White's TDI - TDI Pro - TDI SL

I would like some opinions and explanation on the differences between the TDI, TDI Pro, and TDI SL.
I am thinking about trying one out for turf coin hunting but have never had a PI.
I have a couple different parks I hunt that have high minerization and very deep coins.
The old coin layer starts at 7" but I have not been able to punch past 10" with my CTX and have only did that a few times.
I am mostly hunting for high conductors. Copper and silver coins.
Hoping to get 11-12 inches on a dime to see if there are coins sitting just out of reach of my CTX. Will the TDI get me there?
Coil recommendations And leads to a used detector also appreciated.
Thanks,
Bryan

Bryan I have a TDI/sl and they are not as deep as a TDI pro due to battery power. However I think the sl is less noisy? as the larger box pro. When u turn on the ground bal,which makes it a discriminator type detector u lose a lot of depth,but u can knock out some trash as knob if from 1 to 10, The more grn bal u give it the less depth,however u have a disc type detector,when grn bal is on and can cherry pick the ground. I noticed that air test without grn bal on u get a coin at say 12in or so and when u turn on the grn bal it knocks the depth (air test) down to say 8in -when getting rid of foil and pulltabs. So there is a trade off of sorts. I have the stock coil and a 7.5in and a 14in I believe it is. U can use minelab coils so there is a bunch of coil sizes u may use for different applications from coin hunting to cache hunting which I do a lot. shortribs.

I was in the same type of situation where I was getting coins in the 8 to 10 in range with my CTX in my soil. They were iffy type signals so I knew that 10 in was about the max depth I could get so I bought a CZ 6a and sent it to Tom who tuned it to a dime at 11.9in. First time out with it I hit a SLQ with the 10 in coil at every bit of 12 in. Was shocked at how deep it was getting. Since then have dug several wheat pennies and dimes in the 10 to 12 in range. Have dug several deep nails also but at least it's getting me to that depth.

Higher conductors,,,,not pulse inductive units' strongsuit,,,,rather low(er) conductors.

I was involved in the testing and development of the original TDI. Without opening up a can of worms I would never use any Pulse detector with a GB feature unless I'm hunting in difficult soil for Civil War Relics or on a salt water beach looking for gold. Just remember this. Think opposite of what you have leaned about VLF detectors. The detector will respond to high conductors better when the ground balances over 7. Under 7 you start to loose your depth advantage! This I know from over a year of field testing prior to it's release. The SL has less power (a 14 volt battery pack can be purchased from a third party vendor) but works the same as the other two and is lighter for sure. Good luck!

The main difference between the TDI Pro and TDI regular is the ground balance controls. The Pro had a fine and course GB setting for getting it more precise. Truthfully, with the DD coils this is not much of a problem. With the mono coils it can be a little more of a benefit to have the fine adjustments because a little movement in the control goes a long way with them. The SL version is what I call the neutered version of the TDI. It was sort of like what they did with the F75 when they did the DST mods to it; made it more stable but at the cost of some depth unless you rig a different battery system to it.

The TDI will get you to the coins in the depth range you are wanting. But I would venture to say that 11-12 inches is about tops on what you are going to get out of a TDI on a dime with the stock coil size range. As TNSS said, where you really see the big boost in depth is on low conductors. You will be able to pick up a nickel deeper than any machine you've probably had in your hands. The same goes for gold jewelry; which is one of the reasons why I have the TDI. I have several after market coils for my TDI; including some of those $400 Nugget Finder coils and CoilTeks in sizes from 8x14 up to 16 inches round. My favorite coil by far is the 8x14 Nugget Finder mono. It's light weight and goes deeper than the stock coil by a pretty good bit, and is an all around good coil. But even it doesn't get you much past 12 inches on high conductor coins. Low conductors though...look out.

The Minelab GP and GPX series are more geared towards what you are wanting to do. They will for sure get you the depth you are looking for on high conductors but at the cost of a heavy battery pack and wires. One option that a lot of guys are going to, to get away from the wires, is a wireless headphone set and then mounting the battery pack onto the side of the control box. They are getting those Worx control box covers that have the battery compartment built onto the side and using a short aftermarket power cord. This eliminates the whole being tangled in wires thing...which was always my #1 gripe of those machines. On a side note...the GPX machines are cheaper than a Minelab CTX 3030 now.

My TDI Beige Prototype had a tone adjustment instead of the high/low select switch. Wish that stayed!

Thanks everyone. Sounds like the TDI improving my situation will be marginal for high conductors.
If I can find one priced right I might test one anyway and see what it does on my ground.
My CTX runs single digit to low teen recommended sensitivity so I have to run manual to get any depth at all out of it.

Welgund I tried the CZ 5 twice. One was a Tom Tuned 12.1 detector. Dimes just past 6" read as nails.

Daniel the reason I was thinking about the TDI instead of the GPX is the TDIs ability to have kind of a form of discrimination.
My hunting is done in City Parks so that is very important.
Like I said I have never had a PI detector so I could be missing something here.
Does the GPX or even the SDC2300 have any way to tell a nail from a coin, or low vs high conductors?
Thanks
Bryan

Bryan,

Yes the GPX has both actually. If you run the DD coils you can also have it breakup the tone over iron with the GPX. In that way, the GPX is actually a 2 tone unit. You will have the breakup on iron, then a high tone for foil through pull tab range conductors, and then a low tone from just beyond pull tab through silver dollar. On the higher end GPX models you can invert the signal sound and make it the opposite, which is what most people are accustomed to with a VLF machine with tone ID....i.e. low tone for low conductors and high tone for high conductors. It never really bothered me though.

Keep in mind that the TDI doesn't have a discrimination either. Some people will set the GB point to a certain points (it changes with the micro second range...if you run it at 10 micro seconds, usually this transition will take place at a GB position of around 4....normally the machine will balance at around 7.5 to 8 with that micro second setting), and then switch the machine into high conductive when coin hunting. All it really does, is change the break point over iron which is actually still coming in over on the low conductive audio channel...but because you have it swapped off, you can't hear it. In theory it works okay. In reality, you lose a bunch of depth with it and you will not be able to get to your depth range goal. You will do good to get halfway to it, and I dare say that would be a liberal estimate of it...it loses quite a bit of depth setting them that way. The audio channels on the TDI work much the same as the GPX...it is a two tone unit which gives a high tone for foil through approx pull tabs and then a low tone for just beyond pull tabs through silver.

I currently have the TDI and don't have a GPX any more but for what I plan on doing with it, it will suite me just fine. I have very little $ in this TDI and a good coil selection for it; and if I ruin it on the beach hunting with it, it wont hurt as bad as ruining a GPX. I have approx $275 in my TDI itself with the stock coil, and then found the Nugget Finder coils for sale used and got those at a good price.

Thanks Daniel!
I obviously have a lot to learn. I'll start cranking up my research on the topic and start keeping my eyes peeled for some good deals.
Maybe I can find a dirt cheep TDI like you to get my feet wet in the PI world. GPX sounds like the ultimate way to go though.
Bryan

Bryan,

I don't think the learning curve was that hard. I'm actually struggling more with the CTX 3030 than I did with any of the pulse machines.

The deals on the TDIs can be found if you keep a sharp eye out. You said your ground was bad enough that the FBS machines want to run single digits to low teens. That's almost exactly the same as what the CTX wants to do for me around here. And I've run into the same as you said with the CZ machines. I've never had a NASA Tom certified model but have had several CZs over the years and in this soil, once a coin gets past a certain depth, they read as iron. It's very frustrating to say the least. I envy the guys that live in good soils; I can watch the YouTube videos of them pulling coins 9-11 inches deep and the coins sound awesome on the machines. Very clear cut dig me signals.

Bryan I may add that the TDI is the only pulse unit that can effectively dig High coins and not alot of orany trash..maybe even less than a VLF..

Hersa vid I did for coin setup.

[www.youtube.com]

watch that video and see if a light goes off in your head?

Keith

“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla

Bryan....not sure if you ever saw this article.

Steve H article on TDI coin setttings

Yes, good stuff guys! Thanks.
I'm going to be on the lookout for a good priced TDI and give it a shot.
Worse case scenario I can use it for nugget hunting if It doesn't produce deep silver in the park.

Keith did the custom battery improve depth on the SL?
if so where can you get one?

Bryan

It did Bryan....But still didn't seem quiet as hot as a Big Box...

even better is get a Big Box and send it to Reg for quietening Mod.

Also on a big box I seem to be able to get a little better trash rejection in the ground bal manipulation..there's a an on off switch in the potentiometer and when you get around two it starts to click into the switching device to turn the ground balance on and off..on a big box the switch is separate to turn the GB on or off through a toggle.. and there seems to be a slight little more range below 2.or right around 2 at least to me....I know it works fine it just seems those switched Pots seems to cram some range up int eh bottom end..if I would of kept a SL I would of wired a regular pot in and mounted a toggle switch....

But mainly me just being anal..LOL!!

Keith

“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla

Sadly, I don't think Reg is doing any more modifications.

I think Reg may have given the instruction to another guy who is doing them..

I sent mine to that guy ..

Ill see if i can locate his email..
Here It is

"Keith

Here is the pricing schedule for the TDI modifications:

Basic noise reduction : $120

Basic noise reduction + op amp replacement: $125

All prices include insured USPS return shipping.

Prepay with PayPal, money order, or check. PayPal is preferred.


Turn around time is 1 to 2 days.



The basic noise reduction greatly decreases the annoying 'warble'
and has been the most popular mod. Adding the op-amp replacement
decreases the overall noise and increases sensitivity just slightly.
If you have any questions please don't hesitate to email or call.
We only need the control box. So, it should be removed from the shaft.
Keep the 4 screws also. DO NOT SEND any batteries. We have those
to use when we check out and calibrate the detector. You can send
your unit to the address below.

Paul M."

if anyone wants his contact info P.M.me.


Keith

“I don't care that they stole my idea . . I care that they don't have any of their own”
-Nikola Tesla



Edited 1 time(s). Last edit at 01/13/2017 04:22AM by Keith Southern.

Hey Guy's here's some things you should know and Try.

After doing side by side tests between the TDI Pro and the TDI SL I found that turning the GB off on the pro adds depth but by turning the GB off on the SL actually takes away depth,

Try this,,,, Grab a US Quarter and Air Test the SL with the GB off, the Gain flat out with the conductivity switch set to all and make a note of the depth,

Now try the same with the Delay on 10 with the gain maxed out and the GB set to 7, Now wave the Quarter in front of the coil and again it will read around the 12 inch mark,

Now do this bring the coin up to the coil so it overloads and then try sweeping the coin at around the 15 inch mark NOTE that it will only signal once because the SL has a smoothing effect when the GB is turned on and it sort off ground balances the coin out to a degree so you loose about 3 inches when doing air tests with the SL,

Let me explain more ??

No doubt that you have all seen that Great Video on YT on the Beach where the Gentleman turns the GB off on his TDI Pro and the Pro smooths out the ground noise from the beach and remains quiet unless he raises or lowers the coil even closer but as long as he maintains a uniform height the Pro behaves,

Well The TDI SL does that but only with the GB on,, NOT when it is turned off, Now before anyone panics, So please humour me for a little while longer, Ok?

Now this worried me at first thinking that I was loosing that 3 inches off the depth, The truth is you are NOT because unlike Air Testing as you sweep the coil the machine is running flat out and it is BUSY Focusing/smoothing out the slight variation in the Ground and by doing that it Still sees the Quarter at 15" +/- give or take.

NOTE:- There is NO depth boost on the TDI SL when you turn off the GB, That only works on the Pro and the smoothing effect on works on the Pro with the GB OFF and on the SL The Smooth / Boost effect only works with the GB ON, Also on Small Targets there is No Difference in Depth between the TDI Pro and the TDI SL and on Large Targets BOTH machines have the power to see Large Targets up to 5 or 6 feet in the Ground, On Larger Targets The Pro is Deeper, OK.

Hope this helps and remember that overload trick when you are Air Testing the TDI SL because it will smooth the target by about 3 inches with the GB on and the Pro does it with the GB OFF ok.

Good luck and happy testing,,,, John

Keith...sent you a PM

I use a TDI Pro,dont use it for coinshooting though,just run in in straight PI mode for deep large targets.



Edited 1 time(s). Last edit at 01/13/2017 07:50PM by Junk and Disorderly.