Latest TDI SL mod..

Jim in Idaho

Silver Member
Jul 21, 2012
3,313
4,684
Blackfoot, Idaho
Detector(s) used
White's GM2, GM3, DFX, Coinmaster, TDI-SL, GM24K, Falcon MD20, old Garrett Masterhunter BFO
'Way Too Cool' dual 18 Watt UV light
Primary Interest:
Prospecting
I've always had trouble getting the GB and Threshold exactly right on my TDI SL. After seeing Karelian's thread on the vernier knob, I decided to see what I could come up with. The problem with the control the guy suggested to him was that it had limited movement. Ideally, you want the vernier to turn as many turns as need to move the potentiometer through it's full range of travel. After hours of searching I found what I needed. A solid brass and stainless vernier with a 1:6 ratio. One full turn moves the GB pot about 1 1/2 numbers. I can now easily get the GB to that "just quiet" point, and it stays put. No more tree branches, or coat sleeves inadvertently moving the controls. I can easily set the Threshold to the very edge of my hearing, and as the batteries discharge and the Threshold creeps up, I can make a tiny adjustment and it's back on the money. As far as immediate and stark difference, this is the best mod I've done. It took me several hours to machine the bases, but the way I made it requires no physical mods to the machine. Remove the pot nuts, put the base on and replace the nut. I had to make shims for the pot shafts, as the verniers are made to fit a 1/4" shaft, and the shafts on the pots Whites used are .234". Had to make some very thin-walled round shims to glue inside the vernier sockets. I'm planning on selling these kits fort $150 for both controls, or $75 for a single. If anybody is interested, you can PM me here.

Now I'm really looking forward to our Nevada trip in June! My SL is about as good as an SL will ever be. It's going to be interesting.
P5310006.JPG P5310007.JPG P5310008.JPG
 

chiil

Greenie
Jul 31, 2010
16
1
Denver
Detector(s) used
DFX 300 w/ Sun Ray Probe, TDI SL SE
Thanks for the tip. Believe you have them listed on Ebay as well.
 

OBN

Gold Member
Dec 30, 2008
6,527
7,004
Maryland Waters
🏆 Honorable Mentions:
1
Detector(s) used
"Excalibur"..
"AQ" Impulse
Primary Interest:
Other
Funny I encountered something similar on the Minelab Excalibur, With the knob it was very hard to get that fine tuned adjustment of the threshold.
So I put a pin in the knob so now it can be moved with the touch.
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I also removed the other 4 knobs from contact with the saltwaters.... which was causing all of the noise when the Pod came in contacted or splashed. The one knob that is still there is insulted from the board by a plastic insert on the pots shaft.
 

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