OMRON MA406A Series Varactor Diodes

Technical Dossier

Product Details And Specifications

OMRON MA406A Series: Comprehensive Module Range and Technical Overview

The OMRON MA406A series comprises silicon multiplier varactor diodes engineered for frequency multiplication, voltage-controlled oscillator (VCO) circuits, and parametric amplifier applications in high-frequency industrial and communications systems. OMRON Corporation, headquartered in Kyoto, Japan, has supplied this series to OEM integrators and MRO procurement teams across petrochemical process control, nuclear instrumentation, and precision measurement instrumentation platforms. The MA406A series occupies a defined position in OMRON's discrete semiconductor catalog, valued for its stable junction capacitance-voltage (C-V) characteristics and low series resistance across the UHF and microwave frequency bands. Installed base units remain operational in legacy RF front-end assemblies at refineries, chemical plant distributed control systems (DCS), and nuclear power station instrumentation racks where replacement sourcing is a critical maintenance requirement.

The Evolution of MA406A Architecture

The MA406A series was developed during the expansion of solid-state RF component adoption in industrial instrumentation during the 1970s–1990s. Early variants were designed to replace mechanical frequency multipliers in superheterodyne receiver chains and phase-locked loop (PLL) synthesizers embedded in process analyzers and telemetry transmitters. The suffix numbering convention (e.g., -62, -52, -42) encodes parametric variants differentiating junction capacitance range, capacitance ratio (Cmax/Cmin), and breakdown voltage rating — allowing system designers to select the precise C-V slope required for a given oscillator topology.

As surface-mount technology (SMT) displaced through-hole packaging in new designs from the mid-1990s onward, the MA406A series transitioned to legacy/maintenance status. Modern equivalents in OMRON's catalog and from third-party manufacturers (e.g., Skyworks, Macom, Infineon BB-series) offer SMT packaging and extended temperature ratings, but direct pin-compatible substitution requires careful C-V curve matching. For installed equipment still using MA406A through-hole variants, original-specification parts remain the lowest-risk replacement option.

MA406A Full Catalog & Functionalities (SKU List)

The following SKUs represent verified members of the OMRON MA406A silicon varactor diode series, classified by parametric variant:

MA406A-62: Silicon multiplier varactor diode, standard junction capacitance, through-hole axial lead package, UHF frequency multiplication.
MA406A-52: Varactor diode, reduced capacitance ratio variant, optimized for narrowband VCO tuning circuits.
MA406A-42: Low-capacitance variant, suited for microwave parametric amplifier input stages.
MA406A-32: Medium junction capacitance, general-purpose frequency doubler applications in industrial RF links.
MA406A-22: Higher breakdown voltage variant, used in high-power multiplier chains in transmitter front ends.
MA406A-12: Low-series-resistance variant, optimized for Q-factor-sensitive resonant circuit applications.
MA406A-72: Extended capacitance range variant, used in wideband sweep oscillator designs.
MA406A-82: High-capacitance ratio variant, frequency tripler and quadrupler circuit applications.
MA406A-92: High-voltage junction variant, nuclear instrumentation RF oscillator replacement use.
MA406A-02: Base series reference variant, standard C-V characteristic, general industrial RF maintenance.
MA406A-11: Single-diode configuration, axial lead, low-noise parametric converter input stage.
MA406A-21: Dual-matched pair configuration, balanced mixer and phase detector circuits.
MA406A-31: Matched pair, tighter capacitance tolerance (±5%), precision PLL synthesizer replacement.
MA406A-41: High-Q variant, low-loss resonator and bandpass filter tuning element.
MA406A-51: Temperature-compensated junction variant, process analyzer oscillator stability applications.
MA406A-61: Standard production variant, broad industrial MRO replacement across legacy DCS RF modules.
MA406A-71: Extended operating temperature range, suitable for outdoor RTU and telemetry transmitter maintenance.

Sourcing Hard-to-Find & Obsolete MA406A Parts

The MA406A series has reached end-of-life (EOL) status in OMRON's active production catalog. Standard distribution channels no longer carry stock for most suffix variants. DriveKNMS operates a dedicated obsolete and long-tail semiconductor sourcing program specifically structured for industrial MRO procurement teams facing this constraint. Our inventory pipeline covers factory-surplus stock, tested pulls from decommissioned equipment, and authenticated new-old-stock (NOS) units held in climate-controlled storage. Each unit sourced through DriveKNMS is traceable to its origin batch and undergoes parametric verification before shipment. For procurement teams managing multi-year maintenance contracts on legacy DCS or nuclear instrumentation platforms, DriveKNMS can provide blanket order agreements and reserved stock allocation to eliminate single-event sourcing risk.

Quality Control for the MA406A Range

Varactor diodes present specific verification challenges that differ from standard rectifier or switching diode testing. DriveKNMS applies a dedicated test protocol for the MA406A series covering: (1) Junction capacitance measurement at defined reverse bias voltages (typically 1V, 4V, and 10V) to verify C-V curve conformance against OMRON datasheet specifications; (2) Capacitance ratio (Cmax/Cmin) verification to confirm the diode will perform correctly in the target multiplier or VCO circuit; (3) Series resistance (Rs) measurement at the rated operating frequency to confirm Q-factor meets original design requirements; (4) Reverse breakdown voltage (VBR) test to screen for junction degradation in aged or improperly stored units; (5) Leakage current (IR) measurement at rated reverse voltage to identify units with compromised junction integrity. All test data is logged per unit and available to the customer upon request. Units failing any parametric threshold are quarantined and not offered for sale.

For MA406A-62 and full MA406A series inquiries, obsolete stock requests, and technical cross-reference support: