WTT Delta Pulse for Whites TM-808 without Cave mode

[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

[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

[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]

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]

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]

also, i have to add. there are 'earlier' TM-808 and 'last' TM-808. in last one Whites deleted CAVE mode (the switch) from the housing. so if you are seeking with CAVE mode you have to know the fact.
i put pics.

Yes...I know that, KT. The one I had included cave mode. Without Cave mode, a TM-808 doesn't help me much over the TF units I have, for what I'm doing. That iron Discrimination, in cave mode on the TM-808, really helps in what I'm doing. I bought a 6000 XL Pro (waiting on arrival) and am going to do some experimenting with that unit. It Also runs at 6.59khz, but has all the features the TM-808 lacks. I/m going to see if I can put separate Trans/Rec coils on it. Might be interesting. I'm going to need help from you engineers for that project. I thought I might use the coils (antennae) from an 808 , or TF unit.
Jim

[kt315]

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 TF900.

sorry, not. 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.

[Jim in Idaho]

I don't think so. AM mode is a VLF-GB mode that uses a synchronous demod. Cave mode and trace mode are both TR modes that use the peak detector so they likely both run at 73.5kHz. The trace box accessory is just a copy of the 73.5kHz TX oscillator so you can separate the TX coil from the main box, lay it on the ground, and use it to "passively" energize a buried pipe (passive coupling). You can also directly attach it to an exposed pipe (direct coupling).

The White's TM has a confusing history. I believe the TM600 was made by Karbowski (his company name was "3D Electronics") for White's. Then Karbowski licensed the design to Discovery who made the TM800 for White's. Then White's decided to do the manufacturing themself and created the TM808, which was identical to the TM800/TF900, including the TR Cave mode. Discovery complained about White's using their design, so White's redesigned the TM808 to use a CM6000 circuit and dropped the cave mode. 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 TF900.

yeah...I'm starting to get this. Running at 73.5khz in Trace, with the TF1200, give me a really "noisy" image with the data logger, regardless of the settings I have on the 1200. That higher frequency appears to see much more ground minerals, and it shows in the image. I tried turning the gain and threshold completely down, and still get a much noisier image than I get in all metal. Operating at 73.5khz might explain that. Thanks, Carl! Hope your field work is going well. I feel bad I couldn't get you the 5000. As an aside....I found out there are two boxes associated with the Trace attachment. One is the "transmit", and the other attaches to the receive coil on the TF900. Finding that out explained the pic I remembered seeing of a box attached to one of the antennae.
Jim

[Carl-NC]

So, the upshot of all this is the T/R (trace) mode, if a person is not using the special tracing boxes, is operating at the same frequency (12.5khz) as the all-metal mode.

I don't think so. AM mode is a VLF-GB mode that uses a synchronous demod. Cave mode and trace mode are both TR modes that use the peak detector so they likely both run at 73.5kHz. The trace box accessory is just a copy of the 73.5kHz TX oscillator so you can separate the TX coil from the main box, lay it on the ground, and use it to "passively" energize a buried pipe (passive coupling). You can also directly attach it to an exposed pipe (direct coupling).

The White's TM has a confusing history. I believe the TM600 was made by Karbowski (his company name was "3D Electronics") for White's. Then Karbowski licensed the design to Discovery who made the TM800 for White's. Then White's decided to do the manufacturing themself and created the TM808, which was identical to the TM800/TF900, including the TR Cave mode. Discovery complained about White's using their design, so White's redesigned the TM808 to use a CM6000 circuit and dropped the cave mode. 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 TF900.

[kt315]

also, i have to add. there are 'earlier' TM-808 and 'last' TM-808. in last one Whites deleted CAVE mode (the switch) from the housing. so if you are seeking with CAVE mode you have to know the fact.
i put pics.

[Jim in Idaho]

Thanks, KT! So, the upshot of all this is the T/R (trace) mode, if a person is not using the special tracing boxes, is operating at the same frequency (12.5khz) as the all-metal mode. The advantage the TM-808 W/Cave mode has is that when in the Cave or T/R mode it has iron discrimination. The Treasure Finder series do not have that in either mode. Thanks again for the help.
Jim

[kt315]

ok. i see your native is english so you will read patent easely. for a PIPE seeking, not for the gold mask.

[Jim in Idaho]

Hey KT....I have a question on the TF900/1200. Since Trace mode, with the attachment, works at 73.5khz, and the TR mode is also activated in Trace mode, does that mean the TR mode also operates at 73.5khz, or can TR operate at it's own, separate, frequency alongside the Trace mode? Iveca, or other engineers feel free to answer, also. Thanks
Jim.

[Jim in Idaho]

sorry but Trace mode is just with specific attachment. can you show it me?

I'm way out in the mountains prospecting. But you're incorrect. Trace mode performs very much like Cave mode in the TM-808. No attachment needed. It also ignores large iron in that mode, to some extent. It's all mentioned in the owners manual, KT.
Jim

[kt315]

sorry but Trace mode is just with specific attachment. can you show it me?