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Went out to an old school site that had 3 schools thre. on 1889, 1924, 1937. All torn down by 1978, My new 950 coil is able to handle RX 15, Tx boost on. The first 10 minutes I hit a 1944 merc at 6 inches. It hit hard like it was only 3 inches. I cannot believe how stable the 950 coil is. It is not chatty at the max setting. It pinpoints right on it. I believe it could hit a quarter coin at 8-10.If you don't have one of these coils you should.
I wished I had one for the last 2 weeks while hunting beaches in Florida. The D2 was very unimpressive and ended up using then10x 12 with some success . I will have one hope before to long.
HH
A lot of people mention that the 950 seems to be more resistant to EMI than the standard 10DD coil. I have not seen any of these reports relative to the spider, probably because it has not been around so long.
I have been looking specifically for comparisons of the old 950 "flying saucer" vs the new spider in terms of EMI susceptibility, or if the more open case design would have any effect on that.
A lot of people mention that the 950 seems to be more resistant to EMI than the standard 10DD coil. I have not seen any of these reports relative to the spider, probably because it has not been around so long.
I have been looking specifically for comparisons of the old 950 "flying saucer" vs the new spider in terms of EMI susceptibility, or if the more open case design would have any effect on that.
Re: "What part of same coil different housing seems to escape you guys?.."
Because coil housing materials, particularly the conductance of the material, and the shape and thickness of the housing around a coil are obviously very important factors in determining it's susceptibility to EMI.
I don't doubt what Carl has said regarding the new 9" Spider vs the 950 Eclipse, but as someone who owns/uses both coils, there are other differences which several users including myself have highlighted in previous/other posts 9" Spider Eclipse on this forum!
Both coils are concentric coils. Concentric coils are less affected by EMI than DD coils. The 10" coil is a DD coil. The old 950 coil was a solid filled coil and therefore could not be rebuilt. The 9" spider and 10" can be rebuilt and are not epoxy embedded and are therefore lighter. According to Carl (former lead engineer) the 9" and 950 coils are identical electrically.
Therefore, according to Whites except for physical differences there should be no performace differences such as resistance to EMI or depth..
I only have the 950. I haven't taken it apart, but if it is solid filled where the spider has an air gap, I would think that might be significant.
Also have to consider what happens when you put a nearly 5 foot long metallic pipe into the active search cone. Compensation for the coil shaft is done by various means a.k.a. "nulling". However the old design puts the shaft at the edge of the coil, whereas the new design places it closer to the center. With the old coil, the normal angle of the search coil while searching puts the shaft almost entirely out of the active field, so the rod (and any EMI it might be picking up) should be less of an intrusion.
But what I said is speculation. It would be interesting if someone who has both coils could do a side by side. EMI is real subjective, but one very rough way to test is the put the MD in a noisy environment, crank up Sensitivity till it goes crazy, then drop it down to stability, and note the setting.
The question between the spider coil and the 950 is all about stability of the coil windings. The 950 is fully encased (why it is not repairable) and the spider has the support "web" (hence the lighter weight). Don't have the spider coil but in my opinion the spider may be more prone drifting from the optimal null point between the tx and rcv coils becase of environmetal factors. I'm sure both coils work well it's just a matter of choosing weight or stability, but to say the coils are the same would be technically incorrect. I'm an electrical engineer and have built a few detectors (years ago) and wound a few detector coils and stabilty between the coupling of the tx and rcv coils is extremly important. That said i'm probaly going to buy a spider coil for my V3i, i've swung the 950 from my trusty xl pro and it can get heavy after awhie (still love that old detector). Now just need the snow to away happy hunting!
Well have fun with the discussion about the coils, I'm not an engineer so I don't have your expertise. Why not go to Carl's forum (Geo Tech) and discuss it with him. You might also try reaching him a First Texas.
What you said is similar to my thoughts. I am an engineer (but not EE) and all sorts of red lights and sirens started going off in my head when engineers were quoted as saying these 2 coils were exactly the same when you can tell just by looking at them from the shape of the housing and position of the shaft, and where the wires come into the housing that they are not.
I have not had the 950 long enough to say much about it, but my first impression after struggling with the DD coils for several years is that my V3i finally feels comfortable in its own skin.
My understanding is that the parents and grandparents of the V3i were developed with the 950 as "stock", so there seems to be a deep compatibility with that coil over the years. I did not buy a V Series until after everybody had jumped on the DD bandwagon. I have a whole closet full of DD coils, and I have never like the way they pinpoint, or their weirdly shaped search patterns with multiple hot spots, the way they blur the VDI, or their great ability to pick up the faintest bit of EMI from anywhere.
For the record, I have fairly mild soil in North Texas, so I don't "need" a DD like someone in Sweet Home or the mining regions might.