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








thanks

"ml" schreef in bericht
...
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.

Over time any viscous substance will rinse off.

Whatever happened to self-vulcanising tape?

73 - Gerard - PE1OUD

On Thu, 20 Aug 2009 07:16:31 -0400, ml backed into a tree
whilst ridin inna park then 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








thanks

Several things...There are silicones that have a non-acidic curing
process. They take longer to set and stay soft for their life.
That said, unless you have metal that is about the same thickness as
aluminum foil there is no way standard silicone is going to damage it
in 20 years or so. Yes I have been working with GE silicones for, oh
35 years or so.

Dan N9JBF

On Thu, 20 Aug 2009 07:16:31 -0400, ml wrote:

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

Unless there's something you're not telling us about your operating,
there will be little or no risk of "arc over/breakdown" at the center
feedpoint.

Locate some 'aquarium grade', non-acidic _silicone_ "goo".

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
* Killfiling google & XXXXbanter.com: jonz.net/ng.htm

On Aug 20, 7:16*am, 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

If you're worried about moisture getting into a coaxial feedline, I
wouldn't settle for anything less than Coax-Seal (mastic tape) for a
long-term hi-power installation. Proper installation of the coax-seal
is very important, randomly gooping gunk around won't help much.

Don't worry about exposed connections to/from antenna wire. Just keep
the moisture out of the coax.

If you're feeding with ladder line, I don't think there's anything
that has to be waterproofed at all.

Some people like to spray with clear acrylic to keep things shiny but
I don't think this will hold up forever in the sun, and it does
nothing electrically, and might become a minor pain that you have to
scrape off in case of modification/repair.

Tim N3QE

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.



--

73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

thanks to those that replyed from the few that responded it would
seem that the silicon would be RF safe at full legal limit

great


thanks

to those that asked if i was concerned with mositure not
specifically no, the silicon will take care of that


nor was I concerned with the silicon by itself causing damage
the non acidic stuff has treated me well.


thanks much




In article ,
What me worry? wrote:

On






thanks

Several things...There are silicones that have a non-acidic curing
process. They take longer to set and stay soft for their life.
That said, unless you have metal that is about the same thickness as
aluminum foil there is no way standard silicone is going to damage it
in 20 years or so. Yes I have been working with GE silicones for, oh
35 years or so.

Dan N9JBF

ml wrote in :

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

Some of the non-acetic cure silcones are water based, and do not make
good insulators for some days after application... so in that case, apply
them well before you intend using them, and don't adjust the antenna
until the sealant has cured.

In my experience, those sealants have not degraded when they become wet
in service, so it appears a temporary issue until they cure.

Owen

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.