142-1000-018 Emerson Network Power, 142-1000-018 Datasheet - Page 64

• Manufacturer Part Number: 142-1000-018
• Description: RF Connectors EPOXY STAKED FEEDTHROUGH
• Manufacturer: Emerson Network Power

Specifications of 142-1000-018

• Product: Connector
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

64
SMA - 50 Ohm Connectors
Field Replaceable - Application Notes
INCHES (MILLIMETERS) • CUSTOMER DRAWINGS AVAILABLE ON 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. These
types require special welding to install and can not be replaced without destroying the hermeticity of the circuit housing. True field
replaceable connectors, such as the Johnson line, 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 hermeticity 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
which involves adjusting the microstrip trace width to minimize any impedance discontinuities found in the transition area.
The plot shown below is representative of the typical return loss of a Johnson SMA field replaceable connector. To produce the data
shown below, a test fixture is created using the appropriate Johnson 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 fixture and the VSWR of
this test assembly is measured. The return loss data shown is equivalent to the square root of the measured VSWR of 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.
Although we do not publish a VSWR specification for field replaceable connectors, typical connector VSWR can be expected to be
better than 1.1 + .01f (f in GHz). A VSWR specification is not stated because an industry standard method for testing field replaceable
connectors does not exist. The actual performance of the connector is dependent upon the application for the following reasons:
As always, quotes for non-standard field replaceable connectors and/or hermetic seals are welcome.
1.
2.
3.
The choice of hermetic seal to be used by the customer is not specified by the connector manufacturer. Hermetic seals
produced by different manufacturers will not have the same electrical characteristics. For optimum electrical performance, we
recommend 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.
It is recommended that the hermetic seal be mounted flush with the circuit housing. Tolerance variations between the hermetic
seal and machined housing do not always guarantee an optimum transition to the connector. Some manufacturers recom-
mend an additional counterbore in the circuit housing to accommodate a solder washer during installation of the seal. We do
not recommend this type of installation because, if the counterbore is not completely filled with solder, electrical discontinuities
may be created.
As stated above, the transition between the hermetic seal pin and the microstrip trace will affect electrical performance.
Several different methods of hermetic seal mounting and seal pin to microstrip trace attachment are used in the industry. We
cannot recommend one method over the other as this is dependent upon the customer’s application.
Connectivity Solutions
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