Description
Professional-Grade Flexible Double-Shielded Coaxial Cable
High-temperature 50-Ohm MIL-DTL-17/128 coaxial transmission line featuring double silver-plated copper braid shields, low-loss PTFE dielectric, and durable FEP jacket rated up to 12.4 GHz.
The Purchase Radios RG400 (MIL-Spec M17/128-RG400) is a commercial- and military-grade 50-Ohm coaxial transmission line engineered for demanding RF, microwave, aerospace, tactical operations, and repeater interconnection systems. Built to strict MIL-DTL-17 standards, this high-performance cable provides exceptional signal integrity, extreme thermal resilience from -55°C to +200°C (-67°F to +392°F), and minimal attenuation across frequencies reaching 12.4 GHz. Sold by the linear foot, it allows technicians to build custom jumper assemblies and antenna feedlines tailored to exact installation requirements under FCC Licensing standards.
Designed to maximize shielding isolation and mechanical durability, the Purchase Radios RG400 utilizes two overlapping tightly woven layers of silver-plated copper braid shielding, delivering greater than 95 dB of RF shielding effectiveness to eliminate EMI and signal bleed-through in densely packed repeater cabinets and test environments. The stranded 19-wire silver-plated copper inner conductor provides superior flexibility and fatigue resistance compared to solid-core cables like RG142, allowing a tight 1.0-inch repeated bend radius without deforming the solid extruded PTFE dielectric. Encased in a weather-, UV-, and chemical-resistant extruded tan Fluorinated Ethylene Propylene (FEP) Type IX jacket with a standard 0.195-inch outer diameter, RG400 withstands extreme temperatures, caustic fluids, direct burial, and severe mechanical vibration.
Key Features & Benefits
-
Double Silver-Plated Braid Shielding: Dual overlapping silver-coated copper braided shields deliver superior RF isolation, low insertion loss, and over 95 dB shielding effectiveness.
-
Extended Microwave Spectrum: Engineered to maintain low VSWR and stable 50-Ohm impedance across high-frequency RF applications up to 12.4 GHz.
-
Extreme Thermal Stability: Solid extruded PTFE dielectric and high-grade FEP jacket withstand continuous operating temperatures from -55°C to +200°C (-67°F to +392°F).
-
High Flexibility with 1-Inch Bend Radius: 19-strand silver-plated copper center core permits repeated 1.0-inch tight bends without conductor fracturing or impedance mismatch.
-
Sold by the Linear Foot: Order the exact continuous footage needed for custom jumper builds, repeater interconnects, or field repairs.
-
Chemical & Environmental Immunity: Non-flammable tan FEP jacket resists sunlight, moisture, caustic chemicals, hydraulic fluids, and outdoor abrasion.
Specifications
| Attribute |
Details |
| Brand |
Purchase Radios |
| Part Number / Military Spec |
RG400 (M17/128-RG400 / MIL-DTL-17/128) |
| Product Type |
Flexible Double-Shielded Coaxial RF Cable |
| Characteristic Impedance |
50 ± 2 Ohms |
| Maximum Operating Frequency |
12.4 GHz (12,400 MHz) |
| Operating Temperature Range |
-55°C to +200°C (-67°F to +392°F) |
| Velocity of Propagation |
69.5% – 70% |
| Capacitance |
29.4 pF/ft (96.5 pF/m) |
| Maximum Operating Voltage |
1,900 V RMS |
| Dielectric Withstanding Voltage |
3,000 V RMS |
| Corona Extinction Voltage |
1,900 V RMS |
| Conductor DC Resistance (20°C) |
0.91 Ohms per 100 ft (2.98 Ohms per 100 m) |
| Overall Cable Diameter |
0.195 in (4.95 mm) ± 0.005 |
| Minimum Bend Radius (Repeated) |
1.0 in (25.4 mm) |
| Nominal Weight |
50 lbs per 1,000 ft (0.050 lbs/ft) |
Cable Construction Specifications
| Cable Component |
Material & Plating Details |
Diameter (Inches) |
Diameter (Metric) |
| Inner Conductor |
Stranded Silver-Plated Copper (19 Strands of 0.008") |
0.0384 in ± 0.001 |
0.98 mm |
| Dielectric Core |
Solid Extruded Polytetrafluoroethylene (PTFE Type F-1) |
0.116 in |
2.95 mm |
| First Outer Shield |
Silver-Plated Copper Braid (94.8% Nominal Optical Coverage) |
0.136 in |
3.45 mm |
| Second Outer Shield |
Silver-Plated Copper Braid (93.6% Nominal Optical Coverage) |
0.156 in |
3.96 mm |
| Protective Outer Jacket |
Tan Fluorinated Ethylene Propylene (FEP Type IX per MIL-C-17) |
0.195 in ± 0.005 |
4.95 mm ± 0.13 |
Attenuation & Power Rating Chart
| Frequency (MHz) |
Frequency (GHz) |
Nominal Attenuation (dB/100 ft) |
Nominal Attenuation (dB/100 m) |
Max Average Power (Watts CW) |
| 100 MHz |
0.1 GHz |
4.1 dB |
13.5 dB |
1,200 W |
| 400 MHz |
0.4 GHz |
8.6 dB |
28.2 dB |
600 W |
| 1,000 MHz |
1.0 GHz |
14.2 dB |
46.6 dB |
350 W |
| 2,400 MHz |
2.4 GHz |
23.6 dB |
77.4 dB |
210 W |
| 5,000 MHz |
5.0 GHz |
37.0 dB |
121.4 dB |
130 W |
| 10,000 MHz |
10.0 GHz |
57.8 dB |
189.6 dB |
90 W |
| 12,400 MHz |
12.4 GHz |
65.0 dB |
213.2 dB |
75 W |
Compatibility
Compatible Tools, Connectors & Host Hardware
Recommended Accessories
Coaxial Cable Prep Tools & Wire
More Resources
Frequently Asked Questions
How do I order continuous lengths of Purchase Radios RG400 cable?
This cable is sold by the linear foot. Increase the quantity in your shopping cart to reflect the total footage required for your project, and your cable will be cut and delivered as a single continuous piece.
What connectors are compatible with RG400 coaxial cable?
Purchase Radios RG400 features a standard 0.195-inch outer diameter and is compatible with standard crimp or solder RF connectors designed for cable groups RG-400, RG-142, and RG-58 (including N-Type, BNC, SMA, TNC, and UHF PL-259 connectors).
What is the structural difference between RG400 and RG142?
Both cables share identical 0.195-inch diameters, double silver-plated copper shields, and high-temperature PTFE/FEP constructions. However, RG400 utilizes a stranded 19-wire inner conductor providing exceptional flexibility and repeated-bend endurance, whereas RG142 uses a solid copper center conductor suited for fixed, rigid runs.
Is this cable approved for direct burial and harsh outdoor exposure?
Yes. The extruded FEP jacket and solid PTFE dielectric core provide outstanding chemical resistance, UV protection, non-flammability, and zero degradation from moisture, making RG400 suitable for outdoor exposed runs and direct burial.
Does Purchase Radios RG400 meet military specifications?
Yes. This cable conforms to MIL-DTL-17/128 (M17/128-RG400) requirements, ensuring reliable electrical performance, consistent shielding, and precise physical dimensions.
Warranty
1-year manufacturer’s replacement warranty.
