TDI SL Ground Balance Tests..

[Jim in Idaho]

I finally had time to do some testing on the SL, regarding the Ground balance. Here's the result:

TDI SL GB TEST

 

350 Super Pulse coil. battery voltage at start of test = 16.0v

Freq. max., Switch in "ALL", Gain MAX, Pulse delay MIN.

1979 US nickel Sweeping side-to-side. The test setup was having the detector vertical, with the coil on top of a 5 gallon bucket to minimize the ground effects. I taped a yardstick to the shaft. I did NOT use headphones, but did repeatedly sweep the nickel to try and get honest results.

 

GB off

13"

GB on:

2     14 1/2"

3     15 1/2"

4     15 1/2"

5     15 1/2"

6      14 1/2"

7  to 11    15 1/2"

 

Freq. set to minimum

GB off same

GB on:

2     14 3/4"

3     14 1/2

4     14 1/2"

5     14 1/2"

6 thru 11      15"   

 

Switch to 12"DF coil

GB off    17"

GB on:

2-5       17"

6-11     16"

 

12DF with 1 grain gold bar

GB off     3 1/4"

GB on:

2-11  3 3/4"

 

Both coils with 6 gram men's gold ring:

 Both coils detected this very close to the same as they did with the nickel. But, turning the GB on and off had very little effect on the depth. It's apparent to me that on some items, my detector is definitely better with the GB on, but set to 2, or minimum. But on larger gold, the GB has little effect. But what effect there is favors having the GB on, but set to minimum. There was only one instance where having the GB off was an improvement.

 

 I also tested my NF Sadie 8 x 6, and was surprised to see it was LESS sensitive to the 1 grain gold bar, than the 12"DF. The Sadie struggled to make 3". For me the best coil is the 12"DF, where it can be used.  Where it's too cumbersome, I'll go to the Sadie.

The Sadie was better than the 7 1/2"DF, and the MJ 5 x 9. I sorta wish I hadn't sold the 7 1/2"DF...I'd like to test it more.      

 

I also tested a 1" thick x 4" diameter hunk of aluminum, with a 1 1/4" hole through the center. Neither coil could detect it near as well as they did the nickel.

Jim

[Mark Gillespie]

Thanks for taking the time to test and post your results.

I did notice your starting voltage was 16, this obviously tends to prove, more voltage, more depth capability. 

Your nickel test basically states that the nickel detection range does not regrade when GB is switched on, until GB is above 6, using the 12" dual field coil.  Very similar to my results with the US nickel.  You gain quite a bit over my unit using the same settings, very impressive. 
 

16 hours ago, Jim in Idaho said:

Switch to 12"DF coil

GB off    17"

GB on:

2-5       17"

6-11     16"

It would be very interesting to see the same test settings using a US dime and quarter.

I think you should notice a difference using these high conductors. 

Can you share how you came about the 16v battery pack?

 

[Jim in Idaho]

I did a quick test, with a quarter, on the 12"DF and it was about 11 1/2", Mark. The battery pack was purchased 3 years ago from a guy that goes by "Reidman" on Ebay. Last time I checked, he was no longer offering them, however. Now that I have one, I could build another pretty easily. I use a charger that the output voltage can be set to any desired voltage, so I can limit the final charge voltage to 16v. Standard chargers can't be adjusted, and don't stop until reaching 16.8v. The SL handles that OK, but you get more charge-discharge cycles from a pack by limiting the charge to 80%, or in the case of a 4-cell pack, 16.0v. Doing that will almost double the life of the pack.

 I think my SL is especially "hot". Just got lucky. It detects that 1 grain gold bar farther than my GM24K, or GMT.

 I think the reason the 12"DF is more sensitive than even the Sadie coil is the increased voltage. I'd bet, if I dropped the voltage to 12v, the 12"DF would not match the Sadie 8 x 6. I doubt the Sadie would decrease....the small coils don't benefit much from the added voltage. The SL is a good machine with the added voltage. Whites should upgrade the standard battery, IMHO. Or maybe re-design some components, and go all the way up to 21v.

 I was not impressed with the SP 350. I'd like to find a good 7 x12 mono for mine. LOL....that didn't cost an arm and leg.

Jim