[Elecraft] BNC & SO 239

[Bob Nielsen]

The UHF panel-mount socket is the SO-239, however the mating plug is
the PL-259.

Bob, N7XY

On Wed, Mar 19, 2003 at 10:18:45AM -0800, Ron D'Eau Claire wrote:
> An SO-239 is the socket that goes with the PL-239 plug. They are often
> called "UHF Connectors" because they were often used in that service
> many years ago although they are not especially good above HF. The "239"
> series of connectors were developed in the 1930's for Amphenol for use
> with the coaxial lines that were coming into commercial use. They do not
> present a "constant impedance" and so reflections on the transmission
> line (high SWR) becomes an issue as the frequency goes up. For Ham use
> they are generally okay up through 2 meters.  
> 
> Early coaxial lines were quite lossy compared to what we have today, and
> larger sizes of coax such as RG-8 were used at 2 and 1-1/4 meters by
> hams to minimize those losses. BNC connectors are not suitable for use
> with the larger coaxial lines. I suspect that's what perpetuated the use
> of the larger 239 style connectors at UHF in spite of their higher
> losses. 
> 
> The BNC was a standardized connector system developed in WWII as better,
> lower loss, connectors were needed for higher frequencies. "BNC" stands
> for Bayonet (the type of locking mechanism)- Neil-Councelman (the
> inventors). Neil and Councelman did the design work that reduced
> reflections and made these connectors superior up through UHF
> frequencies. They also invented the variation used to produce more
> secure connections in aircraft called the "Type N", which is a BNC sized
> connector with a screw on collar around it to secure it better. 
> 
> So, in theory, the BNC is a superior connector electrically, although
> there is little or no practical difference at HF. The BNC is smaller and
> readily-available. I suspect that's why they become popular on smaller
> rigs. 
> 
> That BNC/SO-239 adapter you have is also excellent for connecting your
> K2 to a wire antenna if you have the KAT2 ATU installed. A banana plug
> will fit snugly inside the center hole of the SO-239, eliminating the
> need to buy another adaptor for that use.
> 
> Ron AC7AC
> K2 # 1289
> 
> -----Original Message-----
> i have an adapter for my k2 antenna to go from the bnc to a so 259 or
> 239 whatever will that work or is it for vhf?  i cant tell the
> difference between s0259 and pl 259 or it was something like that at rat
> shack.  what im trying to do is hook up the k2 to regular coax cables,
> never had a radio with a bnc connector other than my scanner ht.
> 
> john wt5y