BNC Connector Plug 31-321-RFX Equivalent & Substitute Parts

Part Overview

The Amphenol RF 31-321-RFX is a BNC connector plug designed for 50-ohm coaxial cable applications. This male pin connector features crimp termination for both center contact and shield, with a bayonet lock fastening mechanism. The part is classified as Active product status with 1004 units in current inventory.

Equivalent and substitute parts are necessary when the primary part number becomes unavailable, when design revisions require alternative materials or specifications, or when procurement from multiple qualified sources is required for supply chain resilience.

Key Parameters

Parameter	Value
Connector Style	BNC
Connector Type	Plug, Male Pin
Impedance	50 Ohms
Contact Termination	Crimp
Shield Termination	Crimp
Mounting Type	Free Hanging (In-Line)
Fastening Type	Bayonet Lock
Frequency - Max	4 GHz
Voltage Rating	500 V
Operating Temperature	-65°C ~ 165°C
Insertion Loss	0.2 dB
Mating Cycles	500

Substitute Part Grouping Explanation

Substitution eligibility for the 31-321-RFX is determined by the following critical parameters:

Primary Substitution Criteria:

Connector Style: BNC (mandatory)
Connector Type: Plug, Male Pin (mandatory)
Impedance: 50 Ohms (mandatory)
Contact Termination: Crimp (mandatory)
Shield Termination: Crimp (mandatory)
Mounting Type: Free Hanging (In-Line) (mandatory)
Fastening Type: Bayonet Lock (mandatory)
Frequency - Max: 4 GHz (mandatory)
Voltage Rating: 500 V (mandatory)

Secondary Compatibility Parameters:

Cable Group compatibility (RG-59, 59B, 62, 140, 210, Belden 8241, 8263, 8279, 9209)
Center Contact Material: Brass
Body Material: Zinc Die Cast or Brass
Body Finish: Nickel
Center Contact Plating: Gold or Silver
Dielectric Material: POM Acetal or PTFE
Operating Temperature range: -65°C ~ 165°C or -55°C ~ 85°C
Mating Cycles: 500

Parts meeting all primary criteria are classified as direct equivalents. Parts meeting primary criteria with variations in secondary parameters are classified as parametric equivalents. Parts with different cable group compatibility or material specifications are classified as similar alternatives.

Parameter Comparison

Part Number	Manufacturer	Product Status	Body Material	Dielectric Material	Center Contact Plating	Operating Temp	Cable Group	Inventory	RoHS Status
31-321-RFX	Amphenol RF	Active	Zinc Die Cast	POM Acetal	Gold	-65°C ~ 165°C	RG-59, 59B, 62, 140, 210, Belden 8241, 8263, 8279, 9209	1004 Pcs	ROHS3 Compliant
31-321	Amphenol RF	Active	Brass	PTFE	Gold	-65°C ~ 165°C	RG-59, 59B, 62, 140, 210, Belden 8241, 8263, 8279, 9209	710 Pcs	ROHS3 Compliant
031-321-10RFX	Amphenol RF	Not For New Designs	Brass	POM Acetal	Gold	-65°C ~ 165°C	RG-59, 59B, 62, 140, 210, Belden 8241, 8263, 8279, 9209	1101 Pcs	ROHS3 Compliant
31-4702	Amphenol RF	Active	Brass	PTFE	Silver	-65°C ~ 165°C	RG-59, 59B, 62, 140, 210, Belden 8241, 8263, 8279, 9209	959 Pcs	RoHS non-compliant
1-5221128-1	TE Connectivity AMP Connectors	Obsolete	Brass	Polyethylene (PE)	Gold	-55°C ~ 85°C	RG-59, 59A, 59B, 62, 62A, 62B	922 Pcs	RoHS Compliant
227079-7	TE Connectivity AMP Connectors	Active	Brass	Polyethylene (PE)	Gold	-55°C ~ 85°C	RG-59, 59A, 59B, 62, 62A, 62B	910 Pcs	RoHS non-compliant
5285	Pomona Electronics	Active	Brass	PTFE	Gold	Not specified	RG-58, 58A, 58C, 141, 141A	647 Pcs	ROHS3 Compliant

Engineering Selection Recommendations

Primary Selection (Direct Equivalent): The part number 31-321 (Amphenol RF) is the recommended primary equivalent. Both parts share identical electrical specifications, impedance, frequency rating, and voltage rating. The 31-321 maintains Active product status and ROHS3 compliance. Material differences (Brass body vs. Zinc Die Cast, PTFE vs. POM Acetal dielectric) do not affect functional compatibility within the specified operating parameters.

Secondary Selection (Parametric Equivalent): The part number 031-321-10RFX (Amphenol RF) meets all primary electrical and mechanical criteria. However, this part carries "Not For New Designs" product status, limiting its use to legacy system support or existing inventory management. ROHS3 compliance is maintained.

Tertiary Selection (Active Alternative): The part number 31-4702 (Amphenol RF) is functionally equivalent with Active product status. The primary distinction is silver center contact plating versus gold plating on the main part. RoHS non-compliance status restricts use in applications requiring RoHS certification.

Cross-Manufacturer Alternatives: TE Connectivity AMP Connectors part 227079-7 is Active and functionally equivalent for applications with reduced operating temperature range (-55°C ~ 85°C versus -65°C ~ 165°C). RoHS non-compliance applies. Cable group compatibility differs (RG-59, 59A, 59B, 62, 62A, 62B).

TE Connectivity AMP Connectors part 1-5221128-1 is Obsolete and not recommended for new procurement.

Alternative Manufacturer: Pomona Electronics part 5285 is Active and ROHS3 compliant. Cable group compatibility is limited to RG-58, 58A, 58C, 141, 141A. Operating temperature specification is not provided. This part is suitable only for applications using the specified cable groups.

Frequently Asked Questions (FAQ)

Q: Can I substitute 31-321 for 31-321-RFX in my application?

A: Yes. Both parts are BNC 50-ohm male plug connectors with crimp termination, bayonet lock fastening, and identical electrical ratings. Material composition differs (body material and dielectric), but this does not affect electrical performance within the specified operating parameters. The 31-321 is Active and ROHS3 compliant.

Q: What is the difference between 31-321-RFX and 031-321-10RFX?

A: Both parts meet identical electrical specifications and cable compatibility. The 031-321-10RFX carries "Not For New Designs" status, indicating it is reserved for legacy applications. The 31-321-RFX is the current active part number. For new designs, 31-321-RFX is the preferred selection.

Q: Can I use 227079-7 (TE Connectivity) instead of 31-321-RFX?

A: Functional substitution is possible for applications operating within -55°C to 85°C temperature range. The 31-321-RFX supports -65°C to 165°C. Cable group compatibility differs: 227079-7 supports RG-59, 59A, 59B, 62, 62A, 62B, while 31-321-RFX supports RG-59, 59B, 62, 140, 210, Belden 8241, 8263, 8279, 9209. RoHS non-compliance applies to 227079-7.

Q: Is 31-4702 RoHS compliant?

A: No. Part 31-4702 is RoHS non-compliant. If RoHS compliance is required, use 31-321, 31-321-RFX, or 5285 instead.

Q: What cable types are compatible with 31-321-RFX?

A: RG-59, 59B, 62, 140, 210, Belden 8241, 8263, 8279, and 9209. The Pomona Electronics 5285 supports different cable groups (RG-58, 58A, 58C, 141, 141A) and is not interchangeable for applications requiring the primary cable group.

Q: Can I use Pomona Electronics 5285 as a substitute?

A: Only if your application uses RG-58, 58A, 58C, 141, or 141A cable types. The 5285 is not compatible with the cable groups specified for 31-321-RFX. The 5285 is Active and ROHS3 compliant.

Q: What is the operating temperature range for 31-321-RFX?

A: -65°C to 165°C. TE Connectivity alternatives (227079-7 and 1-5221128-1) operate within -55°C to 85°C, a narrower range. Verify application temperature requirements before substitution.

Q: Is 1-5221128-1 still available?

A: No. This part is classified as Obsolete and is not recommended for new procurement. Use 227079-7 (TE Connectivity) or Amphenol RF alternatives instead.

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