Product Overview
Siliconix DN423 Dual JFET - Matched Pair, Hermetic TO-71 Metal Can, Gold Leads, NOS
Condition
Unused NOS. The metal can body is clean and pristine with no corrosion. Gold-plated leads are straight and bright. Photo-confirmed stamped markings include the DN423 part designation and the classic Siliconix interlocking hook logo. Evaluation: Visual inspection only. Function testing not performed.
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Product Overview
Siliconix DN423 - a monolithic dual N-channel JFET in a hermetically sealed TO-71 6-lead metal can with gold-plated leads. The two JFETs are fabricated on a single piece of silicon inside one sealed enclosure, giving them inherent thermal tracking and tight parametric matching that discrete pairs cannot replicate. The photos show the specific unit you will receive.
Key Features
- Monolithic dual N-channel JFET - both devices on a single silicon substrate
- Hermetically sealed TO-71 6-lead metal can package
- Gold-plated leads - photo-confirmed straight, bright, no corrosion
- Approximately 7mm body diameter, under 10mm overall - confirmed by scale in photos
- Stamped markings confirm DN423 part designation and Siliconix maker's mark
- Inherent thermal matching - shared substrate means both JFETs track temperature together
- Drop-in replacement geometry for original PCB footprints requiring this package
Applications
- Restoring the differential input stage of a Fluke 8400A or 8375A digital voltmeter where the original matched pair has drifted or failed - this is the correct original device geometry
- Repairing vintage high-end preamplifier front ends where the monolithic construction is required to maintain the circuit's noise floor and thermal stability
- Calibration bench work where a technician needs to return an instrument to factory-spec performance without redesigning the input stage around a discrete substitute
- Experimental low-noise differential amplifier builds where makers want the thermal-canceling advantage of a monolithic pair without sourcing a matched discrete pair and hoping they track
- Vintage audio circuit restoration projects where the original layout calls for a TO-71 footprint and a modern substitute would require trace modifications
Frequently Asked Questions
Is this the correct replacement for the input stage of a Fluke 8400A or 8375A?
The DN423 is specifically identified in research as the original dual JFET used in the differential input stages of the Fluke 8400A and 8375A. The part number and TO-71 6-lead package are confirmed. Verify against your specific instrument's service documentation before installation.
What makes a monolithic dual JFET different from just buying two matched discrete JFETs?
Both JFETs in the DN423 are built on the same piece of silicon inside one sealed can. Because they share a substrate, they heat and cool together. That thermal tracking is what eliminates drift in a differential amplifier. Two discrete JFETs - even tightly matched at room temperature - sit in different physical locations and respond to temperature changes at different rates. The monolithic construction is not a convenience feature; it is the functional requirement in circuits designed around this part.
Is a manual or datasheet included?
Not included.
What is the lot code visible on the can?
Photo evidence confirms partial markings including the DN423 designation and the Siliconix interlocking hook logo. A 1975-era lot code is referenced in catalog records for this part. The full stamp detail is partially visible in the product photos.
One sealed metal can. Two perfectly matched JFETs. The kind of part that kept a generation of precision instruments honest - and the one a serious tech reaches for when nothing else will hold calibration.
