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New Equinox Coils From Coiltek


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I really don’t see much advantage to any of these new coils over the stock coils.  I can understand gold hunters embracing the 5x10 for more coverage while keeping a high sensitivity to small gold.  I really don’t see any advantage of the 9x14 over the 11” stock.  Most likely less depth with 3” more coverage.  Maybe it’s more aqua dynamic (is that even a term? Lol) than the stock 11” for water hunters.  I can see a use for the round 15” though.  More depth and more coverage than the 11” and more depth than the 12x15 stock coil.  I can see it’s advantage in wide open plowed fields. Am I being a debbie downer on these new coils?  Lol

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1 hour ago, NCtoad said:

Am I being a debbie downer on these new coils?  Lol

Not necessarily a downer point of view, these coils are going to make some folks happy, others not so much. 

The only problem I have with the 15" round is adding more weight to an already nose heavy machine.  It's not like you are going to gain 4 or 5 inches over the stock coil or the 12x15.  So the question is the whether the weight is worth it for maybe 1 or 2 inches max depth under ideal soil conditions.  Hot soil, the additional coil footprint is actually counterproductive.

5x10 is great not just for gold seekers but also for relic hunters in cellar holes, thick scrub  and in thick iron patches where swing angle is limited and the additional coverage over the 6" round helps and when the 6" round depth performance (which is decent) is good enough.  I can't stand the miniscule swing coverage of that 6" round, but its small target sensitivity and depth are great as well as the ability to swing it in tight spaces.  The 5x10 fits the bill and fills the gap.

I am not sold on the 9 x14 yet.  Seems like it is just a tad too long and am not sure the additional weight is worth it, but it could be a good hot field coil with the right footprint and coverage vs. the stock.  We'll see...

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Coil Weight and Footprint Specs for comparison:

ML 6" round:  300 g, 6" wide, ~28 sq in., CWR .02/AWR .093

Coiltek 5x10" elliptical:  426 g, 5" wide, ~39 sq in., CWR .023/AWR .092

ML 11" round:  510 g, 11" wide, ~95 sq in., CWR .022/AWR .186

Coiltek 9x14"elliptical:  880 g (!), 9" wide, ~99 sq in., CWR .016/AWR .112

ML 12x15" elliptical:  660 g, 12" wide, ~141 sq in., CWR .023/AWR .214

Coiltek 15" round:  836 g (note this weighs LESS than the 9x14), 15" wide, ~176 sq in., CWR .018/AWR .211

CWR = Coverage/Weight ratio in in/g = subjective measure of swing coverage per unit weight.

AWR = Area/Weight ratio in sq. in/g = subjective measure of performance per unit weight.  Really only good for comparing coils of similar dimensions.  As you can see the small, and large coils are fairly similar in their AWRs.  Notice, however, the 9x14 weight and AWR which is really low compared to the 11" round and its total weight is GREATER than the 15" round coil.  The reason for the discrepancy is apparently Coiltek added weight to the 9x14 to facilitate submerged water hunting (discussed in the Coiltek link below).  Certainly takes it out of the running as a substitute for either the 11" or 15x12" ML coils on land.  If you want raw depth and good coverage on land, go with the 15" instead.  If you just need coverage and slightly better or equivalent depth to the stock, go with the 15x12 which weighs more than 220 grams less than the 9x14 despite having 1.4 times the footprint.

Source Data: https://www.minelab.com/usa/accessories?type=350307 and https://coiltek.com.au/coils/nox/

coiltek-searcj-coils-for-minelab-equinox.jpg

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   My situation is, all i have is the stock 11" coil! Of which #3 (broken coil Tab) will soon be on it's way back to me brand new! I held off buying other sizes due to the coil tab issues!

   So, should i just sell the new Nox coil when it arrives? And just buy two or three of the Coiltec's?

  That's sort of the way I'm leaning at this point! And there is the one year warranty difference between brands to consider!

  Any thoughts? 👍👍

   

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10 hours ago, TexasMike said:

When you need to maneuver tight spots and detect in high trash areas, this little coil offers superior sensitivity and pinpointing ability. Compatible with the Minelab Equinox 600 & 800 detectors.

Size (mm): 240x135mm
Weight: 426g 
Waterproof: Yes - fully submersible – waterproof to 3m / 10-feet
Warranty: 2 Years from date of purchase
Configuration: Double-D (DD) coil

That seems in the ballpark of other similarly sized coils although maybe on the higher end of the distribution since it was weighed without cover, I assume.  Here are some comparisons (my measurments except as noted; all are DD's except as noted).  Note that some dimensions are measurements I've made while others are what is advertised by manufacturer, so this might account for some of the variation:

Mars Sniper 6"x10" open (for Fisher F75), no coil cover (they don't make one for it) -- 392 g

Fisher 5"x10" closed for Fisher Gold Bug, w/coil cover -- 460 g

Nel Sharpshooter 5.5"x9.5" open (for Fisher Gold Bug) w/coil cover (?) measured by Phrunt -- 424 g

Minelab 5.5" x 9.5" 18.75 kHz closed for X-Terra 705 (no coil cover; not waterproof) -- 386 g

Tesoro 5"x10" 4-pin open (stock on Lobo Supertrack) w/coil cover (waterproof??) -- 434 g

Miner John 5"x9" folded mono closed (for White's TDI) w/coil cover (waterproof??) -- 384 g

 

 

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3 hours ago, Chase Goldman said:

The relative depth of an elliptical coil such as the 15x12, is tied more closely to the width dimension (12")....

I know you've said this before but I'm wondering what this is based upon.  Is it theoretical or found with measurements/experience or ??.  My limited measurements have indicated depth for USA pennies and nickels goes as the geometric mean (square root of the product of the two axes) so dependent upon both.  Other factors, espeically ground mineralization, can be large contributors as you and most(?) readers know.  I've not done comparisons in air.

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26 minutes ago, GB_Amateur said:

I know you've said this before but I'm wondering what this is based upon.  Is it theoretical or found with measurements/experience or ??.  My limited measurements have indicated depth for USA pennies and nickels goes as the geometric mean (square root of the product of the two axes) so dependent upon both.  Other factors, espeically ground mineralization, can be large contributors as you and most(?) readers know.  I've not done comparisons in air.

This is interesting!  If true, the stock coil has almost the same theoretical depth as the 9x14 coiltec.  

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36 minutes ago, GB_Amateur said:

I know you've said this before but I'm wondering what this is based upon.  Is it theoretical or found with measurements/experience or ??.  My limited measurements have indicated depth for USA pennies and nickels goes as the geometric mean (square root of the product of the two axes) so dependent upon both.  Other factors, espeically ground mineralization, can be large contributors as you and most(?) readers know.  I've not done comparisons in air.

It's a quick and dirty way to conservatively (i.e., underestimate) depth performance for a DD - it sort of breaks down quickly if you are not comparing similar sized coils. The field strength is probably more accurately tied to footprint but the length dimension of an elliptical coil contributes most to field shape vs. strength (i.e., coverage) because the sweet spot of the coil field is down the center of a coil for DDs.  So if you want to compare an elliptical to a round coil the more "accurate" comparative metric would be areal footprint (but that could "overestimate" the comparative performance of an elliptical to a round for the reason stated above) - for a round coil that is pi * radius squared, for an elliptical coil that is 0.25 *(length * width) * pi.  See my post above that compares the coil specs and gives a subjective metric of performance vs. coil weight.  The Coiltek 9x14 weight seems high.  Also, keep in mind, that the field strength does not necessarily scale linearly with increased footprint.  It sort of tails off and also the medium (air vs. soil vs. soil type and mineralization) has a bigger effect the larger the coil gets.  That's why the coils that are x inches larger/wider than the 11" round are not going to be x inches deeper.  In my experience, the 11" coil seems optimal from a performance standpoint, all things considered. The only real way to know is to do empirical measurements (i.e., real world performance experiments).  

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2 hours ago, GB_Amateur said:

I know you've said this before but I'm wondering what this is based upon.  Is it theoretical or found with measurements/experience or ??.  My limited measurements have indicated depth for USA pennies and nickels goes as the geometric mean (square root of the product of the two axes) so dependent upon both.  Other factors, espeically ground mineralization, can be large contributors as you and most(?) readers know.  I've not done comparisons in air.

I think this kind of started with me. Think 10” round coil vs 10” x 5” coil. Many novices assume 10” is 10”. I've gone out of my way for a long time to make sure people know they are not the same. To make it simple to understand, I told people to focus on the narrow dimension, and think of a 5” x 10” coil (I reversed the norm of using large number first) as an elongated 5” coil. Is that completely accurate? No. Surface area is probably a more accurate comparator. But that takes too much math. I’d rather people be conservative and be pleasantly surprised, than expect too much and be disappointed.

The most extreme example I can think of is the 3” x 18” Bigfoot versus an 18” round concentric coil in mild ground. The Bigfoot certainly gets more depth than a 3” round coil, but it’s a world away from an 18” round.

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