[Elecraft] N fittings
Ron D'Eau Claire
rondec at easystreet.com
Mon Feb 14 19:34:28 EST 2005
Geoff, GM4ESD wrote:
Quite agree Vic, which is why I said "unprotected" !! There are a lot of
photos around (e.g. ARRL handbooks) that show bare PL-259s. Vaseline under
tape does a good job but not as "clean" as your method.
--------------------------------------------
Quite right! The key to the success of ANY fitting, including the 259
series, is in keeping them *out* of the weather. With the right materials,
that's not hard to do no matter where the connector is used.
When I last worked on large ships (in the early 1990's) the 259 series
connectors were still very common on HF and many VHF antennas. These
connectors were in weather no land-based Ham station ever saw unless it had
survived dozens of hurricanes and wind-driven 75 to 100 mph ice storms. In
addition to wind, water and ice, the systems were sometimes subjected to
corrosive stack gasses. Some antennas are mounted high on the funnel where
they'd get bathed in the stuff coming out of the engines as it swirls around
in the wind. All I can say is that no one in their right mind ever crawled
up there with the engines running without a full breathing system on. When
those gasses mix with the moist sea air, they form acids that can eat holes
in steel.
When the connectors were properly protected, unwrapping them after years in
that environment would involve peeling off layers of salt-encrusted,
weather-beaten coax seal and tape to reveal connectors as pristine as the
day they were installed, even though the reason for taking them apart was
often because the coax cable or the antenna itself had disintegrated in the
hostile environment.
Perhaps some of the other connector types are more forgiving if they find
themselves exposed to the elements, but I'd recommend putting one's effort
into keeping the connectors "out of the weather" by proper protection before
switching to more expensive types.
Electrically, there is no reason that I've ever seen documented to avoid the
259 series for work under 50 MHz. I know some RF engineers who don't
hesitate to use them in critical applications as high as 200 MHz. The losses
in the 259 system are miniscule and the "impedance bump" completely
negligible through the HF spectrum at the very least.
Ron AC7AC
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