Stuff a wad of fiberglass insulation in each one? But if you make the
plug too long and it gets wet, it will add some weight to the ends of
the elements. Foam in insulation around a small tube instead of a
rod, so you don't have to withdraw the rod? (That "Great Stuff"
polyurethane foam is really sticky!)

If it's really an organ-pipe or whistle effect, that should do it. If
the mode is a bending of the elements, you need some different damping
for that. I know a company that specializes in vibration damping in
all sorts of situations that could undoubtedly help you--for a price.
But if you think about the modes, you can probably take care of it
with something like Nylon twine between the elements at the right
points. Expect to have to replace it occasionally because of UV
exposure, or use UV-stabilized line.

Cheers,
Tom


(Fractenna) wrote in message ...
One solution (I have seen work) is to squirt 'Great Stuff' into a foot or so of
the open end, and let it form around a skewer. After it dries, pull the skewer
out for the drip hole.

Great Stuff (comes in a can) is a foam insulation, much like styrofoam, used to
seal window joints, and so on. It is transparent to RF below about 3 GHz

When you squirt it in it hardens up and suppress the driven oscillations.Bummer
that you have to pull down the antenna though...

Also, some folks use nylon rope in the elements as a damper. Perhaps someone
who has succeeded with that will respond.

Best of luck on this or other solutions.

73,
Chip N1IR