Sat Tel GK

[skidoo]

I'm stuck on three, any help gratefully received
34a Ancient Greek festival and contest in music and athletics ?G?N
3d Unit of perceived loudness equal to 40 phons S?N?
57d Trade mark consisting of cogs and toothed rings to draw intricate patterns ?P?G?A H is it spirograph?

[sarumite]

34a Agon

[pbeach]

3d sone

[sarumite]

3d Sone

[pbeach]

57d is more than likely to be Spirograph except your letters don't seem to match

[skidoo]

Thanks for all your help - it is spirograph, I had not put enough letters in

[BigDave44]

... and for all those that had forgotten what it looked like :

http://en.wikipedia.org/wiki/Spirograph

[chrispybacon]

34a - agon