[HBR] Fiberglas tubing for coil forms?

[Shoppa, Tim]

There's a zillion formulations and grades of fiberglass out there, but the ones intended for electrical use (esp. things like G-10) are truly excellent for this sort of application.

The standard test is to put the plastic in a microwave alongside a glass of water, and run the microwave for 20 seconds. If the form gets hot, it's absorbing RF and may not be a good choice.

IMHO, the best choice among readily available plastics for coil forms is polycarbonate. It is incredibly easy to work (does not crack like acrylic / plexiglass)cheap and easily solvent-welded. Available in sheets, tubes, etc. If you don't have a local plastics supplier I recommend McMaster-Carr ( http://www.mcmaster.com/ )

I use polycarbonate for all my "homebrew" coil forms and especially plug in coil sets. A picture  of the 80M link coupled tuner coilset and tuner is on the web at:

http://www.traliing-edge.com/~shoppa/linktuner.html

Tim N3QE