RG 111 refers to a family of coaxial cable assemblies often specified in military, aerospace, and instrumentation applications where controlled impedance, ruggedness, and stable signal transfer are required. This overview explains what RG 111 designates, how it is constructed, the performance characteristics it typically provides, and the contexts in which it remains relevant. The intent is to give engineers, technical buyers, and decision-makers an enduring, reference-quality explanation that prioritizes specifications, use cases, and practical considerations over marketing claims.
What RG 111 Designates: Type, Impedance, and Jacket
In formal specs, RG 111 is a type designation for a coaxial cable with 75 ohm characteristic impedance, commonly built with solid or semi-rigid construction and polyethylene or similar dielectric. Historically, RG 111 was MIL-C-17-style cable used in test equipment, measurement systems, and avionics. The outer jacket is typically tough and resistant to abrasion, oils, and some chemicals. While product names and materials can vary by vendor, RG 111 commonly appears in 50, 75, or 93 ohm flavors, with 75 ohm being standard for video and test applications. Impedance tolerances, connector types, and shielding levels are set by the relevant military specs or industry equivalents that the cable is certified to meet.
Common Specifications and Performance Attributes
Below is a concise comparison of typical RG 111 style attributes when encountered in procurement or technical documentation. Values are representative ranges drawn from legacy military and commercial references; exact figures depend on the manufacturer and test method. Always confirm specifications against the current datasheet and applicable test reports.
| Attribute | Verified Detail or Typical Range | Source Type |
|---|---|---|
| Characteristic Impedance | 75 ohm (common); also 50 and 93 ohm variants | Military/Commercial Spec Sheets |
| Dielectric Material | Foamed polyethylene or solid polyethylene | Cable Data Sheets |
| Shielding | Double or triple braid; coverage >90% | Vendor Test Reports |
| Frequency Range | DC to 1 GHz typical; up to 3 GHz in some designs | Manufacturer Datasheets |
| Max Rated Voltage | 150 to 300 V RMS typical | MIL-C-17 / UL Data |
| Temperature Range | -65°C to +125°C operational | Certification Documents |
| Connector Styles | N, BNC, TNC, Type C/U connectors common | Connector Catalogs |
Applications and Use Cases
RG 111 style cables are selected when the system requires stable 75 ohm performance for RF and video, plus mechanical durability in demanding environments. Typical use cases include test and measurement setups, laboratory instrumentation, surveillance camera links, broadcast equipment installations, and certain military avionics and communications racks. The semi-rigid or rigid forms are useful in fixed installations where precise routing and long-term impedance stability matter more than frequent reconfiguration. Flexible braided versions are chosen when the cable must endure movement or repeated bending while preserving shielding effectiveness.
Installation and Handling Best Practices
Proper handling of RG 111 begins with inspecting the cable for damage before deployment and avoiding excessive bending near connectors. Follow bend radius rules from the manufacturer; tight bends can deform the dielectric and degrade impedance and return loss. When terminating, maintain consistent dielectric support and shield integrity; poor termination is a common cause of mismatch and increased VSWR. For long runs, account for attenuation at the system frequency and plan amplifier or re-driver stages as needed. Shielded conduit or grounded raceways help reduce external interference when the cable runs near noise sources.
Standards, Compliance, and Specification References
RG 111 cables are often associated with military specifications such as MIL-C-17, and many commercial equivalents reference those standards for construction, testing, and performance. Key attributes to verify include shielding coverage, dielectric type, voltage rating, and temperature range. Compliance marks and test reports should cite relevant standards like MIL-STD-130 for marking or IPC-601 for aerospace printed board laminates when applicable. Buyers should confirm that the supplier’s data sheet references the current revision of the governing specification and that test methods align with recognized industry practices.
When to Choose RG 111 and Alternatives to Consider
Choose RG 111 when you need a robust 75 ohm coaxial cable for stable RF or video transmission in environments where standard consumer cables lack the required shielding, voltage rating, or temperature performance. If flexibility is the priority and the frequency is moderate, standard RG-6 or low-loss variants may be more cost-effective. For very high frequency or ultra-low loss requirements, foamed-dielectric low-loss cables outperform RG 111 at higher frequencies. When space or motion constraints are severe, semi-rigid or flexible indoor cables designed for test benches may be better suited. Always compare attenuation, shielding, connector compatibility, and total cost of ownership before deciding.
Summary and Key Takeaways
- RG 111 denotes a 75 ohm coaxial cable family used in test, video, and demanding environments.
- Typical performance includes DC to around 1 GHz, good shielding, and robust jackets for harsh conditions.
- Verify exact specs against current datasheets; real values vary by vendor and cable formulation.
- Use RG 111 when system requirements call for durable, stable 75 ohm cables in professional or mil/aero contexts.
- Compare alternatives such as RG-6, low-loss coax, or semi-rigid cables to match flexibility, frequency, and budget needs.
For long-term reliability, document the exact part number, specification revision, and test reports in your engineering records. When in doubt, request samples and verify electrical performance in your own environment under real installation conditions. This approach ensures that RG 111 continues to meet your project’s requirements for signal integrity, durability, and compliance over the life of the system.