On 6/21/2011 11:13 AM, Jim Lux wrote:

It does matter. What you really don't want is something that changes.
Either always connected or always insulated is what you want.

Dead right.

This seems to be one reason why yagis at HF tend to be grounded elements
and at VHF and up tend to be insulated. At HF it's fairly easy to get a
low resistance with fairly low impedance change over a few years.
That's harder to do at VHF especially with through the boom uninsulated.
Hence through-the-boom or over-the-boom insulated at 2m and up.

I've built many 6m beams with no correction added and using simple
homebrew U clamps. I have seen little discernible difference in their
performance from predicted. Of course I shouldn't except perhaps in the
side nulls. And they seemed about right. One small confirmation was
the SWR curve also matched predicted.

Anyway, the problem with connected is corrosion. Can only slow it down.

tom
K0TAR