[TowerTalk] driven element center insulation

[Dave Sublette]

I just put up a 40 meter rotary dipole using leftover Telrex elements.  The center of the element is 1.625” O.D with a section of 1.5” O.D. tubing inside.  I had a friend turn down an Oak piece to 1.375” and inserted it to join the two halves.  I coated the Oak with epoxy to bond the two halves together and to try and keep moisture out of the wood.  I split a piece of schedule 40 PVC pipe and put it around each half, clamshell fashion, to insulate the driven element from the U-bolts used to hold it to the mounting plate.

My next project will be to build two, two element Moxon yagis for 40 meters.  I would like to use a split driven element.  Instead of Oak, I would like to find some sort of high strength insulating material in tube form to go in the center.  It would also have to be 1.375” O.D. because I am using more of the Telrex elements to build the Moxon.

What sort of material would you all recommend?  Telrex literature says they used phenolic insulation.  I’m guess there is a better material available after forty years.  I am hoping (but not very hopeful) that I won’t need stays on the elements if the center material is strong enough. 

As always, I look forward to the resulting discussion that this great group always supplies.

73,

Dave, K4TO