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In this article of our This vs. That series, we compare the RG142 and RG400 cables. With this side by side analysis, we hope to make the differences between these cables more clear so that everyone is better informed when it comes to making a decision between two similar cables!

RG142 and RG400 are both high-temperature coax cables with a maximum temperature rating of 200°C, which allows for installation in heat-sensitive climates and projects. RG142 is a versatile coaxial cable designed for use in radio frequency, telecommunications, interconnects, and signal transfer applications. RG400 coax cable is well-suited for use in satellites, systems, and other tactical operations. RG142 and RG400 are similar in most regards, but there are a few subtle differences that set them apart. First, we'll take a look at each cable's construction.

RG142 vs RG400 Specs for Construction
RG142 RG400
Conductor Type Solid Stranded (19 strands)
Conductor Material Silver-coated Copper Clad Steel Silver Covered Copper
Dielectric Diameter .116” .116”
Shield Double Silver Plated Copper Braid Double Silver Plated Copper
Jacket FEP FEP
Overall Diameter .195” .195”
Weight 43 lbs/MFT 50 lbs/MFT

RG142 coax cable features a solid silver-coated copper-clad steel conductor, while RG400 coax cable has a stranded silver plated copper conductor. The differences in conductor material and type play a major role in the cable’s weight differences, the slight difference in pricing, and how they differ in terms of flexibility.

RG400 weighs 50 lbs/MFT which is slightly heavier than RG142, which weighs 43 lbs/MFT. RG400 coax is also more flexible and has a greater resistance to flexing fatigue failure than the RG142 coax. Finally, copper-clad steel is slightly less expensive than copper, so RG142 costs less than RG400.

RG142 vs RG400 Electrical Specs
RG142 RG400
Min. Temperature Rating -55°C -55°C
Max. Temperature Rating 200°C 200°C
Max. Voltage 1900 1900
Impedance (ohms) 50 +/-2 50 +/-2
Capacitance (pF/ft) 29.4 29.4
Max. Freq. (GHz) 12.4 11.0

In terms of electrical specs, RG142 and RG400 are able to withstand the same ratings across the board. Both cables are rated for up to 1900V with a temperature range of -55°C to 200°C.

RG142 Loss (Attenuation dB/100ft) RG400 Loss (Attenuation dB/100ft)
Typical Attenuation Max. Attenuation Typical Attenuation Max. Attenuation
100 MHz 3.8 4.4 4.1 4.5
400 MHz 8.1 9.3 8.6 10.5
1 GHz 13.7 15.3 14.2 18.1
2.4 GHz 23.3 25.0 23.6 30.2
5 GHz 37.4 41.8 37.0 52.1
10 GHz 60.0 70.7 57.8 78.0

Focusing on attenuation, it's important to keep in mind that the larger the conductor, the less the attenuation. The attenuation is directly aligned with frequency and determines how far the signal will travel over the coaxial cables. Because RG142 has a solid copper clad steel conductor, low-frequency electrical power is able to travel down the middle of the wire. The attenuation from the RG400 coax is slightly higher because of the conductor stranding.

If you are unsure about what coaxial cable you’ll need in order to meet the needs of your application, consult with a qualified engineer or with one of Allied’s knowledgeable sales reps. To learn more about RG142 and RG400, visit the coaxial cable main product page.