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Author Topic: Some in the ground tests with the Teknetics T2 Ltd  (Read 10497 times)
Rob Two Spades
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« on: April 07, 2011, 12:15:58 PM »

This test is copied from Thomas Dankowski Open Forum, I thought it useful to T2 owners.
I tried the same test with a 5p in pasture and got the same results. Notice the bizarre improvement in depth at sensitivity 60, discrimination 50! Not what I would expect, I got exactly the same anomaly.  I also got the same depths when I replaced the 5p with an Eddy hammered penny., about the same size I suppose.


Using a 14 month old T2 LTD, 11''coil, a small C/nickle coin @55, a lead .177 air-gun slug @43 in air test. Done by hand so a bit raggy.

IN GROUND TEST

...........................................Sens....43.............................55
Disc................................................177cal.......................Cupro/Nickle Coin.....(British 5 pence)
0 ....................................................5''.............................11.5"
1 ....................................................4...............................11
2 ....................................................3.75..........................10.5
3.....................................................3.50..........................10
4.....................................................3.25.......................... 9
5.....................................................2............................... 9
6.....................................................1.25.......................... 8.50
7.....................................................1............................... 8.50
8.....................................................1................................8.25................Signals start to get louder, cut off abruptly.
9.....................................................1................................8.25
10...................................................75..............................8.....................that's a .75 result, not 75
15...................................................0................................7
20...................................................0................................6.25
Disc....................................Sens.....................177cal..........................Cupro/Nickle Coin.....(British 5 pence)
20.......................................99........................3".................................10"
20.......................................90........................1...................................9.25
20.......................................80........................0...................................8.25
30.......................................60........................0...................................6.25
40....................................... ''.........................0...................................6
50.......................................''..........................0...................................10.50
Bp mode.
0.........................................40........................4.50"..............................12+"
1.........................................''..........................5.....................................12
2.........................................''..........................4.....................................11.75
3.........................................''..........................3.50................................11.75
4.........................................''..........................3.25................................11.50
5.........................................''..........................3.25................................11.0
6.........................................''..........................3.....................................10.75
7.........................................''..........................2.50................................10.50
8.........................................''..........................2.50................................10.50
9.........................................''..........................2.....................................10.25
10.......................................''..........................2.....................................10.0
15.......................................''..........................1......................................9.25
15......................................60.........................0......................................9.50
15......................................70.........................0......................................10.50
20......................................70.........................0......................................9.50
20......................................80.........................0......................................10.50
50......................................60.........................0......................................11
I don't understand what you mean when you say disc don't lose any depth. The figures are a bit rough but my test bed shows basically the same pattern,.... after a disc of 8 the signal tones get what appears a gain (louder) but it cuts off fast, as in,, it's there loud at full detection depth,,,, move the coil away a fraction no fade,,,, just gone.
50 disc seems to take it back to 2 disc, it chatters just the same.
Sorry about that, don't know why it's crushed all the columns up.


TerraDigger's results re-posted from "Teknetics T2 / A Gain Measurement Chart":

""Keep In Mind Indoor EMI Affects The Depth/Noise Results. Test Is Only To Show How Discrimination Adjustments on T2 Affect The Gain
(or something that acts like gain) Output""

AIR TEST

Model - Teknetics T2/Software version 6.5 (from 6.0 onwards version numbers make no difference in depth according to First Texas Products)
Coin Used - U.S. Quarter - Cupronickel
Coil - 5" DD
Sensitivity - 60
Tone Selection - 4

Discrimination Levels

0 - 9" depth reading (extremely noisy due to EMI & machines internal circuitry noise)
10 - 7" depth reading (approx 50% less noise than 0 disc setting)
21 - 6 1/2" depth reading (quiet)
30 - 6" depth reading (quiet)
40 - 6" depth reading (quiet)
49 - 5 1/2" depth reading (quiet)
50 - 9" depth reading (this is where another huge increase in Gain occurs, besides the zero setting. Same noise level as 0 disc setting)
60 - 9" depth reading (approx 50% less noise than 50 disc setting)
70 - 8 1/2" depth reading (quiet)
80 - 8" depth reading (quiet)

Observation - the Gain does not seem to follow a straight linear output as disc is increased. Notice that from 0-49 disc there is a 3 1/2" range in detection depth. From 50-80 disc there is a 1" range.

0r

If you remove the disc 0-9 results from above, there is a 1 1/2" depth range between disc 10-49 and a 1" depth range between disc 50-80.

The large gain increase at 50 and the 10-49 disc range has serious implications on how a user sets the discrimination.

Coin specifications used in both tests:

Value........5 pence British
Mass.........3.25 g
Diameter...18 mm
Thickness..1.7 mm
Comp........75%.Cu...25%.Ni

Value........5 cents U.S.
Mass.........5.0 g
Diameter...21.21 mm
Thickness..1.95 mm
Comp........75%.Cu...25%.Ni


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Dodger
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« Reply #1 on: April 08, 2011, 10:29:16 PM »

I have a T2 and found an American forum which said exactly what you have, that increasing disc past 50 will increase depth. I haven't tried it yet but  someone on one of the Scottish forums has found the same. Increased discrimination = increased depth. Goes against what we all believe that increasing disc will decrease depth. Any thoughts??
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Rob Two Spades
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« Reply #2 on: April 09, 2011, 10:21:20 PM »

Yes, it is odd but having discriminate on 50 gives you more depth than having it on 10, in fact its about the same as 7. I tested it and sure enough its true. Try yourself.
On good pasture I run it on Tones 1, Sens 80, Disc 50. Its quiet and very deep. On iron infested soil though I prefer Tones 2+, Sense 60, Disc 4 so I can hear everthing. If its really bad I'll use All Metals, Sens 45, in bP tones mode
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Grant
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« Reply #3 on: October 05, 2011, 12:57:53 PM »

I have a T2 and found an American forum which said exactly what you have, that increasing disc past 50 will increase depth. I haven't tried it yet but  someone on one of the Scottish forums has found the same. Increased discrimination = increased depth. Goes against what we all believe that increasing disc will decrease depth. Any thoughts??

Any more thoughts on this?

I've only just got a T2 so am trying to find all the info that I can..

I thought only decreasing Sensitivity decreased depth, not discrim with the etrac anyway
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