Razorback coil, finally got it.

Yeah not worried about having it modded, just wasn't sure if that upgrade/mod was something they started doing from factory, but by the sounds of it it may have been part of the changes.
When I started using the SPP, I could run full gain with Whites 12" mono & Nimh pack, then I added con switch & it was still good. After that I changed to alkaline batteries to test it out, total voltage went from 9.6v up to 12v, with Duracells I get around 13.3v to start with. After changing batteries I started to find I was getting more interference of some sort, probably still to do with my tuning but it wasn't as noticeable with the lower voltage of the rechargeable's, with more voltage I have to be more accurate with tuning. Then I changed to the RB coil which is alot more sensitive & from what I understand, will pick up interference a bit more. So now with the RB coil & 1.5v alkaline batteries I am probably picking up much more interference from HV powerlines, phone towers & general emi from towns & probably weather as well. With all that happening, I needed to improve my tuning skills & needed to learn more about what changes to make, like being more careful with the frequency & lowering gain a little more than I had been. Getting the ground balance hasn't been to bad, specially when getting the frequency & gain set up better, it was like Karl mentioned above, "use full gain only in ideal conditions. It is most common mistake, full gain in hope to get best depth".
With the help from other forum members I have been able to get my tuning done much better & the SPP is running much smoother, now I think I just need to find the right places to detect, get out earlier in the mornings, rake some ground & cover an area properly.
Will still test a few things like depth on lead targets & with the test nugget we have & see how gain makes a difference as that should help me get a better idea of how things work.

Take it easy.
Paul.

any luck with the new coil yet mate?

No had no luck as yet but haven't actually been out to much with it, did find some deep lead & other stuff but no gold, just haven't really got out to the good area's that haven't been flogged as much. But lately we have been getting into the panning, also go a small high banker although still need a pump & hoses etc, so the detector has taken a rest for a bit, actually thinking we might even sell it if we can, just enjoying the panning & have found a couple grams already.

been checking out coils of late.

I see Miner John does a 5 x 9 DD, says it really reduces the ground balance on the TDI, even able to turn it off in some locations, giving greater depth.
I also note its not available in Australia, although it was tested here with good results, anyone have one?

I was present for some of the testing of a few of the double d and other minerjohn prototypes in early 2015 on a sl and a tdi pro in tarnagulla. Sensitivity seemed ok for a dd but was hard to get good ground balance and that made them a little noisy.
They were prototype coils so the final product may be better?

Daryl

Thanks daryl, what about the 5 x 9, mono, know much about that one.
I bought my TDI 2nd hand, and it came with a Razorback longreach, which is a really good coil, but I dont know how old it is, and it sometimes gets some horrific "warbaling sounds", which after some fiddling goes away, but its always in the back of my mind if its working as well as it should.
So looking at at getting a new coil.

Yes the 5x9 folded mono is dynamite on the small stuff. The 7x11 folded mono was my favorite on the spp as it was splitting hairs for sensitivity v the 5x9 ( picked up a .03 test nugget on the surface! ).
Just remember that the folded mono coils have a very sensitive area on the front 3rd of the coil for small shallow target's and behave similar to a normal mono on anything at depth.

Daryl

7x11 in action

https://youtu.be/e6qAHECjF5E

5x9 in action
https://youtu.be/0kLvzVNS-EY

Every time I watch an SPP video I can't help but notice the super stable threshold. It's like a GPX with the stabilizer turned all the way down.
But I think that's it's downfall. Too much filtering of the audio will desensitize the machine by a lot more than people think.

A couple of audio controls added where you can control the filtering/stability of the audio, and the peakyness (not a real word I know) of the response like the Signal control on the GPX's and I think you could squeeze a lot more performance out of it.

I'm not sure how the filtering effects performance etc, but I've found lead .22 bullets around 12 inches deep, maybe even a little more using good 1.5v Duracel batteries & the 7.5x12 RB Longreach folded mono, using the standard 12" Whites mono I found the same size bullets around 10+ inches. Not sure how if that means anything when trying to find gold but I thought it was decent depth.
The .22 bullets weight just over 1.5 grams I think it was when I had one weighed. Thats not running with gain at full either, it was maybe half to 3/4 of the way up.