TDI SL mod...

[Idaho Jim 235]

I posted this to other forums, and thought it might be of help, so am posting it here, too.

Bit the bullet and did the sweep speed mod this morning. Made a huge difference in the acceptable SS. I ran the 1 grain gold bar past the 8 x 6 Sadie coil before doing the mod, and there was a relatively slow, specific sweep speed that gave the best signal. Too fast, and the signal completely disappeared. After the mod, the SS made almost no difference. Fast, slow, the signal was steady. No change in indicated depth in the air test. Threshold was still smooth. I'll post a video of the before/after tests later on. I changed the filter caps (C20, 21) from .47ufd, to ,22ufd. A friend in Florida, who is a civilian tech working for the Navy, was kind enough to send me a few matched pairs of the caps. Without his encouragement, and help, I probably never would have tackled this. Now I'm really glad I did. One tool I'm glad I had was my fly-tying magnifying light. My eyes don't focus like they did when I was young, and that magnification allowed me to see the soldered spots, to be sure I had done a thorough job.  You can see the difference in sweep speeds, before and after the mod, here:

Sweep speed comparison

[Idaho Jim 235]

I did both of Reg Sniff's suggested mods to my 2013 model TDI SL. I also use a 16v battery pack. I was testing it yesterday on pieces of nickel. I buried a 1 gram piece at 6", and a 1.84 gram piece at 10". The TDI saw both with the 7.5"DF coil, and the 8 x6 NF Sadie coil. The 12"DF coil could only see the 1 grammer....same for the Super Pulse 14" 350. The signal on the 1.84 grammer was faint, but repeatable. I'd definitely have dug it in the field.
Jim

[garikfox 77]

That's cool !

I'm assuming the stock battery isn't 16V?

[Idaho Jim 235]

Stock on the SL model, and the Special Edition model of the SL is 12v.

Jim