SMA - 50 Ohm Connectors
Field Replaceable - Application Notes
INCHES (MILLIMETERS)
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 fie ld replaceable
connectors, such as those manufactured by Johnson Components
TM
, 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 t race 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.
The plot shown below is representative of the typical return loss of an Johnson Components
TM
field replaceable connector. To produce the
data shown below, a test fixture is created using the appropriate Johnson Components
TM
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 re presents the
response of a single field replaceable connector and its transition to the hermetic seal.
Although Johnson Components
TM
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 Comp o-
nents
TM
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.
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 -
nents
TM
does not recommend this type of installation because if the counterbore is not completely filled with solder, electrical
discontinuities may be created.
The transition between the hermetic seal pin and the microstrip trace will affect electrical performance, as stated above. S everal
different methods of hermetic seal mounting and seal pin to microstrip trace attachment are used in the industry. Johnson
Components
TM
can not recommend one method over the other as this is dependent upon the customer’s application.
2.
3.
As always, quotes for non-standard field replaceable connectors and/or hermetic seals are welcome.
Cinch Connectivity Solutions
299 Johnson Avenue SW, Waseca, MN 56093 USA • 800.247.8256 • +1 507 833 8822 • cinchconnectivity.com
SMA - 50 Ohm Connectors
Specifications
INCHES (MILLIMETERS)
CUSTOMER DRAWINGS AVAILABLE UPON REQUEST
ELECTRICAL RATINGS
Impedance:
50 ohms
Frequency Range:
Dummy loads .......................................................................... 0-2 GHz
Flexible cable connectors ................................................... 0-12.4 GHz
Uncabled receptacles, RA semi-rigid and adapters ........... 0-18.0 GHz
Straight semi-rigid cable connectors and
field replaceable connectors ............................................... 0-26.5 GHz
VSWR:
(f = GHz)
Straight
Right Angle
Cabled Connectors Cabled Connectors
RG-178 cable .............................. 1.20 + .025f
1.20 + .03f
RG-316, LMR-100 cable .............. 1.15 + .02f
1.15 + .03f
RG-58, LMR-195 cable ................ 1.15 + .01f
1.15 + .02f
RG-142 cable ............................... 1.15 + .01f
1.15 + .02f
LMR-200, LMR-240 cable ............ 1.10 + .03f
1.10 + .06f
.086 semi-rigid ............................ 1.07 + .008f
1.18 + .015f
.141 semi-rigid (w/contact) .......... 1.05 + .008f
1.15 + .015f
.141 semi-rigid (w/o contact) ...... 1.035 + .005f
Jack-bulkhead jack adapter and plug-plug adapter ................. 1.05 + .01f
Jack-jack adapter and plug-jack adapter ............................... 1.05 + .005f
Uncabled receptacles, dummy loads .................................................. N/A
Field replaceable (see
page 59) .........................................................
N/A
Working Voltage:
(Vrms maximum)
Connectors for Cable Type
Sea Level 70K Feet
RG-178 ...................................................................... 170
45
RG-316; LMR-100, 195, 200 ..................................... 250
65
RG-58, RG-142, LMR-240, .086 semi-rigid,
uncabled receptacles, .141 semi-rigid w/o contact ... 335
85
.141 semi-rigid with contact and adapters ................. 500
125
Dummy loads ................................................................................. N/A
Dielectric Withstanding Voltage:
(VRMS minimum at sea level)
Connectors for RG-178 ................................................................... 500
Connectors for RG-316; LMR-100, 195, 200 .................................. 750
Connectors for RG-58, RG-142, LMR-240, .086 semi-rigid,
field replaceable, uncabled receptacles ...................................... 1000
Connectors for .141 semi-rigid with contact and adapters ............ 1500
Connectors for .141 semi-rigid w/o contact, dummy loads .............. N/A
Corona Level:
(Volts minimum at 70,000 feet)
Connectors for RG-178 ................................................................... 125
Connectors for RG-316; LMR-100, 195, 200 .................................. 190
Connectors for RG-58, RG-142, LMR-240, 086 semi-rigid,
uncabled receptacles, .141 semi-rigid w/o contact .......................... 250
Connectors for .141 semi-rigid with contact and adapters .............. 375
Dummy loads ...................................................................................... N/A
Insertion Loss:
(dB maximum)
Straight flexible cable connectors
and adapters ...................... 0.06 f (GHz), tested at 6 GHz
Right angle flexible cable
connectors ......................... 0.15 f (GHz), tested at 6 GHz
Straight semi-rigid cable
connectors with contact ..... 0.03 f (GHz), tested at 10 GHz
Right angle semi-rigid cable
connectors ......................... 0.05 f (GHz), tested at 10 GHz
Straight semi-rigid cable
connectors w/o contact ...... 0.03 f (GHz), tested at 16 GHz
Straight low loss flexible
cable connectors ................ 0.06 f (GHz), tested at 1 GHz
Right Angle low loss flexible
cable connectors ................ 0.15 f (GHz), tested at 1 GHz
Uncabled receptacles, field replaceable, dummy loads ..................... N/A
Insulation Resistance:
5000 megohms minimum
Contact Resistance:
(milliohms maximum)
Initial After Environmental
Center contact (straight cabled connectors
and uncabled receptacles) ........................... 3.0*
4.0*
Center contact (right angle cabled
connectors and adapters) .............................. 4.0
6.0
Field replaceable connectors ........................ 6.0
8.0
Outer contact (all connectors) ........................... 2.0
N/A
Braid to body (gold plated connectors) ............. 0.5
N/A
Braid to body (nickel plated connectors) ........... 5.0
N/A
*N/A where the cable center conductor is used as a contact
RF Leakage:
(dB minimum, tested at 2.5 GHz)
Flexible cable connectors, adapters and .141 semi-rigid
connectors w/o contact ............................................................. -60 dB
Field replaceable w/o EMI gasket .............................................. -70 dB
.086 semi-rigid connectors and .141 semi-rigid connectors
with contact, and field replaceable with EMI Gasket ................ -90 dB
Two-way adapters ...................................................................... -90 dB
Uncabled receptacles, dummy loads .............................................. N/A
RF High Potential Withstanding Voltage:
(Vrms minimum, tested at 4
and 7 MHz)
Connectors for RG-178 ................................................................... 335
Connectors for RG-316; LMR-100, 195, 200 .................................. 500
Connectors for RG-58, RG-142, LMR-240, .086 semi-rigid,
.141 semi-rigid cable w/o contact, uncabled receptacles .............. 670
Connectors for .141 semi-rigid with contact and adapters ............ 1000
Power Rating (Dummy Load):
0.5 watt @ + 25°C, derated to 0.25 watt @
+125°C
MECHANICAL RATINGS
Engagement Design:
MIL-C-39012, Series SMA
Engagement/Disengagement Force:
2 inch-pounds maximum
Mating Torque:
7 to 10 inch-pounds
Bulkhead Mounting Nut Torque:
15 inch-pounds
Coupling Proof Torque:
15 inch-pounds minimum
Coupling Nut Retention:
60 pounds minimum
Contact Retention:
6 lbs. minimum axial force (captivated contacts)
4 inch-ounce minimum torque (uncabled receptacles)
Cable Retention:
Axial Force*(lbs) Torque (in-oz)
Connectors for RG-178 ............................ 10
N/A
Connectors for RG-316, LMR-100 ........... 20
N/A
Connectors for LMR-195, 200 .................. 30
N/A
Connectors for RG-58, LMR-240 ............. 40
N/A
Connectors for RG-142 ............................ 45
N/A
Connectors for .086 semi-rigid ................. 30
16
Connectors for .141 semi-rigid ................. 60
55
*Or cable breaking strength whichever is less.
Durability:
500 cycles minimum
100 cycles minimum for .141 semi-rigid connectors w/o contact
(Meets or exceed the applicable paragraph of MIL-C-39012)
Temperature Range:
- 65°C to + 165°C
Thermal Shock:
MIL-STD-202, Method 107, Condition B
Corrosion:
MIL-STD-202, Method 101, Condition B
ENVIRONMENTAL RATINGS
Shock:
MIL-STD-202, Method 213, Condition I
Vibration:
MIL-STD-202, Method 204, Condition D
Moisture Resistance:
MIL-STD-202, Method 106
†Avoid user injury due to misapplication. See safety advisory definitions inside front cover.
Cinch Connectivity Solutions
299 Johnson Avenue SW, Waseca, MN 56093 USA • 800.247.8256 • +1 507 833 8822 • cinchconnectivity.com
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