If you are considering reworking a 40-2CD, there are a couple things I would
recommend since I have been through this sometime ago.
Inspection showed that every loading coil had corrosion on the screw
connecting the coil wire ends to the elements. I cut away the shrink tubing
over the end of the loading coils and replaced the screw with a Stainless
Steel screw and put new heat shrink over the whole assembly and sealed the
ends of the heat shrink with Silicone Glue before shrinking it. I'm not a
mechanical engineer, but possibly a better solution would be to run a bolt
through the element; then again, maybe not. It has been up for over 25
years now without any intermittent issues. There may be a better solution to
sealing the heat shrink as such as the self-sealing heat shrink.
What seems to have happened is that the original heat shrink didn't seal
well enough, so moisture was able to get into the coil.
Another thing I did was strengthen the elements with inside tubing. The
elements especially seem weak close to the boom. Even my reinforced
elements have had a slight bend in them for some time due to middle America
winds.
Dave Leeson, W6NL did an article on strengthening the 40-2CD,
http://k7vc.com/402cd.html
Another article is "Simplified Strengthening of the Cushcraft 40-2CD" by
N4KG in the Mar/Apr issue in of NCJ, 1994.
Also, put locktight on the nuts holding the capacity hats to the elements.
I also made a new mounting bracket that will allow the antenna to tilt up or
down so one can get to the element attachment points to remove an element
for repair.
NOTE: If lightning hits an element, the loading coil will disappear. No
cure for this, but the tilt mounting bracket will become your best friend.
Good Luck.
Jim - KR9U
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