TDI SL 2014 MODIFICATIONS

[Mark-VA]

Any know modifications to increase depth of the White's TDI SL manufacturing date 2014?
I've always heard that running this machine GB off gave a huge depth increase, but not this one.

White's TDI SL, manufactured 2014, pulse delay 10
Air Test	Freshly Charged Battery Pack
			GB OFF		GB OFF		GB ON MINIMUM		GB ON MAXIMUM
			GAIN MAX		GAIN 8		GAIN MAX		GAIN 8
7 1/2" Dual Field Coil			7 1/2"		7 1/2"		7 1/2"		7 1/2"
Super Pulse 350			11 1/2"		11 1/2"		11 1/2"		11 1/2"
12" Dual Field Coil			13"		13"		13"		13"
To be honest I'm kind of disappointed
Very smooth threshold In ground performance may be different

[kt315]

MG

can you give me pics in HR? must accumulate some info in archive. i think you must encrease POWER PULSE WIDTH
and change preamp on two stage. also make the fastest coil.
but if its done on two PICs then POWER PULSE WIDTH formed by the soft.

[Carl-NC]

What target are you using?
Are you sure the GB is engaged? Does it produce high/low tones?
Yes, GB mode loses an inch or 2.

Finally, I hope you got the 7-1/2" and 350 numbers backwards.

[Mark-VA]

Using a nickel
I tried it both ways, GB on and off, no difference.
I will double check the numbers though.

[Mark-VA]

When I got home I compared my notebook data to the data in my spreadsheet and it was wrong. The 7 1/2 came from a different line and it was to be the air test results of a ground balance setting of 7 1/2.
I did the test again and can't see any improvement when GB is off.
Yes I do get tone ID with GB on
For some reason, pasting data from a spreadsheet to here changes numbers around the 11 1/2" on the middle coil should be on the same line.

White's TDI SL, manufactured 2014, pulse delay 10
Air Test	Freshly Charged Battery Pack
			GB OFF		GB OFF		GB ON MINIMUM		GB ON MAXIMUM
			GAIN MAX		GAIN 8		GAIN MAX		GAIN 8
7 1/2" Dual Field Coil			11"		11"		11"		11"
Super Pulse 350			11 1/2"		11 1/2"		11 1/2"		11 1/2"
12" Dual Field Coil			13"		13"		13"		13"
To be honest I'm kind of disappointed
Very smooth threshold
In ground performance may be different

[green]

Surprised detection distance doesn't change with GB on or off with the nickel. Some measurements I made with my detector awhile back. mV measurements are integrator out. My circuit not a TDI but would think any PI would act similar. GB sample is subtracted from target sample, if the same(no signal GB). GB sample has more gain which should increase the noise when GB is on. The nuggets are short TC targets, mV signal almost the same GB on or off. Lost some detection distance because of noise increase? The nickel is a low conductor target, GB on or off. Starts to fall in GB hole with GB on. Looses detection depth because of noise and GB sample subtracts from target sample? The quarter is a high conductor target, GB sample greater than target sample. Increasing GB would increase signal and detection distance if noise didn't increase the same as signal. Probably not a lot if any. Maybe the TDI is different and I'm missing something?

[Orbit]

Surprised detection distance doesn't change with GB on or off with the nickel. Some measurements I made with my detector awhile back. mV measurements are integrator out. My circuit not a TDI but would think any PI would act similar. GB sample is subtracted from target sample, if the same(no signal GB). GB sample has more gain which should increase the noise when GB is on. The nuggets are short TC targets, mV signal almost the same GB on or off. Lost some detection distance because of noise increase? The nickel is a low conductor target, GB on or off. Starts to fall in GB hole with GB on. Looses detection depth because of noise and GB sample subtracts from target sample? The quarter is a high conductor target, GB sample greater than target sample. Increasing GB would increase signal and detection distance if noise didn't increase the same as signal. Probably not a lot if any. Maybe the TDI is different and I'm missing something?

The same is TDI ..

[bklein]

Are the DF coils unique to the TDI or same as what the DF uses?

[eclipse]

Schematic-wize there isn't that much you can do to modify the circuit board.
There's a low-level signal filter before the Gain stage that can be changed but this will introduce more noise.
If you're really feeling like modification is your thing locate R78 on the board (22K) and change it with 10K or 15K to reduce the noise reduction effect and get more gain.
No warranty on this modification, use at own risk.

[Carl-NC]

I did the test again and can't see any improvement when GB is off.
Yes I do get tone ID with GB on

Sorry, no idea what might be going on.

[green]

Sorry, no idea what might be going on.

What should the detection distance be for a nickel with the TDI?

[Carl-NC]

13+" all metal, 1-2" less in GB.

[Mark-VA]

Spent three evenings doing the same test each night to make sure of what I was seeing.
Yes, there is a difference on high conductor air test between GB on (minimum)USGA1007.pdf and GB off.
Yes, -2"
But no difference in a US nickel