The Good, the Bad and the Ugly RF Connectors The Good, the Bad and the Ugly

Coaxial cable as we know it was patented by AT&T in 1931 Coaxial cable was first conceived in the 1880’s and used in transoceanic cables at that time Coaxial cable as we know it was patented by AT&T in 1931 Designed for wide bandwidth baseband television camera signals Came into wide use during and after WWII.

Designed in 1930’s by E. Clark Quackenbush – worked for Amphenol PL-259 – “Plug” #259 – military nomenclature Designed in 1930’s by E. Clark Quackenbush – worked for Amphenol Intended for use from 0.6 MHz to 300 MHz Not a “constant impedance” connector Impedance of a mated PL-259/SO-238 pair is 33 to 36 ohms, depending on manufacturer

PL-259 / SO-239

The length of the impedance mismatch in a SO-239 is 0.77” The length of the impedance mismatch in a PL-259 is 0.25” The length of the impedance mismatch in a SO-239 is 0.77” Thus, a mated PL-259 / SO-239 has an impedance mismatch length of 1.03” At 75 meters, this length is insignificant At 2 meters, represents 1/80th of a wavelength and mismatch is measurable At 70 cm, represents 1/25th of a wavelength and mismatch is significant

Type N

Type N

BNC (Bayonet Neill–Concelman) and SMA (Subminiature Version A) Connectors

Direct connection of test cables using superb SMAs. Item Description Baseline: Direct connection of test cables using superb SMAs. SMA: Same as baseline plus two more SMA barrels. BNC: Two SMA to BNC Converters plus one BNC Barrel in between. TNC: Two SMA to TNC Converters plus one TNC Barrel in between. N: Two SMA to N Converters plus one N Barrel in between. UHF 1″ Cl: This is a 1″ Amphenol Model PL-258 Barrel with clear dieletric. UHF 1″ Wt: El cheapo 1″ SO-239 Barrel with White dielectric. UHF 2″ Cl: A 2″ SO-239 Barrel with Clear dielectric. UHF 3″ Cl: The combination of the Amphenol 1″ and the 2″ using a Male-Male joiner. It is really about 3.5″ long. UHF T Wt: A UHF T adapter with two SO-239 and one PL259 and White dieletric. The PL259 port was left open. UHF Ft Cl: A 12.5″ long SO-239 Barrel. This is the thing used to stick through walls. PL/SO: One SMA to N, then N to SO-239 Converter directly mated to one PL259 to TNC converter then TNC is adapted to SMA. This is the onlynon-barrel UHF configuration and presents the smallest and shortest impedance bump to the RF signal of all the UHF connections under test.