What is RG400 Cable?

The RG400 is a high temperature coax cable used in a vast array of military and commercial applications. With a high temperature maximum of 200°C, in line with other coax cables like the RG142 Cable, this allows installation in heat sensitive environments.

Use in the military

The United States Military uses the M17/128-RG400, a military part number equivalent to the RG400 Cable. The testing of the RG400 and other military coax cables are very rigorous and the specifications even more so. The RG 400 manufacturers are required to test attenuation and structural return loss by sweeping 22 different 50-ohm cables over the frequency band for which their use is recommended. Among other tests for dimensional stability you can see why the RG400 cable is of high quality for tactical operations and aerospace technology

Electrical Specifications
Cable Construction
Loss & Power Handling

2 items

  • RG 400 C
    $0.00 / 1000 FT
    • Approx LBS/MFT: 50.00
    • Cond. Material: Silver-Coated Copper
    • Conductor Stranding: 19/.008
    Add to List
  • RG 400
    $0.00 / 1000 FT
    • Approx LBS/MFT: 50.00
    • Cond. Material: Silver-Coated Copper
    • Conductor Stranding: 19/.008
    Add to List

RG-400 Specs

RG 400 Coax Cable Electrical Specifications

  • Impedance: 50 +/-2 (ohms)
  • Capacitance: 29.4 (pF/ft)
  • Maximum Voltage: 1900 (vms)
  • Maximum Frequency: 12.4 GHz
  • Minimum Temperature: -55°C
  • Maximum Temperature : 200°C
  • Mil-Spec Equivalent : M17/128-RG400 Cable
  • Bend Radius : 1.0"
  • Weight : 50 lbs/mft

RG 400 Cable Construction

  • Conductor (Inner Conductor): Silver Covered Copper 
  • Dielectric: Solid Polytetrafluoroethylene (PTFE)
  • Shield (Outer Conductor): Double Silver Covered Copper Shields
  • Jacket: Flourinated Ethylene Propylene (FEP) Type IX per MIL-C-17

RG 400 Diameter

  • Center Conductor: 0.0384" (19/.008")
  • Dielectric Diameter: 0.116"
  • Shield Diameter: 0.156"
  • Overall Diameter: 0.195"

RG 400 Loss (Attenuation) & Power Handling

Freq. (MHz) Typical Max
100 4.1 4.5 dB/100ft.
400 8.6 10.5 dB/100ft.
1000 14.2 18.1 dB/100ft.
2400 23.6 30.2 dB/100ft.
5000 37.0 52.1 dB/100ft.
10000 57.8 78.0 dB/100ft.


RG 400 Datasheet

If you're in sales, customer service, or need to show a client, we offer the ability to download a printable spec sheet of the RG400 coaxial cable. Download the RG400 Datasheet PDF.

RG 400 Video

RG 400 Applications:

The RG400 cable is extensively and reliably used in the following types of projects:

  • Radio frequency
  • Telecommunications Applications
  • Radio Systems
  • Test Cables
  • Signal Transfer Applications
  • Interconnects

RG 400 Cable is also approved for direct burial.  Whether it's being used in an in-flight entertainment system or a telecommunications application it is a very versatile coax cable to use commercially and militarily.

Per specification, RG400 coax cable will have splices. If continuous lengths are needed, please alert your Allied Wire & Cable Representative.