UG-491/U(40) BNC Coaxial Connector Adapter - Equivalent & Substitute Parts

Part Overview

The UG-491/U(40) is a BNC coaxial connector adapter manufactured by Hirose Electric Co Ltd, designed for plug-to-plug connections in 50-ohm RF applications. This adapter features male pin centers on both ends with straight orientation and bayonet locking fasteners. The part is classified as obsolete, making identification of active equivalent components essential for ongoing system maintenance and new procurement requirements.

Substiute Parts

UG-491/U(40)

Hirose Electric Co LtdIn Stock: 1134UG-491/U(40) Datasheet

Current PartRFQ

31-218

Amphenol RFIn Stock: 126031-218 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the UG-491/U(40) is determined by strict equivalence across the following critical parameters:

• Adapter configuration: Plug-to-plug topology with identical connector series (BNC to BNC)
• Center pin gender: Male-to-male configuration on both mating ends
• Electrical impedance: 50-ohm characteristic impedance
• Mechanical interface: Bayonet lock fastening system
• Frequency performance: Maximum operating frequency of 4 GHz or higher
• Dielectric composition: PTFE material for signal integrity
• Physical form factor: Straight, free-hanging in-line mounting

The substitute part 31-218 (Amphenol RF) meets all these criteria and is classified as active product status, providing a direct functional replacement for the obsolete UG-491/U(40).

Parameter Comparison

Engineering Selection Recommendations

The 31-218 (Amphenol RF) serves as the direct active equivalent for the obsolete UG-491/U(40). Both parts maintain identical electrical and mechanical specifications across all critical parameters: BNC plug-to-plug configuration, 50-ohm impedance, 4 GHz maximum frequency, and bayonet fastening.

The primary distinction is product status: the UG-491/U(40) is obsolete, while the 31-218 is active and currently in production. The 31-218 also carries ROHS3 compliance, representing current regulatory alignment. The body finish differs (silver versus nickel), which does not affect electrical performance or mechanical compatibility in standard RF applications.

For new designs or system replacements, the 31-218 is the appropriate selection. For legacy system maintenance where original specifications must be preserved, the UG-491/U(40) remains functionally equivalent if inventory is available.

Frequently Asked Questions (FAQ)

Q: Can the 31-218 directly replace the UG-491/U(40) in existing installations?

A: Yes. Both adapters share identical connector series (BNC to BNC), center pin gender (male to male), impedance (50 ohms), fastening mechanism (bayonet lock), and frequency rating (4 GHz). The mechanical and electrical interfaces are fully compatible.

Q: Does the difference in body finish (silver vs. nickel) affect performance?

A: No. Body finish does not impact electrical performance or mechanical mating in RF coaxial adapter applications. Both finishes provide adequate corrosion resistance and conductivity for standard operating conditions.

Q: Why is the UG-491/U(40) classified as obsolete?

A: Obsolete status indicates the part is no longer manufactured by Hirose Electric Co Ltd. The 31-218 from Amphenol RF provides functional equivalence and active availability for ongoing procurement.

Q: Are there packaging differences between these parts?

A: The UG-491/U(40) packaging is not specified in available data. The 31-218 is supplied in bulk packaging. Confirm packaging requirements with your procurement specifications.

Q: Do both parts meet current regulatory requirements?

A: The UG-491/U(40) is RoHS Compliant. The 31-218 is ROHS3 Compliant, representing alignment with current regulatory standards. Both parts carry MSL 1 (Unlimited) moisture sensitivity classification.

Q: What is the mating cycle rating for these adapters?

A: The UG-491/U(40) specifies 5000 mating cycles. The 31-218 mating cycle rating is not provided in available technical data. Consult the manufacturer for cycle life specifications if this parameter is critical to your application.