GMC20000 Trimmer Capacitor Equivalent & Substitute Parts

Part Overview

The GMC20000 is a 2.5–7pF trimmer capacitor rated at 175V with top adjustment and through-hole mounting, manufactured by Sprague-Goodman. This component is classified as obsolete, making equivalent substitutes necessary for ongoing production and maintenance applications. The mica dielectric construction provides stable capacitance characteristics suitable for general-purpose tuning and adjustment circuits. Identification of compatible alternatives requires matching the capacitance range, voltage rating, adjustment mechanism, and physical form factor within acceptable engineering tolerances.

Substiute Parts

GMC20000

Sprague-GoodmanIn Stock: 948GMC20000 Datasheet

Current PartRFQ

BFC280800006

Vishay Beyschlag/Draloric/BC ComponentsIn Stock: 2794BFC280800006 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the GMC20000 is based on the following criteria derived from the provided parameters:

Capacitance Compatibility: The substitute must provide a capacitance range that encompasses or exceeds the 2.5–7pF specification of the original part. The BFC280800006 offers 2.5–22pF, which fully covers the required range and provides additional tuning margin.

Voltage Rating: The substitute voltage rating must be equal to or greater than 175V. The BFC280800006 is rated at 250V, exceeding the original specification and providing additional safety margin.

Adjustment Mechanism: Both parts feature top adjustment, ensuring mechanical compatibility with existing tuning interfaces and circuit board layouts.

Mounting Configuration: Both parts are through-hole mounted, maintaining compatibility with PCB hole patterns and assembly processes.

Operating Temperature: The substitute must support the required temperature range. The BFC280800006 operates from –40°C to +70°C. The lower limit (–40°C) exceeds the original requirement (–35°C); however, the upper limit (+70°C) is 15°C below the original specification (+85°C). This represents a constraint that must be evaluated against actual application thermal requirements.

Physical Form Factor: Dimensional compatibility is required for PCB integration. The BFC280800006 has a smaller footprint (0.299" diameter, 0.394" height) compared to the GMC20000 (0.531" × 0.375" × 0.720" height), allowing installation in space-constrained applications.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: BFC280800006 (Vishay Beyschlag/Draloric/BC Components)

The BFC280800006 is the designated substitute for the obsolete GMC20000 based on the following engineering factors:

1. Functional Coverage: The capacitance range (2.5–22pF) fully encompasses the original 2.5–7pF specification, providing complete functional compatibility for tuning applications.

2. Electrical Margin: The 250V rating exceeds the 175V requirement, providing additional safety margin in high-voltage circuit applications.

3. Product Status: The BFC280800006 is in active production, ensuring long-term availability and supply chain stability compared to the obsolete GMC20000.

4. Compliance Status: The substitute is ROHS3 compliant, meeting current environmental and regulatory requirements for new designs and manufacturing processes.

5. Physical Integration: The smaller form factor allows direct substitution in existing PCB layouts with no design modifications required.

Critical Consideration: The operating temperature upper limit of the BFC280800006 (+70°C) is 15°C lower than the original GMC20000 (+85°C). Applications requiring sustained operation above +70°C must verify thermal performance through circuit simulation or prototype testing to confirm adequate margin between maximum ambient temperature and component rating.

Dielectric Material Difference: The BFC280800006 uses polypropylene dielectric instead of mica. This affects temperature coefficient of capacitance and Q factor characteristics. Applications requiring the specific stability profile of mica dielectrics must evaluate whether polypropylene performance is acceptable for the intended circuit function.

Frequently Asked Questions (FAQ)

Q1: Can the BFC280800006 be used as a direct drop-in replacement for the GMC20000?

A: Yes, for applications operating within the BFC280800006 temperature range (–40°C to +70°C). The capacitance range, voltage rating, adjustment mechanism, and through-hole mounting are all compatible. However, the dielectric material difference (polypropylene vs. mica) may affect circuit performance in applications sensitive to temperature coefficient or Q factor. Verification testing is required for temperature-critical or high-Q applications.

Q2: What is the significance of the capacitance range difference (7pF vs. 22pF maximum)?

A: The BFC280800006 provides a wider tuning range (up to 22pF) compared to the GMC20000 (up to 7pF). This allows greater adjustment flexibility in circuit design. However, the minimum capacitance (2.5pF) is identical, ensuring the lower tuning limit matches the original specification.

Q3: Does the smaller physical size of the BFC280800006 affect PCB layout?

A: No. The BFC280800006 (0.299" diameter, 0.394" height) is smaller than the GMC20000 (0.531" × 0.375" × 0.720" height), allowing installation in the original footprint with additional clearance. No PCB redesign is required.

Q4: Are there any compliance or certification differences between the two parts?

A: The BFC280800006 is ROHS3 compliant, while the GMC20000 compliance status is not specified. Both parts have MSL 1 rating (unlimited moisture sensitivity), requiring no special storage precautions. The substitute meets current environmental standards for new manufacturing.

Q5: How does the dielectric material change from mica to polypropylene affect circuit performance?

A: Mica and polypropylene dielectrics have different temperature coefficients and Q factors. Mica typically provides better temperature stability and higher Q values. Polypropylene offers lower cost and smaller form factors. The specific impact depends on circuit requirements. Applications with strict stability or Q factor specifications must evaluate whether polypropylene performance is acceptable through circuit analysis or prototype testing.

Q6: What is the maximum operating temperature limitation of the BFC280800006?

A: The BFC280800006 is rated for operation up to +70°C. The original GMC20000 is rated to +85°C. Applications requiring sustained operation above +70°C must verify that the BFC280800006 provides adequate thermal margin in the specific circuit environment. Thermal analysis or prototype testing is required for applications operating near this limit.