There should be another part to this discussion that I have not yet seen
mentioned. Coefficient of Thermal Expansion.
If the connectors are water tight/air tight, then in theory no taping of
connectors should be necessary if the connections are all
electrically/mechanically sound and very tight and no large physical
stress in placed on them. Furthermore, if tape is used and water
manages to get in, then it can potentially be sealed which over time
could create problems. But changes in heat/humidity can cause
condensation INSIDE the wraps anyway. So not using anything to wrap the
coax/connectors would allow immediate exposure to the elements and
simultaneously allow for moisture drainage away from the
coax/connectors.
But none of that addresses HOW and WHEN those physically tight
connections might become less tight. Enter Coefficient of Thermal
Expansion.
We all know that various metals get hot faster than the outer jacket of
coax, in response to direct sunlight and hot ambient temperatures in the
Summer. Conversely, we know that objects (like connectors) will shrink
in size response to the cold more than coax will shrink because of
differences in the Coefficient of Thermal Expansion (the reverse of how
they all expand with an increase in temperature).
Because connectors will shrink more in response to colder temperature
than coax will, a tight connection will begin to loosen and will allow
for water to get in. This is especially true in Winter in more Northern
climates.
So that "waterproof" connection becomes non-waterproof. And if water
can get in, ice can form and expand the gap and damage the the coax or
connectors or both. By using tape and sealant we are already protecting
against that.
But note that this is already happening anyway in microscale because the
coax jacket and the connectors are neither perfectly smooth nor exactly
the same shape, so there are already tiny ridges and depressions on the
surfaces of the coax jacket and the connectors that are allowing air and
moisture to get in even though you can't see it. But these tiny gaps
can easily be seen under an electron microscope even though is not
visible to the naked eye. Bottom line: Pro or not, you really should
use some sort of quality tape/wrap anyway.
73
Bob, KQ2M
On 2024-03-10 11:15, Steve Maki wrote:
You may have a different definition of "pro" that others do. Is it just
the broadcast industry that utilizes "pros"? That's another subject for
discussion.
It's true that modern connectors are theoretically weatherproof, and I
do not weatherproof the many 7/16 DIN connectors on my own ham station,
whether they are on Heliax or 3/8" RG8 stuff.
But in my (dare I say it?) professional work, our customers (AT&T,
Verizon, T-Mobile, etc) require it. Until recently it was always
tape-butyl-tape. Nowadays it's custom rubber boots...but still, it's
external weatherproofing.
-Steve K8LX
On 03/10/24 7:04 AM, Rob Atkinson wrote:
I'm pretty certain that the pros use butyl mastic
The "pros" don't use anything because they don't use UHF connectors.
They are working with Heliax, waveguide, or ridgid line and the lines
are often pressurized. Connectors made for those kinds of lines don't
require all these wild methods involving tar, and tape and do more
harm than good by sealing in moisture.stevek@jmr.com is correct.
The ideal method is nothing. If you have a feedline run laying on or
under the ground that's subject to flooding, then elevate the
connections. I'd want to do that anyway to make it easier to
troubleshoot. I tried all the tape, tar, grease, and so on a few
times early on and realized it was heading in the wrong direction.
73
Rob
K5UJ
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