Best 5x10 coil for TDI SL?

[goldchaser3]

Has anyone done a direct comparison between the 5x10 DF Jimmy coil and the 5x10 Mono Razerback coil? (Not the folded 8 RB).
I have the 7.5DF but looking to add a narrower elliptical for my TDI SL for prospecting in the California Gold Country and don't know which one to get. I've heard that White's (Jimmy Sierra) may be better quality and/or "tuned" (whatever that means) to the machine, but I also own one RB coil (10x14 Mono) which goes very deep and is very light and has worked great for me. All comments appreciated. Thank you!!!

 

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[goldchaser3]

Thanks Reg. If the 8-1/2x11 coil exhibits the same characteristics I was also thinking about wrapping the first 1-2 inches of the cable with an epoxy putty to keep it solid. Thoughts on that?
It seems to me to be a design issue. If slight movements of the cable around the base at the coil are known to create false signals, I am wondering why they (the manufacturers) don't do the same thing = physically 'firm' the first few inches. Is there some kind of performance issue that would keep a coil builder from doing that?

 

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[Reg]

I tried the wiggle test by wiggling the coil pigtail on my White's DF 7 1/2" coil and also on one of my new special coils I just built that is overly sensitive and I don't get any false signals. You might try the same on your White's coil and see what happens.

I suspect your White's coil will not show any false signals.

Let us know what you find out.

Usually, this wiggle test you displayed indicates the coil is detecting the wire shielding. Again, using wire with served shielding will eliminate or at least minimize this problem. So, it is not the norm.

I forgot to answer your question so I edited my post to add this info. You can stiffen the wiring down at the coil using different methods. Personally, I would use something other than epoxy, like maybe self fusing silicone tape or even 3:1 heatshrint tubing large enough to go over the connector. You could even use plastic tape as a temp fix to see if it helps.

If the pigtail is stiffened it should help minimize any lead detection. Again, the only way to know for sure, though, is to try it and see.

Reg

 

[goldchaser3]

TDI SL coil update:

I received the new 8-1/2x11 mono coil from Razorback. This one has a new cable-type but still makes a small falsing signal when the cable is wiggled. I am going to keep this coil but just wrapped it (the cable) with "Wrap-Fix" tape to make it firmer next to the coil, per Reg's recommendation. I tested it in my back yard and it works well.

BTW My 7.5DF didn't false at all when the cable was wiggled near the coil. White's must be using a superior cable. I also tested my 10x14 mono RB coil again, and it did false a little.

I had dug up my gold nugget already, so air-tested the 7.5DF, 10x14 mono RB and the new 8-1/2x11 mono RB.
I tested my 4gm nugget, $5 (2001) gold coin, 1949 nickel and 1954 quarter.
The 10x14 was consistently 1" deeper than the 8-1/2x11, and the 8-1/2x11 was 1" deeper than the 7.5 DF. These results were more what I was expecting. The 10x14 also outperformed the 12"DF when I had it, but have since sold it. My guess is that the 8-1/2x11 is close to the 12"DF with regards to depth.
I like the shape of the 8-1/2x11 along with it's greater depth over the 7.5DF. The front end of both coils are almost identical so I think I will be able to put it just about everywhere I could put the 7.5. I also believe the mono will handle ground mineralization a little better and run even more quietly, although with the TDI SL it's already very smooth.
Thanks everyone for your guidance!

 

[Hard Prospector]

Strong work and persistence.

 

[Miner John]

Hi, guys,

I'm Miner John, the new owner of Razorback coils. I just joined this forum and I'm sure glade I did! I really want the feedback about my coils. How else can I learn about problems and make the changes to my products?
I started building all of the coils using the recommended supplies of the previous owner. I now see that I will be changing the cable that I'm using to the one Reg talked about on an earlier post. Thank you Reg.
I want to make a product that I'll be proud to sell and that you guys love!

Miner John

 

[Miner John]

There are different types of cable that can be used for coils. What usually is the big difference is the shielding type and one of the best is something called served shield. The more conventional shielding is more of a X or cross shielding that is often detectable while the served shielding is much finer wire wound around the inner core. Generally, this served shielding isn't detected by most PI's.

It sounds like the coil you have uses the X type shielding. If this is the case, then the cable should be run straight up the lower shaft at least a ways and be relatively snug near the coil to avoid detection. If you haven't sent the coil back, you may try this setup to see if the falsing is minimized.

I am puzzled by the depth difference. I would expect the 5 by 10" coil to be competitive with the 7 1/2" Whites DF coil. I wind my own coils and mine are quite competitive depth wise.

Reg

PS: Building coils for the TDI isn't that difficult and if they have the proper turns and good shielding then all that are relatively the same in size should have equal depth. Now, because noise can have a major impact, any comparison of coils should be done away from any noise sources if possible or at least done almost immediately in succession and not done on different days to avoid wide noise variations.

How much can noise influence a coil test? Well, I have tested the same coil with a nickel as a test target on different days and had as much as a 2" to 3" difference in air test.

Hi, Reg,

You talk about the serve shielded cables. I looked into it for my Razorback Coils and there are many different brands and styles out there. Any suggestions?

Miner John

 

[nuggetshooter323]

You might try sending him an IM to get his attention, he may not check this thread for several days.

 

[Reg]

Hi John,

GC3 is right, I don't check this forum every day. Too many other projects going related to detectors to look at all the forums regularly.

I responded to your email before I saw this post but I will add a little more here. As I mentioned in the email, I use Mogami coax. So far I have not had any problems with it.

You might call the various companies and request a sample of their coax to see if it fits your needs rather than try buying a little of each. Most companies will be happy to provide a sample.

Check for flexibility, stranded center core at least 24 awg in size and most important, make sure there is no response from the wire shielding or the core. Some if not most provide specs that include expected life under flexing conditions. This is important also.

Regardless of what brand you start out with, I wouldn't buy that great of an amount until you are sure it will work well for you. I remember one time Eric Foster bought quite a bit of dual coax (for making DD coils) and found out the wire would break quite easily. Eric mentioned he ended up using the wire for extension cords for his guitar, if I remember correctly.

BTW, I still need to find another good brand of dual coax. I am using Mogami S video cable for that also, but don't like the fact the outer housing isn't round and bigger.

Reg

 

[Miner John]

Thanks Reg. I really want to fix this cable issue soon! I'm currently using a Premium S vidio cable for my DD coils as well. It doesn't seem to have any negative issues so far! Knock on wood!

Miner John

 

[Reg]

After finding out what cable was used for the coils, and giving some thought to the situation, I understand why there was some detection of that coil cable's rapid movement, especially by the TDI SL. First, as I mentioned before, the SL is slightly more sensitive to small gold than the other TDI's. This is the result of a small mod added to the SL that isn't in the other units.

So, the SL will show more sensitivity to any detection of coil lead than the previous models produced.

Now, the cable used was most likely selected for its core size and potential durability. As such, it would have the potential to be detected easier than other cables that could be used. In simple terms, the selection of the cable was most likely the result of trying to do the right thing for reliability and durability.

I heard it was recommended that the cable be tied down to the lower shaft so movement would be minimized. This makes sense and would most likely take care of any casual movement. Thus, the problem most likely would be solved, especially if there was tension on the cable. Such tension would have a tendency to not allow the vibration that could occur with a free cable.

Now, with all that above said, I wouldn't call the ability to detect the cable a design flaw of the coil, especially when using the SL. I am sure the cable was selected well before the SL was initially produced. What I don't know is if the other TDI's ignored the cable movement that was displayed in the video. I suspect it wasn't detected or if it was the signal was minimal.

So, again, I wouldn't describe the cable use a design flaw but the signal heard on the SL was mainly the result in the design change in the SL. I also think any rapid vibration which is what would produce the greatest response could be minimized by reducing the potential motion of the coil pigtail coming out of the coil housing. This could be done with some type of sealant similar to silicone sealant but electronically safe and then adding some heatshrink to further stiffen the pigtail. My guess is this would eliminate or almost eliminate the problem as displayed.

Relic hunters who advanced the delay would never even know this condition existed since a small delay change would most likely eliminate any signal. Thus, gold hunters would be most likely the ones to run into this condition.

Reg

 

[Brivic1]

Well now, after getting around all of the above: I tried a piece of " springy plastic fork " at the pigtail of my old VSAT. Taking out the centre tine of the little fork . There had to be room for the changing of angle of the coil [ naturaly ] so it was a bit of a challenge. The chord was tied-off with electrical tape at 3" from the bottom of shaft and the testing plastic was below and wrapped in the same manner to keep enough tension on the chord.I I taped a small pce. of HD plastic to the shaft to hold out the fork. It was a cheap way to keep it tight but not in anyway saleable... It took the noises that came with the hitting brush and rocks, away. Looked silly being pink/ yellow in color.
I had asked MinerJohn about those noises , a few times over the years, but this last month I got annoyed enough to try something.
I still think that the factory coil is in need of a take-apart and re glue or epoxy of the inside wiring.
All the best, Bri.