[TowerTalk] Coax Connectors

[Bob Nielsen]

 From an Amphenol web page <http://www.amphenolrf.com/products/ 
uhf.asp>, although I don't think they got it quite right:

"Invented in the 1930's by an Amphenol engineer named E. Clark  
Quackenbush, UHF coaxial connectors are general purpose units  
developed for use in low frequency systems from 0.6 - 300 MHz.  
Invented for use in the radio industry, UHF is an acronym for Ultra  
High Frequency because at the time 300 MHz was considered high  
frequency."

Another web site <http://www.radio-electronics.com/info/antennas/coax/ 
uhf_connector.php> has a bit more to say (possibly the above was  
extracted from this):

"The UHF connector is a coaxial RF connector that is used in low cost  
applications for frequencies often in the HF and the bottom end of  
the VHF spectrum. Although it does not offer a particularly high  
level of performance, this RF connector is nevertheless satisfactory  
for many applications where cost may be an issue.
"The UHF RF connector was designed in the 1930s by E. Clark  
Quackenbush, a design engineer working for the Amphenol company. This  
RF connector design was aimed to cover frequencies in the range 0.6  
to 300 MHz and it was aimed at use within the radio industry. In view  
of the fact that the frequency of operation for the connector  
extended to 300MHz - the bottom of the UHF band of frequencies, it  
was given the name of UHF connector.

Connector designations
In view of the fact that the UHF connector was designed in the  
Amphenol company, it is also sometimes referred to as the Amphenol  
connector. In addition to this the plugs and sockets may be referred  
to by different designations. The plug may be referred to as a PL259  
coaxial connector, and the socket as an SO239 connector. These  
numbers arise from the original military numbers given to the UHF  
connectors

Basic description
These coaxial connectors have a threaded coupling, and this prevents  
them from being removed accidentally. It also enables them to be  
tightened sufficiently to enable a good low resistance connection to  
be made between the two halves.

The basic RF connector (PL259) is has a relatively large threaded  
hole through which the coax cable enters. This is suitable for large,  
low loss cable, and also make the connector suitable for relatively  
high power applications. However where smaller cable is to be used, a  
reducer sleeve that screws into the threaded coax cable entry hole  
may be used to make the cable entry diameter suite the size of the  
cable being used.

Limitations
The drawback of the UHF or Amphenol connector is that it has a non- 
constant impedance. This limits their use to frequencies of up to 300  
MHz, but despite this these UHF connectors provide a low cost RF  
connector suitable for many applications, provided that the  
frequencies do not rise. Also very low cost versions are available  
for applications such as CB operation, and these are not suitable for  
operation much above 30 MHz. In view of their non-constant impedance,  
these RF connectors, of any quality, are now rarely used for many  
professional applications, being generally limited to CB, amateur  
radio and some video and public address systems."


Bob, N7XY