28ga teflon wire

[6666]

Here is a double-sided spiral I did in Easy-PC between code compiles:

[ATTACH]43710[/ATTACH]

It has 60 mil traces with 25 mil spacing, N=24, d(nominal) = 10" (25cm). I chose trace width/spacing to keep the overall ring @ 1" wide. With 2 oz copper the trace width is equivalent to ~27 AWG so the "gauge" and spacing are almost the same as the OP's specs. It would be interesting to compare results.

PCBWay quotes $209 (plus shipping) for 10 boards, so right now it's a little pricey to find out. It's something I've been wanting to play with for some work projects so I may do it anyway. Obviously you don't want to waste all that middle real estate so maybe make it a set of progressively smaller coils.

Thanks for the graphic, $209 is a bit prohibitive, if you decide to go ahead to help defray your cost I would be interested in one board thanks.

[Carl-NC]

Here is a double-sided spiral I did in Easy-PC between code compiles:



It has 60 mil traces with 25 mil spacing, N=24, d(nominal) = 10" (25cm). I chose trace width/spacing to keep the overall ring @ 1" wide. With 2 oz copper the trace width is equivalent to ~27 AWG so the "gauge" and spacing are almost the same as the OP's specs. It would be interesting to compare results.

PCBWay quotes $209 (plus shipping) for 10 boards, so right now it's a little pricey to find out. It's something I've been wanting to play with for some work projects so I may do it anyway. Obviously you don't want to waste all that middle real estate so maybe make it a set of progressively smaller coils.

[dbanner]

Actually, Green's flat basket coil is almost like a two layer coil. The windings have a vertical distance between them. At least it looks that way.

[6666]

Not White's, Tesoro Sandshark. Printed spiral has the drawback of higher resistance, which may not matter in some designs. Assuming 1oz copper, a 1mm trace width is roughly equivalent to 31.5 AWG. One improvement that Tesoro could make is to double-side the spiral. A double-sided printed spiral using 2-3 oz copper could make a dandy fast coil. Easy & exactly repeatable.

Doubled sided nows thats an interesting idea, thanks.

[6666]

Greens flat basket coil made with 30 awg kynar wire ~300uH samples at 8uS, but at that speed then detecting the coax feedline becomes a problem.

[Andi68]

He Looks like a Clown

[dbanner]

I forgot about the tesoro sandshark. I made wrong assumption.
Two layers spiral, hmm.
CNC flat coil, the guy made a second video:
https://m.youtube.com/watch?v=yj8OHuxBzAg

[Carl-NC]

Another observation is that the White's coil( I am assuming it's whites)...

Not White's, Tesoro Sandshark. Printed spiral has the drawback of higher resistance, which may not matter in some designs. Assuming 1oz copper, a 1mm trace width is roughly equivalent to 31.5 AWG. One improvement that Tesoro could make is to double-side the spiral. A double-sided printed spiral using 2-3 oz copper could make a dandy fast coil. Easy & exactly repeatable.

[kt315]

FASTEST.

http://www.geotech1.com/forums/showt...l-for-baracuda

[green]

absolutely bad and poor coil. not fastest. only trash.

What is the fastest coil?

[dbanner]

KT, it may not be the best, but it's far from the worst. There are few clues here to implement if I am making flat coil. The first is the pitch, the second is the inner diameter/outer diameter ratio( important for average depth and sensitivity to both large and small targets). I think with multiple strand Teflon, in a flat spiral coil with these ingredients would be superlative.
Only one way to find out.
Now can anyone say where Teflon multi-strand wire is best salvaged from? Is there a commonly known use for such wire? The local store doesn't have any. Seems a rare item in third world country.

[kt315]

In looking at photo of the original surf pi coil, I took note of the spacing between the windings(pitch?). It looked to be roughly half the diameter of the winding itself(maybe more). This give me suspicion of some relevance to the optimal space between windings as half the diameter of wire. But who knows, very little information exists about spiral coil construction.
Do you have Coil32 calculator software? It is yet another coil calculator you can download for free. It has a spiral coil calculator which is very good and gives many parameters.
The White's coil has 42 turns. Which is of no relevance to your coil, just interesting to know.
Another observation is that the White's coil( I am assuming it's whites), the inner diameter looks to be half the outer diameter. This must have some significance, as the ratio is same as a standard concentric coplanar arrangement.

absolutely bad and poor coil. not fastest. only trash.

[green]

The difference in specs between the two coils( inductances, capacitance) seems quite small, only the SRF has a small spread, so have you drawn any conclusions as to why the flat basket perform a little better? Just a few puffs can make measured difference? I wouldn't have thought so.

I'm just trying to learn. Have read spiral coil is fast but adding shield makes it slower than other winding methods, not what I've found. Most of the time I have more questions than answers. I don't know why the overshoot, looking like the coil is underdamped or why the overshoot is different between the two coils. The flat spiral has a lower circuit resonance maybe some of the reason.

Added lead length and Tx circuit capacitance are higher than coil capacitance.

[dbanner]

The difference in specs between the two coils( inductances, capacitance) seems quite small, only the SRF has a small spread, so have you drawn any conclusions as to why the flat basket perform a little better? Just a few puffs can make measured difference? I wouldn't have thought so.

[dbanner]

Green, I totally misread you table, the flat basket shows better performance.