I believe in mult-layer versus single-layer coils there are 2 factors
having an opposite effect :
1. A multi-layer coil needs less wire for the same inductance = less copper
2. A multi-layer coil will suffer more from the proximity effect (the Q of
coil is degraded by the proximity of the turns to each other, in a single
layer coil each turn has on 2 'neighbour' turns, in a multi-layer coil this
can be up to 8 'neighbour' turns)
Since in a single layer coil the proximity effeect can be minimized by
spacing the turns (spacing = wire diameter seems a good compromize) I
assume that in a multi-layer coil Q can be improved by spacing the layers
usng a low loss dielectric material.
Further I believe to have read somewhere that higher Q's can be achieved by
winding a multi-layer coil in 'chambers'.
73, Rik ON7YD
At 01:46 31/10/01 +0100, you wrote:
concerning multi versus single layer coils I have been informed by DJ2EY who
employs two coils of different diameter as a variometer that the Q of the
coil is less when the smaller coil is fully immersed into the greater one.
seems that the metal of the inner coil increases the loss of the outer
possibly vice versa).
Therefore when a high Q is needed, a single layer coil would be the better
73 Ha-Jo, DJ1ZB