50 Ohm SMA Field Replaceable 4-Hole Flange Mount Jack Receptacle - INCHES (MILLIMETERS) CUSTOMER DRAWINGS AVAILABLE UPON REQUEST Without EMI Gasket ACCEPTS FREQUENCY GOLD NICKEL PIN SIZE RANGE PLATED PLATED .036 (0.91) 142-1701-541 142-1701-546 0-26.5 GHz CCinincch Ch Coonnnnecectitivitvity Soy Solulutitioonsns 299 J299 Johnsohnson Aon Avveennue Sue SWW, W, Waassecaeca, MN 56093 U, MN 56093 USSA 800.247.8256 +1 507 833 8822 cA 800.247.8256 +1 507 833 8822 cincinchchconneconnectitivitvityy.c.com om SMA - 50 Ohm Connectors INCHES (MILLIMETERS) Field Replaceable - Application Notes CUSTOMER DRAWINGS AVAILABLE UPON REQUEST The field replaceable style of connector is known by many names in the industry, such as MIC launcher, hermetic seal launcher, spark plug launcher, etc. Some types, such as those known as spark plugs, have the hermetic seal incorporated into the connector. Thes e types require special welding to install and can not be replaced without destroying the hermeticity of the circuit housing. True field replaceable TM connectors, such as those manufactured by Johnson Components , are easy to install and replace. Because the hermetic seal is not incorporated into the connector design, the connector can be removed and replaced without destroying the hermetic seal or the h ermeticity of the circuit housing. All of the above mentioned connector types perform the same basic function - creating a transition from microstrip circuitry to a coaxial transmission line. Whenever possible, the hermetic seal pin diameter should be chosen as close as possible to the microstrip trace width. For optimum electrical performance, the transition from the hermetic seal to the microstrip trace must be properly compensated. Compen- sation involves adjusting the microstrip trace width to minimize any impedance discontinuities found in the transition area. TM The plot shown below is representative of the typical return loss of an Johnson Components field replaceable connector. To produce the TM data shown below, a test fixture is created using the appropriate Johnson Components hermetic seal. The fixture consists of a suitably thick spacer plate with the hermetic seal mounted flush to both surfaces. Two connectors are mounted back to back around the f ixture and the VSWR of this test assembly is measured. The return loss data shown is equivalent to the square root of the measured VSWR o f the test assembly. Since the connectors tested are of identical design, it can be stated with fair accuracy that the data shown represents the response of a single field replaceable connector and its transition to the hermetic seal. TM Although Johnson Components does not publish a VSWR specification for field replaceable connectors, typical connector VSWR can be expected to be less than 1.1 + .01f (f in GHz). A VSWR specification is not stated because an industry standard method for tes ting field replaceable connectors does not exist. The actual performance of the connector is dependent upon the application for the follo wing reasons: 1. The choice of hermetic seal to be used by the customer is not specified by the connector manufacturer. Hermetic seals produc ed by different manufacturers will not have the same electrical characteristics. For optimum electrical performance, Johnson Compo- TM nents recommends the use of our standard 142-1000-001, 002, 003 and 004 hermetic seals for pin diameters of .012 (0.30), .015 (0.38), .018 (0.46) and .020 (0.51). Custom hermetic seal configurations can be quoted. 2. It is recommended that the hermetic seal be mounted flush with the circuit housing. Tolerance variations between the hermeti c seal and machined housing do not always guarantee an optimum transition to the connector. Some manufacturers recommend an additional counterbore in the circuit housing to accommodate a solder washer during installation of the seal. Johnson Compo - TM nents does not recommend this type of installation because if the counterbore is not completely filled with solder, electrical discontinuities may be created. 3. The transition between the hermetic seal pin and the microstrip trace will affect electrical performance, as stated above. Several different methods of hermetic seal mounting and seal pin to microstrip trace attachment are used in the industry. Johnson TM Components can not recommend one method over the other as this is dependent upon the customers application. As always, quotes for non-standard field replaceable connectors and/or hermetic seals are welcome. CCinincch Ch Coonnnnecectitivitvity Soy Solulutitioonsns 299 J299 Johnsohnson Aon Avveennue Sue SWW, W, Waassecaeca, MN 56093 U, MN 56093 USSA 800.247.8256 +1 507 833 8822 cA 800.247.8256 +1 507 833 8822 cincinchchconneconnectitivitvityy.c.com om