Does anyone that buys a new coil do this?

This is mostly legacy information. Just like the Frequency myth.

Dave J. said:

The electronic circuit in the "box" is designed to expect a searchcoil having certain values of inductance and resistance and capacitance. With a certain type of connector wired in a certain way. Give it something different and it won't like it. Fortunately the wrong searchcoil usually won't fry a circuit.

Prior to the 1980's, many metal detector searchcoils were tuned with resonating capacitors in the searchcoil for both transmitter and receiver. These were designed to run at a particular frequency and the frequency of the transmit coil had to match that of the receiver coil to a high degree of precision, otherwise it threw the ground balance off. Two searchcoils tuned to the same frequency but from different manufacturers weren't necessarily interchangeable because of different inductance and capacitance values. In other words, back in the dark ages there was some basis for the urban mythology about frequency -- not much, but some.

Circuits got better. I don't think anyone uses resonated receivers nowadays, other than in a very few oldie but goodie legacy platforms. Tuned transmitters are still the norm in single-frequency machines, but in most models the tuning capacitor is on the PC board and the searchcoil itself can run over a fairly wide frequency range. Multiple frequency machines have been a staple commodity since 1991 proving that it's possible to operate a searchcoil over a wide frequency range if that's what it's designed to do.

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Give me a break.

Thanks for the explanation, I know I have used other coils and they performed as well as the stock coil with no problems.

NEVER ! That sounds like a manufacturer tech seaching for more revenue

When changing coils I just do a reset with my AT Pro. Then good to go.

No, because it is not necessary.

Modern detector designs are designed to allow multiple coils to be used on the same detector, for different applications or terrain conditions. The White's machines are a prime example of this.

A lot of the posts primarily referred to the transmit side. A more important aspect is the receive coil and its electrical parameters (inductance and capacitance). Target ID depends on the phase angle between the applied (transmit) field and the received signal. If you look at a phase response plot, showing phase angle versus frequency, you'll see a very non-linear part around the resonance frequency. For accurate target ID, you don't want a coil that would have the receive windings operating in this region. This can happen with a defective coil, or an improperly designed after market one, or one made for an earlier generation detector that operated at a different frequency.

This mainly is a concern when one is using a metal detector that has a preset ground balance from the factory with no external ground balance adjustment knob. When you buy a detector with a preset ground balance "new in the box" the coil is ground balanced to that unit at the factory. Later if you want to change to a different type or size coil it may not be operating at its peak with your preset ground balance that was done at the factory for the original coil.

I have a Troy Shadow X2 that has a preset ground balance(no external ground balance adjustment)but I can open it up and access an internal ground balance trim-pot and adjust it to any coil I can use on my X2.

Walknstik said:

This mainly is a concern when one is using a metal detector that has a preset ground balance from the factory with no external ground balance adjustment knob. When you buy a detector with a preset ground balance "new in the box" the coil is ground balanced to that unit at the factory. Later if you want to change to a different type or size coil it may not be operating at its peak with your preset ground balance that was done at the factory for the original coil.

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No not true.
I can put any search coil I have on my Fisher F2 (no external ground balance) do a factory reset on the unit and I am good to go.

do not need to open the unit to ground balance.

I think most of the newer detectors are made to use multiple coils without any of these problems

I would NOT own a machine that required this claimed type of maintenance. It would either be sold off or in the trash. And that's a fact !

And then there are Tesoros....

When I was looking to get the most out of a Golden uMax, I was advised by someone that works at Tesoro to send both the coil and the detector back to Tesoro so they could maximize the performance. I was also told that every detector/coil pairing leaving the factory was optimized to work with one another, so a pairing was not needed with the stock coil, and was really only advisable when you were going to put a coil on a detector and leave it on.

That was 3 years ago with non-digital gear. Take it for what it is worth. (I decided that the stock coil was pretty awesome and did not mate the detector with a cleansweep. By chance I later had a mechanical failure of a switch and asked to have the detector tuned to the coil while it was there - no one thought that it was an odd request and I got a note back saying that the work had been done and that it passed their tests.)

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TwistedT said:

No not true.
I can put any search coil I have on my Fisher F2 (no external ground balance) do a factory reset on the unit and I am good to go.

do not need to open the unit to ground balance.

I think most of the newer detectors are made to use multiple coils without any of these problems

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TwistedT really I should have explained a bit better. The type of detectors I was talking about are a bit older and don't have any type of reset unless you do it manually if you are able to by design. I learned to metal detect with a manual ground balance detector and thru the years I've become pretty picky with my ground balance setting. My Shadow X2 has an all-metal mode when you depress and hold down the pinpoint button and with my mild ground I can hear ground balance changes when I switch to different coils. Some people depending on their ground conditions may not really need to be concerned in making a change when swapping out different coils because the ground balance shift may only be slight...if it changes at all.?

Metal detectors work very similar to radio equipment. I the distant past, there was a knob or wheel on every radio, to tune in the different stations. Then, it became push buttons, now you a touchscreen... Digital tuning has been around for a while, and would think it's pretty standard for metal detectors as well. If you had to send in your machine, every time you wanted to use a different size coil, wouldn't that sort of change the calibration, so your stock, other sizes wouldn't work as well? You'd be stuck with that one coil, until you sent it back. Pretty inconvenient, costly, time consuming. Don't thing the factory would want to keep providing the service, for every unit the sell. The user would rather be hunting, then sending the machine back and forth.

Now, I do believe that any machine, can be better tuned, for the type of ground it's going to be used (regional). There is a big enough difference in the environment for some, that a little tweaking could help get better function. For most of us, we might only get another inch depth, or a little better stability.

coil change

ground balance your unit it will be fine

oneton said:

ground balance your unit it will be fine

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Maybe ... but Maybe Not!​

You dredged up an old post from 4½ years ago. For fun I read through the original post and the replies. Most responders were wrong. 'Walkinstik' was the most correct as it related to the brand and models he referenced.

Back in the day when we got GB for recreational detectors, about '74/'75 and for a decade or so after, most avid detectorists understood Ground Balance and knew how to make a functional GB adjustment. Since then we have had more newcomers to this outdoor sport who are into modern electronic stuff being 'simple' and 'pre-set' or 'already adjusted so they don't have to', and, honestly, most folks in the hobby today don't know what Ground Balance is, what it does or doesn't do, or have any idea how it works in a motion-based Discriminate mode.

Most detectors offered today rely on a 'fixed' GB, or a partially 'fixed' GB for some modes and an Automated or manual GB (or both) that are only/mostly functional in the Threshold-based All Metal mode only. The adjustment doesn't carry over to the Discriminate mode.

And with the move to more digitally-designed, software-controlled detectors, there is no external GB control, nor an internal GB trimmer as it is all done "in software." And quite often I find it not to be all that functional compared with a good, manually-controlled detector.

What detector makes and models do YOU own and use, and do YOU have full control of the Ground Balance?

One of my best friends and a long-time detecting buddy is a very, very dedicated ghost town hunter. I sold her a detector in May of '86 and she still uses it or one of four others she inherited from her parent's passing, or has purchased. All of them were made between '86 and '98. Debbie hunts very high-trash old sites that abound in nails and other iron discards. She works smaller-size search coils slowly and methodically, and has fund a lot more old coins than many of the people I know in this sport.

She can't describe Discrimination or explain how it works. She hasn't got a clue about the shape of the EMF around a Concentric or Double-D coil ... and doesn't know the difference between those two coil winding configurations. You wouldn't get a good answer if you asked her to describe the scale or range of typical target conductivities, or be able to tell you the difference in the effect of similar size and shaped ferrous and non-ferrous targets on an EMF.

Recovery Speed, Separation and many other often used terms she also doesn't understand, and I can guarantee you that Ground Balance knowledge, understanding, or ability to make an adjustment is just about the farthest thing from her mind.

She's a female, yes, but she's no different that probably 90% or more of the people out there who have a metal detector. They haven't got a clue about what it is, how it works and why it works, and what the different terms and adjustments are, or how they might effect the performance of a metal detector.

I guess as long as people use what they have, find stuff and have 'fun' then all is well being an 'average' hobbyist.

Monte

coils

As long as as i go with the same size and type coil i dont have any problems with GB.Its when i change sizes of the coils then i find out i have to have it tuned to the detector which i do myself anyway.