I've been experiencing lower yields due to sites being detected, by me for sure and there are also signs by others previously. SchoolofHardNox's success on a beach using the Minelab GPX 5000 reminded me to re-read Steve's treatise on using the (in his case original big box Pulsescan) TDI for coin detecting.
I just a few days ago stumbled upon a promising site where extra depth could be key. It's a schoolyard going back at least to 1955. Unfortunately as is the case in many of my public sites, it has a history of backfilling. From aerial photos I see than in the 50's it was grass/sod covered but in the early 60's they put down gravel. The person who told me about the site (a person who walked up to talk when he saw me hunting a nearby park) said he was a student there 45-50 years ago and at that time it was (again) grass/sod. I did a one hour survey hunt with the Minelab Equinox (11" coil) and encountered a couple inch thick gravel layer about 5" down. I did find one Wheatie below the gravel, but 7" is getting deep for my detector + soil mineralization combination so if coins remain from the 50's (pre- gravel layering) then I expect I will do better with extra depth (and that may even be required).
One thing I've found in my detecting of these older sites -- there are always nails present. So even if my TDI/SPP can deliver in the coin category it's going to be signalling on a lot of nails. One of the tricks Steve used was to set the conductivity switch to high conductors (low tones) but the TDI/SPP doesn't have that feature -- I will be hearing both high and low tones. This is a dual disadvantage -- extra tones to have to mentally tune out but also extra threshold noise since both parts of the signal spectrum will be contributing to that as compared to only half when the conductivity-low switch selection is made (on all TDI's except the SPP version).
Here are some specific concerns:
1) Am I fooling myself thinking I can get extra depth with the TDI/SPP, particularly when it comes at the expense of a noisier threshold?
2) Which coil(s) should I be using (choices I'm considering are 6"x8" Nugget Finder Sadie mono, 7"x14" NF mono, and 12" round White's 'Aussie' mono)?
3) Should I flag the promising targets but double check with the Eqx 800 (and if so, should I use the 11" or 12"x15" coil on the 800)? (Note, even if I choose this route I will likely at first dig, regardless of what the 800 says, just to get an idea of what is giving the signal and how deep the targets are.)
Any other advice (from anyone) is appreciated.
I have an easy and maybe stupid question to present now...
Observing my TDI Bh, with both of the coils I own (the original 12" and the aftermarket Detech 8"), I can clearly see way too long wire around the shaft and I'm forced to make several loops up to the control box near the handle.
Supposing to measure the right lenght for the maximum extended shaft, and to cut away the hipmount mile long cable.....Am I doing a disaster or not?
I actually can't remember the technical cable's specs in the amazing pdf Steve posted time ago, but if I'm correct it talked about to reduce some current resistance with a slight performance improvement too...Have I seen a mirage or what?...
I'm not kidding 😜...
It's just me, looking for something to play with, suffering for a missed AQ.
I opened up my TDIBH the other day for some fiddling around and checking out a few things. I powered up the detector with all of the guts and board opened up and had it hooked up to the 14.8v (4 x 18650 cells) battery pack. I had it going for just a few minutes when I gripped the circuit board as part of my “fiddling” around......well I dropped the board and swore a bit in response the burn I was expecting on my fingers. Well it turns out that on the opposite side of the board behind where the big capacitors sit is some sort of heat sink and I can tell you the heat from this spot was something else. The detector has and runs just perfect but the hotspot really surprised me.
I decided to hook up the 12v battery pack and let it run for a decent amount of time and it never got past a mild warm on the back of the board. That extra couple of volts is generating some serious extra heat.....bit like on the heat sink area of the CPU chip in your computer.
I honestly don’t know if the detector can handle this extra heat long term but I’m not taking any chances. I’ve moved back to the 3 x 18650 battery pack which I knocked up when I first got the detector. There is a slight loss in depth but surprisingly not too much. I feel the performance of the 11.1v Lithium setup is maybe 1 to 2 inches behind the 14.8v “hot pack”.
You can see in the photos the big caps on the detector and where the heat comes from. The other photo is my 11.1v pack which packs some punch and lasts much longer then the stock NiMH pack.
Is the main difference between the TDI Pro and SL is gb course and fine adjustments? Is there any power difference between the models? An old friend might be selling his TDI and I believe it is one of the older Pro's and I might snag it.
Also what 3rd party coils work with them?