5kg seems pretty light for a 40" toroid. I suppose the lighter the
construction the better, as long as it's strong enough to survive
handling. Some spun toroids dent very easily.
I think the John Freau 4" x 13" spun toroid probably weighs less
than 500 grams, I would guess 250-300. I managed to dent mine on the
trip to Cambridge :( I also have an 8" x 24" made from thicker
aluminium that I guess weighs about 3kg. If it were 40" it would
probably weigh at least 10kg.
Bill Wysock ordered what must be about the biggest spun toroid in
the history of electrical engineering, for his humongous Model 13M
coil. According to his site it was 8ft major diameter and weighed
275lbs. (125kg)
http://www.ttr.com/images/img-6.jpg
from the page http://www.ttr.com/model13a1.html
Steve Conner
http://www.scopeboy.com/
"how much does this toroid weight? i just want to make a comparison with my
homemade fiberglass 40" toroid