thanks Ian, that was very interesting never knew that about hot melt
and i have a some 'pro' hot melt guns really cool




In article ,
Ian White GM3SEK wrote:

ml wrote:
hi

Was going to make a center fed dipole, and wanted to put some (non
vinigar/acetic acid) Silicon goo on the center to waterproof.



Just wondering if this is typically 'ok' for full legal limit?


wasn't really sure if there would be arc over/breakdown or other
issues


Probably not, but hot melt glue is a better sealant and a better RF
insulator. Regular translucent hmg is amorphous polypropeylene, a
largely non-polar polymer which is a close relative to polyethylene. It
is free-flowing and very, very sticky while it's hot.

Tapes are excellent for waterproofing simple shapes like inline
connectors, because the tape can be applied evenly and under constant
tension. But the tails on the end of coax make a difficult shape to
wrap. The same applies even if you connect a plug to the socket on a
dipole center insulator. These more complex shapes make it difficult to
keep self-amalgamating tapes under the tension that is needed to make
them seal effectively.

Coax-Seal is good for waterproofing complex shapes because it is
moldable... but what are its RF insulating properties? I've never seen a
product data sheet that deals with this issue.

I've had cables and connections sealed with hot melt glue outside for 10
years. Some applications involve high RF voltages where the hmg is the
only insulation, and some involve very unfavorable combinations of
dissimilar metals. In all that time I have never had a single failure
involving either RF breakdown, water leakage or corrosion. Contrast that
with silicone or epoxy sealants which begin to deteriorate after 2-3
years in the rain and UV.