WTT Delta Pulse for Whites TM-808 without Cave mode

[Carl-NC]

So there are 2 different TM808 models, with and without cave mode. If you get the one with cave mode, you are getting a copy of the TM-808 that has CM6000 circuit's Disc mode.
also, TM-800 is TF900, circuit is same.

No, the TM808 without cave mode is the one with the CM6000 circuit. The CM6000 did not have the peak detector circuit that is used for cave mode, so they dropped the cave mode when they re-designed to use the CM6000 circuit.
Yes, the TM800 is the same as the TF900, because Discovery made both of those.

[Jim in Idaho]

There's another difference between the TM-808 W/Cave, and the TF units.. The TM-808 I had, with Cave, did not respond to large iron targets near the surface when in Cave mode....my TF1200 does when in Cave/Trace mode. That TM-808 has some form of iron discrimination in Cave mode. I tested that repeatedly, and it wasn't a fluke. It would not respond to my iron-handled, iron-headed geology pick lying on the ground, but had no problem with a couple of pop cans nearby. I really wish the TF units had that! I'm wondering, too, if I can put the coils from an 808 on a CM6000. I can do the machining, etc, but not sure about the electronics of doing that. I've got a CM6000 on the way.
Jim

[Carl-NC]

I don't know why the 808 would ignore iron, certainly the peak detector used in the Discovery circuit cannot distinguish ferrous/non-ferrous. I don't have an 808 with cave mode to try. Probably it's not too difficult to adapt the 808 coils to the CM6000.

[Jim in Idaho]

Thanks, Carl. I'm trying to buy back the 808 with cave I sold in May. If I get my hands on it, I may send the box to you this winter, so you can look at the circuitry. Maybe it was modded by a previous owner? That's good news on the coils working on the CM6000.
Jim

[Jim in Idaho]

There's one sentence in the Owner's Manual, on using Cave Mode that says "the detector may lose it's Threshold when passing over large changes in the ground density or mineralization". Maybe it was seeing the iron pick as that, and went silent?
Jim