What type of wire is used to make a PI coil?

[Anonymous]

Say I wanted to build a 12.5 inch DD coil. What type of wire is used? How many windings are used? Thinking of building one for a winter project.

 

[Anonymous]

Look to use the Radio Shack wire wrap that is 30 gauge (50 ft spool) with a coating heaver than magnet wire. This will give you less coil capacitance than magnet wire as well as provide a small enough bundle to make the DD coil overlap practical in a coil shell. Also consider getting a 100 ft spool of 26 to 28 stranded plastic coated hook up wire.
For a point of reference, a 50 ft length spool will only allow you to use 18 turns or about 300 uH at 10.5".
The coil length depends on the specific PI design. There are a number of on-line coil calculatiors that will give you the number or coil turns for a given diameter and given inducatance in microhenries (uH).
One question though. What type of PI coil are you making; a high power with high coil current and thicker wire or a low power with lower coil current and thinner wire?
What are you coil housing constraints? Remember DD coils overlap and need to have enough room in the coil housing. Go to Hays (or Hayes) Electronics web site for DD coil shells.
Also, don't forget to shield the coils and insulate from each other at the crossover point.
Do a search on this site and the Geotech web site on the words "DD coil" and look for discussions about DD coils. There is a wealth of information on this topic.
I had the same question as you posed and researched these forums and was saturated with lots good information.
Eric and Reg can probably give you some much better practical advise about DD coil design and recommended wire size.
bbsailor

 

[Anonymous]

I'm going to use a coil cover 12.5 DD sovereign coil as a trial. I want a little better coverage with my Goldquest SS, thought this would work out nicely if I could get some info on the particulars. Can't seem to find that info on the DD coil. Could you send me a link possibly? By the way thanks for the input I'm just starting to understand some of the workings of a PI.