[Elecraft] k2 antenna connector

[Ron D'Eau Claire]

A properly installed BNC is extremely reliable in environments where the
cables are moved around a great deal. (There's a reason most test equipment
manufacturers chose BNC for RF ports on their gear where cables are
connected and disconnected constantly.) Of course, the "bayonet" type
connector is much faster to change than one with a lot of threads. 

The BNC will handle > 1.5 kilowatt of RF, so power isn't a consideration for
Hams using them at reasonable SWR levels. Good quality BNCs have a peak
voltage rating of about 500 volts. That's the same voltage rating as the
large SO/PL259 connectors(1)! Insertion loss and SWR will be very, very low
at HF. (It's < 0.3dB and SWR < 1.3:1 up at 1 GHz in a good quality unit such
as an Amphenol(2).) But, since most installations use a larger diameter coax
on high power installations, they also use a larger type of connector. 

For outdoor use, I've yet to see a connector I'll trust by itself to real
weather. I've done a lot of work on large ships, so when I talk about "real
weather" I mean hurricane-force winds blowing salt water around! In that
environment, most of the HF equipment I've worked with used SO/PL-239
connectors. Yep, the "UHF" connectors developed by Amphenol back in the
1930's that we find on the back of our KPA100 amplifiers. You'll still find
them on coax feeding HF antennas on ships of all sizes. I never saw a
weather-related failure in one that was properly installed, but it requires
a little more than just soldering a connector on the line. It is true they
are *not* weather proof, so when "properly installed" they are coated with
something like coax-seal. That's a material that comes in rolls like tape,
but which after being wrapped around the connector can be molded like putty
to form a water tight seal. A layer of conventional tape on top of it
finishes the job.

If/when it comes time to remove the connection, one uses a knife to cut
through the coax seal "jacket' around the connector and cable, then it is
peeled away from the connector and cable inside. Inside will be the old coax
and connector clean and shining bright and pretty just like the day it was
put on,  even though it many have been on there a couple of years and the
rest of the coax may be starting to look like something pulled out of an
ancient archeological dig.

I'd not trust a normal connector to *any* outdoor weather, since a little
water will cause instant trouble and water has a way of finding itself in
small cracks even without a hurricane force wind behind it.  

Ron AC7AC

1) http://www.amphenolrf.com/products/uhf.asp

2) http://www.amphenolrf.com/products/bnc.asp