Surf pi 1.2 Coil Shield

[targetdown22]

Hello, i am building a coil for my Surf PI 1.2 but i don't know if the shield is really necessary, i made 1 test coil without the shield it was working well and after the shield the coil is pretty bad.
If i don't put shield what can be the concequences ?
And a last thing with the coil calculator, do i need to put the inside radius of my coil housing or i put the middle of my coil shield like where the final coil will stay ?

[Qiaozhi]

Hello, i am building a coil for my Surf PI 1.2 but i don't know if the shield is really necessary, i made 1 test coil without the shield it was working well and after the shield the coil is pretty bad.
If i don't put shield what can be the concequences ?
And a last thing with the coil calculator, do i need to put the inside radius of my coil housing or i put the middle of my coil shield like where the final coil will stay ?

What material did you use for the shield?
Did you leave a gap?
You can get away without a shield if your sample delay time is fairly long, but in general you should use one. It also helps to eliminate some EMI, as well as its usual purpose as an electrostatic shield.

The Coil Calculator uses the inner radius of the coil bundle.

[targetdown22]

First thank you for you answer i really appreciate.
The material i use as coil shield is aluminium tape.
I will detect underwater not close to electric cable etc in the mountain mostly, is it still necessary ?
Making a shield add a lot of difficulty to the project.
By coil bundle you mean what exactly ?
Sorry my english is not perfect and i have difficulty to understand this sentence.
Thank you again

[targetdown22]

And an other question, The surf pi 1.2 coil inductance should be close to 500 uH ?

[Ferric Toes]

First thank you for you answer i really appreciate.
The material i use as coil shield is aluminium tape.
I will detect underwater not close to electric cable etc in the mountain mostly, is it still necessary ?
Making a shield add a lot of difficulty to the project.
By coil bundle you mean what exactly ?
Sorry my english is not perfect and i have difficulty to understand this sentence.
Thank you again

Have a look at the other thread on using charcoal for a shield. I have just posted details of woven fabric shielding tape that will work fine on a Surf PI coil. Also there are pictures of how to make a good PI coil shield using this tape.
Aluminium tape is no good as it is much too conductive and even with a gap, will give a large signal of itself.
I use the word bundle. It is the diameter of the cross section of the coil. If you cut through all the turns and still hold them together, that is the bundle, the diameter of which can be measured by a circle that encloses them all. Like a piece of rope 10cm diameter, that is a measurement of the bundle of fibres.

Eric.

[targetdown22]

Thank you for you answer, but do you think in my situation that the coil shield is necessary ?
I will certainly not go detecting on the beach only freshwater (river) and no phones etc close.
thanks

[jladre]

Thank you for you answer, but do you think in my situation that the coil shield is necessary ?
I will certainly not go detecting on the beach only freshwater (river) and no phones etc close.
thanks

targetdown22 i'm also a beach hunter. Believe me that coil need shield if use in wet sand. Without a shield it will produce sound every time the coil hit the wet sand, it is also picking up those interference around. But if it us use below water/submerge in water then shield is not needed. But a shielded coil is always better.

[targetdown22]

Thank you for you answer, i will use the detector exclusivly underwater (freshwater) i got a Minelab Explorer SE with 15x12SEF coil for beach etc etc, i love my minelab but i can't go underwater that's why i build the surf pi 1.2.
so if i go only underwater no need of shield then ?
thank you

[jladre]

Thank you for you answer, i will use the detector exclusivly underwater (freshwater) i got a Minelab Explorer SE with 15x12SEF coil for beach etc etc, i love my minelab but i can't go underwater that's why i build the surf pi 1.2.
so if i go only underwater no need of shield then ?
thank you

I have no experience in fresh water but my saltwater pi the surf pi 1.2 and baracuda doesn't have shield. They work great as long it is underwater.

[jladre]

i love my minelab but i can't go underwater that's why i build the surf pi 1.2.

I love mine too but i'm so eager to make it waterproof like this.. its really time saving than using pi.

[targetdown22]

I saw this pictures too, i would like to do the same but i don't feel it good to go with a machine i paid 500$ inside the water lol anyway i will not use coil shield and i will see how it performs.
Thank you a lot

[targetdown22]

without shield the coil work pretty well my detector is almost fully built, i bought tonight the Minelab Excalibur 2 i hope it is a good detector because it cost a lot lol thank you guys tomorow i hope i will be able to test my detector i will give a feedback if it work well.
Thanks again

[jladre]

without shield the coil work pretty well my detector is almost fully built, i bought tonight the Minelab Excalibur 2 i hope it is a good detector because it cost a lot lol thank you guys tomorow i hope i will be able to test my detector i will give a feedback if it work well.
Thanks again

I have an excalibur 2 also. Its very good detector if its working well. Im waiting mine to send back dmfrom dealer after sending it for faulty threshold. Just used it for about 30 times and problem exist.

[targetdown22]

The knob broke or the potentiometer?
I heard that knob break very fast

[jladre]

The knob cap(the yellow on the top) will easily fall. The problem of mine is the threshold sound is so loud even at the lowest setting. If is is not the potentiometer they suspect that it is a coil or power supply problem.. Good to you if yours will last longer without problem.