About the EIA 7/8 Interface

EIA flange connectors are commonly used to connect two components in a high power coaxial transmission line. EIA stands for “Electronic Industries Alliance” which is a standards body that defines the interface configuration. Typically these are only required in very high power transmitting installations (10s of kW to MW) where the feedline diameters may be several inches. One side of the connection is denoted as a male connection, or bullet, while the other side is denoted as the female connection, or cup. The mounting flange design, inner and outer conductor dimensions are standardized by the EIA. They are commonly referred to by the outer diameter of the outer conductor in fractional inches. Sizes covered under these two standards range from 3/8 to 6 1/8 inch outside diameter (OD) for 50 ohm designs. Common flange sizes include 1-5/8 (3 GHz max frequency) and 7/8 (6 GHz max frequency). EIA flange designs are commonly used in military applications connecting high power antennas for ground or airborne radar as well as commercial applications in industrial equipment, broadcast and telecom infrastructure.


Diagram

EIA 7/8technical diagram

click to enlarge

Specifications

Electrical

Nominal Impedence50 ohms ohms
Frequency RangeDC to 6 GHz
Voltage Rating2800 volts rms
Dielectric Withstanding
Voltage
5800 volts rms

Mechanical

Mating Characteristicsper EIA STD RS-225 and MIL-DTL-24044
Connector Durability500 cycles min.
Recommended TorqueN/A (Flange Mounting)

Materials/Finishes

BodyBrass, Silver or Nickel Plated
Contacts (Inner)Male: Beryllium Copper, Silver or Gold Plated. Female: Brass, Silver or Gold Plated
Contacts (Outer)Brass, Silver or Nickel Plated
Contacts (Slotted)Beryllium Copper, Silver or Nickel Plated
InsulatedTeflon
Gaskets & SealsSilicone Rubber

Environmental

Tempurature Range-85°F to +329°F (-65°C to +165°C)
VibrationMIL-STD-202 Method 204
ShockMIL-STD-202 Method 213
Moisture ResistanceMIL-STD-202 Method 106
Corrosion (salt spray)MIL-STD-202 Method 101

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EIA 7/8 Performance Charts