Coil " re-tuning"..question

[reddirtfisher]

I certainly don't pretend to know everything about detectors so here goes another question for you more experienced users. I have always wondered something. What exactly does " re-tuning " the coil during a repair do for the performance and use of the metal detector? I have spoken to the repair techs several times in the past but always forgot to ask them about it. Does anyone know? Thanks. RDF

 

[jabbo]

I think Tesoro ground balances the detector using that coil in their standard GB method. I have 5 coils for my Golden. I can use any coil and the detector GB is good with any of the coils.

 

[Hombre]

reddirt,

If you have a manual ground balanced Tesoro, you can do the 'tuning' yourself, no need to send it in. Just ground balance it, simple as that, hope that clears it up for ya.

 

[BarberBill]

Generally, retuning refers to fine tuning a Tesoro preset detector to the optimum ground balance (factory specs) for any different sized coil other than the one it was originally tuned to. Much of the time the preset detectors work okay with any of the other size coils, but in mineralized ground and/or to get OPTIMUM performance and depth a retune may be necessary. I have several preset models that work okay with most of the different coils, but haven't tested in any way to see if that could be improved as they work well enough I haven't felt the need, plus I have several manual ground balance models that I can use if needed. As an example of what I'm saying, one detector chatters, even on fairly mild ground, when the 10X12 spider is mounted. If I wanted to use that combination most of the time, I would send that detector and the coil in to be tuned, but I don't use that coil a lot and when I do, it's on one of the manual ground detectors where it performs with no problems.
BB

 

[reddirtfisher]

Thanks guys, There's an old saying that goes, " Ya never know until ya ask". Thanks for the replies and ,..yes,.. that does help me understand it better. All my units are pre-set GB and they work well in my Oklahoma / Texas dirt where I hunt.

 

[Hombre]

Thanks guys, There's an old saying that goes, " Ya never know until ya ask". Thanks for the replies and ,..yes,.. that does help me understand it better. All my units are pre-set GB and they work well in my Oklahoma / Texas dirt where I hunt.

Depending on what pre-set GB models that you have in your collection ..... you can still optimise your ground balance. I would just put the detector in all-metal and check on how good of a setting from the factory you have. The threshold should hold unwaiveringly when bobing the coil from about 6" to 8" to within 1" above a clean piece of ground. This is a true 'spot on' GB if the threshold does'nt change when moving coil up and down in all-metal mode and have a Tesoro with a true threshold all-metal mode. Silver

 

[machineman]

This is interesting. I was having trouble with my Outlaw and sent it in for inspection. I waited a few days and then sent a Allcav a PM asking about it. He responded "Well, I know this wont sound very good but the coil is out of tune. This will put an extra 12-17 days on the repair." As we all should know the Outlaw is a manual GB detector.

 

[tabman]

This is interesting. I was having trouble with my Outlaw and sent it in for inspection. I waited a few days and then sent a Allcav a PM asking about it. He responded "Well, I know this wont sound very good but the coil is out of tune. This will put an extra 12-17 days on the repair." As we all should know the Outlaw is a manual GB detector.

Right! A coil 'out of tune' and 'ground balancing' are two separate issues from what I have gathered. I could be wrong. Keep in mind, even a detector without a exterior ground balance knob has an internal adjustment pot. From what I have been told, the coil is tuned by adjusting the lengths of wire inside the coil. A very small about of change in the length of the coil wire makes a big difference.

You sometimes get a coil that works better than other coils on a detector that has a ground balance even though it's the same coil size and type.

tabman

 

[Rick in Pa]

The detector control box is like a radio transmitter and receiver and the coil is the antenna. If the coil (antenna) is not tuned to the frequency of the radio (control box) then the output power is greatly reduced, which would give less depth to detector. It is why techs try to get a low SWR reading on CB or HAM radio systems.

 

[Monte]

Search coils can be 'tuned' within certain specifications. By design, some manufacturers have a little "sloppier" tuning allowances while other coils follow a much tighter or more controlled set of 'specs.' In the internal winding alignments is out-of-whack, the coil can easily fail to perform well, or at all. The same applies to failure with any internal electronic components in the search coil. Dropping a search coil on a hard surface, smacking it hard against a tree or rock, or even some cases of temperature extremes can cause misalignment's or make a coil fail.

So, each manufacturer has their own design criteria to follow in their coil design allowances in order for them to work with the manufacturers detector circuitry design and operating frequencies.

Most manufacturers check a detector and coil combo and make sure they ought to be compatible before shipping, and then they are off to get boxed up as a checked-and-tuned pair (detector and coil). In this case, the detector itself has to pass the test to make sure it functions properly, and is then checked with the assigned search coil. If it is a factory preset GB model, then they set the GB to their desired spec with that coil to work in their determined level of iron mineralization.

Unfortunately, we face several challenges with this type of design, such as the following.:

a.. We trust that the detector and coil are each functioning within 'spec.'
b.. We trust that the factory-set Ground Balance will provide good functional performance in BOTH the All Metal mode AND Discriminate mode.
c.. We have to hope that, by design, the Disc. and All Metal modes function well with a similar GB setting.
d.. We also hope the manufacturer has provided and internal GB trimmer that a savvy detectorist can easily adjust to tweak the detector for peak performance in radically different ground than what the factory set-up instructions will handle.

The next thing that we could benefit from is having an assortment of search coils that share very 'tight specs' which lets them be highly functional on an assortment of metal detectors designed to operate withing their design criteria. With some makes of coils, they see to have a little more 'slop' in their design and at times that can mean too much variance from a tight design specification. Due to the variables in detector and coil design, and having used a LOT of detectors in my 48 years of detecting, and being a multi-line dealer most of the time since '77, I have found the following to be true.

1.. With some brands, I can try maybe 10 search coils on the same detector, even the same size coil, and I am able to set the Ground Balance and have the detector work. However, I might notice a pronounced difference in the perceived performance between one or more search coils of similar size and type. They work, and they are not noisy or erratic, but some might seem a bit 'hotter' and others are perhaps a little weaker performing.

2.. With some brands, they have very tight specifications for the search coils as well as specific operating frequency that is crystal controlled or otherwise established at a tight setting. Equally, their search coils have a very rigid specification design. If I switch an assortment of search coils around I might have one of two things happen. They all work, work well, and are not noisy, or there might be a coil or two that doesn't seem to perform well and the operation is unstable. Usually, this is a case where the coil is just "out-of-spec" and even adjusting the GB will not result in proper performance.

In the end, regardless of the brand of detector and coil we choose to use, we need to make sure they are a quality-built product and then learn them and know their strengths and weaknesses. There is no such thing as a 'perfect' detector so we have to appreciate each detector we chose to use for its abilities for our needs, then learn and know how to get the most out of it. When it comes to Tesoro models, I have reached the following conclusion, all based upon the facts that I most often hunt in moderate-high to very-high iron mineralized sites.

I know that:

A.. I do not like, and haven't had good performance in a variety of ground environments with, the Cort

 

[reddirtfisher]

Wow Thanks for taking the time to explain this ! My Silver Sabre uMax and my Golden were both serviced at the factory in the past. I only have one other coil,...a 4 inch which doesn't seem to get enough depth,...maybe 3 - 4 inches max. I appreciate everyone's comments,...not just Monte's. I love this hobby. It takes my mind off my real life problems. Best Wishes to all, RDF

 

[allcav]

Re-tuning a Tesoro coil is this:
On Tesoro coils, except a pulse, there is two windings inside the coil. A Transmit, and a Receive. In order for the for the receive not to pick up the transmit, we tune it with a piece of wire from to the other. When this wire shifts or moves, it is no longer in tune. Therefore, we have to re-tune the coil.

 

[Hombre]

Re-tuning a Tesoro coil is this:
On Tesoro coils, except a pulse, there is two windings inside the coil. A Transmit, and a Receive. In order for the for the receive not to pick up the transmit, we tune it with a piece of wire from to the other. When this wire shifts or moves, it is no longer in tune. Therefore, we have to re-tune the coil.

allcav........you guys can 'tune' a coil.......but you can't tuna fish

 

[allcav]

If I could tuna fish to jump right in the bag, I wouldn't need to work!