Pomona Electronics 72987 SMB Connector Plug - Equivalent & Substitute Parts

Part Overview

The Pomona Electronics 72987 is an SMB connector plug with female socket configuration, designed for 50-ohm RF applications. This connector features right-angle, free-hanging (in-line) mounting with push-on contact termination and crimp shield termination. The part is classified as obsolete, making equivalent substitute parts necessary for ongoing system maintenance and new designs requiring compatible RF connectivity solutions.

Key Parameters

Parameter	Value
Manufacturer Part Number	72987
Manufacturer	Pomona Electronics
Connector Style	SMB
Connector Type	Plug, Female Socket
Impedance	50 Ohms
Mounting Type	Free Hanging (In-Line), Right Angle
Contact Termination	Push On
Shield Termination	Crimp
Frequency - Max	3 GHz
Operating Temperature Range	-65°C ~ 165°C
Voltage Rating	250 V
Mating Cycles	500
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the Pomona Electronics 72987 are identified based on the following critical parameters that determine functional compatibility:

Core Compatibility Criteria:

Connector style: SMB (maintained across all substitutes)
Connector type: Plug, female socket (maintained)
Impedance: 50 ohms (maintained)
Mounting type: Free hanging (in-line), right angle (maintained)
Shield termination: Crimp (maintained)
Fastening type: Snap-on (maintained)
Number of ports: 1 (maintained)
Dielectric material: PTFE (maintained)

Substitution Allowances: Contact termination differs from the original push-on design. Substitute parts utilize solder termination, which is an acceptable alternative for SMB connector applications where cable attachment methodology can be adapted to the assembly process. Both substitute parts are manufactured by Amphenol RF and maintain active product status, ensuring ongoing availability and support.

Cable group compatibility varies between substitutes. The original part supports RG-178 and RG-196 cables. Substitute 903-NM291P-51A maintains RG-178 series compatibility (RG-178, 178A, 178B, 196, 196A, M17/93-RG178), while substitute 903-NM289P-51A supports a broader cable range including RG-174 and LMR-100 series.

Parameter Comparison

Parameter	Pomona 72987	Amphenol 903-NM291P-51A	Amphenol 903-NM289P-51A
Connector Style	SMB	SMB	SMB
Connector Type	Plug, Female Socket	Plug, Female Socket	Plug, Female Socket
Impedance	50 Ohms	50 Ohms	50 Ohms
Mounting Type	Free Hanging (In-Line), Right Angle	Free Hanging (In-Line), Right Angle	Free Hanging (In-Line), Right Angle
Contact Termination	Push On	Solder	Solder
Shield Termination	Crimp	Crimp	Crimp
Fastening Type	Snap-On	Snap-On	Snap-On
Frequency - Max	3 GHz	4 GHz	4 GHz
Operating Temperature Range	-65°C ~ 165°C	-40°C ~ 155°C	-40°C ~ 155°C
Voltage Rating	250 V	Not specified	Not specified
Mating Cycles	500	500	500
Dielectric Material	PTFE	PTFE	PTFE
Center Contact Plating	Gold	Gold	Gold
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active

Engineering Selection Recommendations

Both Amphenol RF substitutes (903-NM291P-51A and 903-NM289P-51A) are active products with ROHS3 compliance, providing long-term availability and regulatory alignment. The original Pomona 72987 is obsolete, necessitating transition to one of these alternatives for new designs or system replacements.

Selection between the two Amphenol substitutes depends on cable compatibility requirements. For applications using RG-178 or RG-196 cable series, either substitute is suitable. For applications requiring RG-174 or LMR-100 cable compatibility, the 903-NM289P-51A is the appropriate choice.

The transition from push-on to solder contact termination requires assembly process modification. Both substitutes support the same snap-on fastening mechanism and maintain 50-ohm impedance, PTFE dielectric, and gold-plated center contacts. Operating temperature range narrows from -65°C to -40°C minimum, which may impact applications requiring extended low-temperature performance below -40°C.

Frequently Asked Questions (FAQ)

Q: Can the Amphenol substitutes directly replace the Pomona 72987 without modification?

A: Mechanical and electrical compatibility is maintained for SMB connector interface and RF performance. Contact termination differs (solder versus push-on), requiring assembly process adaptation. Cable attachment methodology must be adjusted accordingly.

Q: What is the difference between 903-NM291P-51A and 903-NM289P-51A?

A: Both are solder-terminated SMB connectors with identical electrical specifications. The primary difference is cable group support. The 903-NM291P-51A supports RG-178 series cables (RG-178, 178A, 178B, 196, 196A, M17/93-RG178). The 903-NM289P-51A supports a broader range including RG-174, RG-188, RG-188A, RG-316, LMR-100, and M17/119-RG174. Select based on your cable specification.

Q: Are there operating temperature limitations with the substitutes?

A: The original Pomona 72987 operates from -65°C to 165°C. Both Amphenol substitutes operate from -40°C to 155°C. Applications requiring operation below -40°C or above 155°C cannot use these substitutes.

Q: Do the substitutes maintain 50-ohm impedance?

A: Yes. Both Amphenol substitutes maintain 50-ohm impedance, PTFE dielectric material, and gold-plated center contacts, ensuring RF performance compatibility.

Q: What is the maximum frequency rating for the substitutes?

A: Both Amphenol substitutes support 4 GHz maximum frequency, compared to 3 GHz for the original Pomona 72987. This provides additional frequency headroom for RF applications.

Q: Are the substitutes RoHS compliant?

A: Yes. Both Amphenol substitutes are ROHS3 compliant, matching the compliance status of the original part.

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