targets, and it also makes the Pinpoint function useless.
To be honest, and I have been using Tesoro's all the time, along with my other detector outfit, since July of '83., I hardly ever use any Hyper-Tuning or 'Super-Tuning' because it really isn't needed with the more powerful models compared with their earlier models that were definitely wimpier. My Bandido II µMAX and the Silver Sabre µMAX, as well as Cibola and Vaquero are all some of the better performance models that Tesoro ever made. So, if it is a silver dime laying relatively flat-to-the-coil, I wouldn't bother digging it up. If your MXT and T2 are hitting it well, but the modified Cibola isn't ... then the problem lies elsewhere. Possibly in the circuitry or, quite possibly, in the modification or tuning procedure.
GA1dad said:
Second question,,,,,, when ground balancing for air tests,, should I center the 10 turn ground balance pot 5 turns from either direction?
No. For one thing, the best setting is going to be one that would otherwise be in harmony with the ground mineral environment you plan to search it. Also, you want to make sure that your Ground Balance modification was done so as not to mess up the manual GB effect on the silent-search Discriminate mode. That is where I have seen some cases of folks doing a GB modification to a pre-set GB unit and things have gone wrong.
Do you still have the internal GB trimmer on the circuit board, or did you remove it when you did the mod.? If you have a chance,
and I'm up all sorts of hours, give me a call and I'd be glad to discuss the performance with you. Contact number is in my signature below.
Monte
