Coiltek 6" mono Tdi coil. First impressions & small coil comparisons.

[karelian65]

I've got a Detech 8" mono for a while so I thought I'd give it a go, always suspected this size coil would be ideal, given my experience with the Sadie. I've done the usual air tests and it was better than the Sadie or equal. Had an opportunity to give it a very quick ground test near Creswick. All tests done on the Tdi Pro. Air test was full gain and ground balance OFF, pulse delay was 10, frequency centre. Sorry didn't record exact settings with ground test but ground was mineralized.
1 grain ingot 12cm, same as Sadie.
5 cents was 35cm, beat Sadie by 5cm.
3 pence was 35cm, beat Sadie by 5cm.
.5 gram gold coin was 30cm to equal the Sadie.
1/2 Sovereign was 38cm to beat Sadie by 3cm.
Penny was 37cm beating Sadie by 3cm.
Buckle came in at 60cm.
Us Quarter was 35cm.

Ground tests were a bit rough since time was short. Settings not recorded but depths on .5gram gold coin was 19cm, Sadie was 21cm . Half Sovereign came in at 30cm depth, beating Sadie by 3cm. So Sadie wins on the small gold but Detech 8 mono might be better as the size increases. That Detech looks to be very well made and solid, very quiet and well behaved. Mounted on Minelab lower rod, balances nicely and no weight problems, very nice quality coil.

Detech 8" mono seemed to nip at the heels of the Sadie on smaller gold, jury is still out since tests were rushed. It goes very deep on some targets and could be close to the ultimate all rounder. Early days and I'll report back later with more detailed results. I've been asked to put some Lithium batteries in the new Special Edition Tdi SL so it's running on 14.8 volts and compare it to the Tdi Pro, no problems, happy to do it but just need a bit of time to do it properly. Whites may have made some minor cosmetic changes to their Tdi Sl plus other changes after the SPP hiccup issues were resolved. Not sure but we can find out if 2018 machines outperform 2012 models..?

All the best,
Karelian.

 

[PhaseTech]

Detech 8" mono is a real sleeper. Kind of looks made for the TDI with the white, black and gold colour scheme.
Thanks for the report

 

[karelian65]

I've got the Tdi Sl as a loaner for family and friends. My brother and friend who accompany me feel that they are disadvantaged with the 'lighter' machine, I'm inclined to agree but so far have not put it to the test. It is light, easy to use etc and I'm not giving up the Pro. The 'new' Sl looks good and I like the new handle, I'm using it on the beach a lot and so far it has performed well. It will gets its first taste of the goldfields shortly. The Pro and Sl have a strong family resemblance with build quality, weight and balance excellent. Just a few more photographs and next post will be a proper collection of coil tests and detector comparisons.

I think it looks good in this colour.

No screen or touch pad.

Same but different..
All the best for now.
Karelian

 

[karelian65]

It has been quite a while since I've used these disposable lithium batteries, cost being the reason. Voltage comes in at 14.3 not 14.8 as I had hoped. Just a few images to confirm tests, results to follow.

I'll start with the dreaded air test shortly, ground testing will follow in good time.
Karelian.

 

[Ridge Runner]

I made a 9 Cell box and with those batteries it will give out about 16+ volts, It was me who wrote the thread over on DP about the TDI Battery box conversion.

 

[karelian65]

Yep lots of options to increase voltage, 4x 18650 is looking good right now. Air test with gain on max, conductivity on ALL, delay on 10, frequency in the middle, ground balance off.
Ground testing will tell the real story though later on. Again voltage was 14.3 just prior to test.

No EMI issues today, Detech seems immune when on Tdi SL.

1 grain was 8cm
5 cents 30 cm
3 pence 31 cm
0.5 gram gold coin 25 cm
1/2 Sovereign 34 cm
1 penny 32 cm
buckle 50 cm
us 1/4 was 30cm

Time to take the dremel tool out and butcher a battery box, 4 x 18650 should do the trick. They are hot fresh off the charger but settle to an honest 14.8+, no stories of machines blowing up yet so I'll give it a go. To date I use those Ukrainian 3 x 18650 packs instead of White's factory rechargeable packs.
Thanks again.
Karelian

 

[Ridge Runner]

be careful with those 18650's because even when they have sat for 24/48 hours they still hold 4.2v which is 16.8, the saffty limit on the TDI's is closer to 16v, Max.

J.

 

[karelian65]

Diy 4 x 18650 battery pack is on the list of things to do, but in the meantime... Bought some alternatives to the Energizer batteries, Wallaby disposable lithiums. Battery pack comes in at 14.72 Volts. So I'm happy at the voltage. Easy to spend $100 on fuel when I go prospecting, same for a night in a motel. That $100 buys 48 of these batteries. Cheaper than Energizer and a little hotter as well. Another air test to follow, this time with the supplied Miner John folded mono coil that came with the Tdi SL special edition..

That Voltage at 14.72 looks good enough for me, for the time being..

I got them off fleabay in Australia, can't argue with the price when compared to the Energizer's..

Fresh alkaline Duracells come in at 12.8 volts total.. ok another useless air test..

Tdi SL Special Edition Gain at MaX, Frequency in the middle, Pulsed at 10, Ground Balance OFF. Miner John Coil.

Wallaby pack at 14.72 Volts

1 grain 8 cm
5 cents 32 cm
3 pence 30 cm
0.5 gram gold coin 25 cm
1/2 Sovereign 34 cm
1 penny 34 cm
Buckle 50 cm
US 1/4 30 cm

Duracell pack at 12.8 volts

1 grain 7 cm
5 cents 31 cm
3 pence 28 cm
0.5 gram gold coin 24 cm
1/2 Sovereign 32 cm
1 penny 33 cm
Buckle 47 cm
US 1/4 28 cm

Should mention the Miner John coil didn't pick up any EMI, it runs smooth and quiet at all times, beach and goldfields. Balances well and is very light weight, well made no issues. Uses Whites lower stem and coil fittings etc. For such a decent size coil is is very light weight.

Again all the best,
Karelian

 

[karelian65]

After reviewing my results I'll include a quick note, early air tests were done with gain at 5, more recent tests were done with gain at MAX. My home WIFI was replaced with well shielded cables, so far less EMI, making MAX on the Tdi Pro nice and smooth. In the air tests that adds about ten centimetres, roughly; to the buckle for example. Ground testing results are not effected since they were done out in the field.

The SL seems more resistant to EMI than the PRO, probably due to the filtering to get that smooth threshold. Never been able to find ground on the goldfields that allow MAX gain with the PRO. Max Gain is only on the beach and with the ground balance off as well for great results. The SL will sometimes allow MAX gain on the goldfields, particularly stable and smooth in the LOW setting, whilst passing on some ground noise in ALL. I always bring a test nugget to 'tune' the detector for the location. Play with the settings to get the best performance for that location. Some coils will pass on some, more or less, ground noises when pushed for depth and sensitivity, these noises are easily distinguished from targets most of the time but not always. The coils do behave differently from one another in regards to smoothness and stability in high mineral soils. Perhaps something I should have explored in more detail. Sometimes we need to pass that coil over some ground noise again, maybe from a different angle and even play with the conductivity switch or other settings since some hot rocks etc can and do sometimes sound like a possible target.

I only need to grab a VLF detector in hot rock infested ground to remember how much better PI machines operate in such areas. When working near Rifle Range Rd in the Whipstick I did swap my Tdi Pro for my MXT, but only after about 100 full metal jacket 303 British projectiles were dug by me. Lots of bullets, boot tacks, buttons and other bits and pieces but no gold. I cannot set the Tdi machines to ignore bullets or any lead targets, too similar to gold. Maybe I'll find another spot well away from old rifle ranges..?
So max gain is not always possible or desirable, for me the goal is to set the machine up to be smooth and stable which can only be done at times by turning down the gain.

Again all the best.
Karelian

 

[karelian65]

Just a quick note that XLOOX has posted a nice simple battery solution for Tdi SL owners. Check out his post, it came at a good time for me. Again full credit to him. Nearly finished my copy and then it is game on. Nice solution with locally sourced components and materials, low cost and simple. No drama putting it all together. Just loving it.

All the best,
Karelian

 

[karelian65]

Thanks to XLOOX I now have a 16volt plus battery holder, that is 4 x 18650 cells for 16.48 volts, perfect for the Tdi SL. A quick test to see if it was all worth it, just to see what gains were on offer. Using the SL Limited Ed, with the Super Pulse 220 coil there was some improvement. Started with the Ukrainian 3 x 18650 pack which came in at 12.38 volts, compared to the modified pack with 4 x 18650 cells at 16.48 volts. Then compared those results with ones from a Tdi Pro using the same coil.

Tdi Sl with gain at max, GB off, Pulse Delay at 10, in all frequency middle. Using Super Pulse 220 coil,

12.38 volts gave 6cm on a 1 grain ingot, 24cm on 0.5 gram gold coin, 32cm on gold Half Sovereign and 27cm on a US Quarter.
16.48 volst gave 8cm on a 1 grain ingot, 26cm on 0.5 gram gold coin, 35cm on gold Half Sovereign and 30cm on a US Quarter.
Tdi Pro gave 8cm on a 1 grain ingot, 27cm on 0.5 gram gold coin, 36cm on gold Half Sovereign and 33cm on a US Quarter.

The Tdi SL was on MAX gain, the Tdi Pro gain was set a 5.

All the best,
Karelian

 

[Rustynails]

Excellent review as usual Karelian.
So it seems that the extra voltage gives approximately 10% depth improvement, but that may not be be the main advantage. When the 4 cell pack fades to 3.1v per cell it will equal the 3 cell pack with fully charged batteries. When the 3 cell pack fades to 3.1v per cell the SL will be running at 9.3 volts. Ive read reports claiming that the SL suffers noticeably by the time disposables hit the wall at 8.5 volts.
Food for thought.

 

[karelian65]

Just arrived in the mail, Nuggeteer 18 x 6 mono. Looking forward to giving it a run and seeing how it performs on the Tdi machines. Hoping to use it as a beach coil, should cover a lot of ground. Full review to follow later.. Karelian

 

[karelian65]

When the weather clears I'll get out and do some testing.

 

[karelian65]

The useless air test to begin with. Gain max, Pulse at 10, Ground balance OFF, Conductivity in ALL. No EMI, smooth and quiet operation. 18 x 6 mono Nuggeteer coil.
Australian $1 coin was 37cm
Australian 5c coin was 30cm
Australian 3 pence 30cm
1 grain ingot 5cm
US 3 cents Buffalo 34cm
0.5 gram gold coin 22cm
half gold sovereign 34cm
US quarter 28cm
Australian Penny 36cm
Whites Buckle 51cm

Key is coverage, so performance is very good for this type of coil. Very quiet, NO EMI issues... Karelian

 

[karelian65]

When setting the machine up to reject small iron, expect roughly a 10% drop in depth. Using setting of delay at 13 or 14, ground balance between 5 and 7, gull gain, frequency in the middle and delay at LOW, small iron is tuned out. Use a bit of small iron to fine tune the machine for your location and for your particular machine.. Gold still hits hard but with that quoted 10% loss in performance. The 1 grain ingot is not detected by the Nuggeteer 18 x 6 mono when tuning out iron. The half gram gold coins looses 2 cm, from 22 cm to 20 cm. The Half Sovereign went from 34 cm to 31 cm. All strong clear signals and no small nails, hairpins, or fish hooks. Lost also were $1 and $2 dollar coins, pennies etc.. At least I know the Nuggeteer will perform well using all settings on the Tdi machines, no issues and surprising for a coil this size, NO EMI so far.. Karelian

 

[karelian65]

The Nuggeteer 18 x 6 matched to the Tdi Pro seems to be the ideal beach combo. Managed max gain on two out of three locations. Large coins like the Australian 50c can come in at 35cm in the sand. A lot of ground covered fast, no issues with wet sand or salt water, works on all settings. I'll give it a good run over this summer on the beaches and later in the year I'll take it out into the goldfields. So far I'm impressed by the coil. Karelian

 

[ronniecruisin]

Hi. Karelian. Who makes them and how much do they cost. Can't find any info other than yours on the net... Regards... Ronnie.

 

[mbasko]

PM Coils (PulseMate) made them.
See them come up on eBay etc. sometimes.

 

[karelian65]

Made by Pulse Mate, no longer in the game, these coils pop up on gumtree and fleabay. Paid $60 for the 12x4 Anti Interference coil and $175 delivered for the 18 x 6 mono. The bigger coil is perfect for the beach, I've got little use for the other smaller one. They look odd, but balance well and cover lots of ground fast. The larger 18 x 6 is classified as a 'patch finder' coil. Frustrating that they are no longer made. But my advice to anyone is, if they spot one in the classifieds, they are well made and good performers.. highly recommended. All the best, Karelian.