[Amps] Re: compact coils...

[Roy Koeppe]

Marv talked about:


  "The 160 meter portion, even employing a reduced diameter conductor,
requires almost half the total space in a Pi-Coil.

  Has anyone ever seen a multilayer approach to this portion of the
coil?  For instance 3 layers spaced 1/4" apart radially.

  Five turns of #8, space wound 5 TPI on each layer 1" wide at a 2.5"
average (2" - 2.5" - 3" layers) diameter would provide something in the
vicinity of 17 uH.  This is approximately double the inductance of the
same amount of wire wound with at the same pitch in a single layer.

  It might take a bit of creativity to wind but, with a suitable form,
it could be fabricated starting with the innermost layer at the output
end.

  This approach would increase the interturn C somewhat but, I doubt if
that matters all that much on the "Topband"."

73 & Good evening,
  Marv WC6W

Hello Marv,

The early DX-100s used a honeycomb-wound 160 M inductor on a ceramic
tube form. I think the wire gauge was #14, cotton covered and doped
heavily. It was very compact. Now a days, I'd consider using a powdered
iron toroid for the 160 M portion of the pi net.

73,    Roy    K6XK