Toroids
Here's some thumbnails of my early Toroid construction before I migrated to O. W. Landergren products
24" o.d., 7" chord
The 1st three photos are of a toroid constructed with 7" diam. aluminum ducting from Home Depot, an al plate and al tape. This was constructed in 2000 and the photos were taken and posted here tonight (Dec. 16, 2004). Photos of this toroid in action are on my 1/4 wave page. I've also constructed a larger one and neither have exhibited any untoward arcing and the tape (also from Home Depot) has shown no sign of 'letting go'. There were some light red logos printed on the al tape about every 5". I used acetone on a rag to remove them.
However, these are as fragile as 'eggshells'. Well, eggshells are probably much more resistant to incidental 'bumping' and the concurrent denting. The best way is to purchase a professionally made toroid, perhaps from O. W. Landergren. By the way, for those who don't know, they have been making toroids since 1927 as an early G. E. power-plant was situated 20 miles from their front door. They are among the the best, bar none.
For a comparison, this one cost me under $100.00. A comparable O. W. Landergren toroid, as a one-off, would cost around $300.00. There are a few methods to make one of these look halfway decent (it takes four hands to stretch a length of ducting) and they are worth the effort.
The last image is a beautiful cu toroid made by John Freau around 10 years ago.
- 5-22-11