Knox Semiconductor — MIL-PRF-19500 JAN, JANTX & JANTXV legacy diode sourcing (Rockport, Maine)
Knox Semiconductor, Inc. was a small independent JAN diode manufacturer on the mid-coast of Maine — founded in 1974 in Rockport as a silicon wafer foundry, later grown into a DSCC/DLA-certified QML-19500 supplier of hermetic silicon zeners, low-noise voltage regulators, current limiters, and varactor tuning diodes under CAGE Code 61322 / QPL code CEJL. Knox was acquired by MicroMetrics in August 2005 and its MIL-PRF-19500 qualifications have since moved through MicroMetrics, Aeroflex-Metelics, Cobham, and MACOM before landing at VPT Components (Lawrence, MA) in September 2018. Legacy CEJL / CAGE 61322 date-coded JAN diodes still circulate in defense inventories today.
- 1974Founded
- Rockport, MEOriginal HQ
- 61322CAGE Code
- CEJLQPL Code
- JAN → JANHCLevels Held
- LegacyStatus
About Knox Semiconductor
Knox Semiconductor took its name from Knox County, Maine, where it was founded in 1974 and operated for three decades from 12 Industrial Park Road, Rockport (P.O. Box 609), with a plant at 13 1/2 Quarry Road. It began as a merchant silicon wafer foundry supplying grown-junction wafers to third-party TVS and varactor manufacturers. In 1977, Knox introduced its first finished discrete devices — zener diode chips — and shortly afterward developed axial glass package device capability, the foundation for its DSCC-qualified JAN diode lineup.
Knox built its reputation on a narrow, specialized portfolio: very-low-voltage (VLV) zener diodes with the industry's lowest documented reverse leakage at bias currents of 10 mA and below, and ion-implanted abrupt-junction and hyperabrupt varactor tuning diodes for crystal oscillator control. It operated as a DSCC-certified QML supplier to MIL-PRF-19500 under manufacturer code CEJL / CAGE Code 61322. The independent chapter closed in June 2005, when MicroMetrics, Inc. of Londonderry, NH announced its acquisition of Knox — specifically citing Knox's ion-implanted tuning varactor technology as the strategic prize.
Ownership lineage — from Knox to VPT Components
The MIL-PRF-19500 qualifications originally held by Knox Semiconductor did not vanish when the Rockport company was acquired — they moved down a well-documented four-step ownership chain and now sit inside VPT Components' DLA-certified JAN diode line in Lawrence, Massachusetts:
| Year | Event | Where JAN diode production went |
|---|---|---|
| 1974 | Knox Semiconductor founded in Rockport, ME as a silicon wafer foundry | Rockport, ME (independent) |
| Aug 2005 | MicroMetrics, Inc. acquires Knox Semiconductor | Rockport retained as tech / R&D center under MicroMetrics; production consolidated with Londonderry, NH |
| Apr 2007 | Aeroflex, Inc. acquires MicroMetrics; Knox lines roll into Aeroflex Microelectronic Solutions / Metelics division | Sunnyvale CA, Lawrence MA, Londonderry NH (Aeroflex/Metelics) |
| Sep 2014 | Cobham plc (UK) acquires Aeroflex Holding Corp for ~$1.46 B enterprise value | Cobham Advanced Electronic Solutions (CAES) |
| Dec 2015 | MACOM acquires the Aeroflex / Cobham diode business for ~$38 M cash | MACOM Hi-Rel Components at Sunnyvale CA, Lawrence MA, and Londonderry NH |
| Sep 2018 | VPT Components acquires MACOM's Hi-Rel Components business (former Aeroflex-Metelics) in Lawrence, MA | VPT Components, Lawrence MA — where the historic Knox JAN diode qualifications sit today |
The practical implication for defense buyers is straightforward. Knox Semiconductor no longer exists as an operating company or a distinct entry on the DLA real-time QML-19500 list. The Rockport plant is no longer in JAN discrete production. Genuine Knox-manufactured parts remain in circulation, distinguished by CEJL / CAGE 61322 in lot documentation — those parts remain DSCC-qualified product. Current-production equivalents ship primarily from VPT Components for slash-sheet-continuous families (notably MIL-PRF-19500/435 low-noise zeners) and from other QPL-qualified sources for the broader hermetic diode categories.
Historic QPL / QML-19500 status
Knox Semiconductor appeared on printed QPL-19500 revisions for two decades and continued into the electronic QML era. Archived QPL revisions (including QPL-19500-142 held in the DLA Land and Maritime download archive) list the company as:
- Knox Semiconductor, Inc. — manufacturer code CEJL, CAGE Code 61322
- Address on file: P.O. Box 609, Rockport, ME 04856-9999; Plant: 13 1/2 Quarry Road, Rockport, ME 04856
Knox's QPL activity concentrated on silicon low-noise voltage regulator zener slash sheets. The clearest surviving trail is against MIL-PRF-19500/435, which today covers 500 mW silicon low-noise voltage regulator diodes across the 1N4099 through 1N4135 and 1N4614 through 1N4627 device ranges, with C and D voltage-tolerance suffix devices and product-assurance levels JAN, JANTX, JANTXV, JANS, JANHC, and JANKC. Historic QPL entries show Knox holding JANHCA / JANHCB die-level qualifications on the 1N4565A–1N4584A and 1N4614 families under the CEJL code, alongside the encapsulated JAN, JANTX, and JANTXV grades. Additional archived listings show Knox against the /383 low-power zener family and related low-level zener and current-limiter slash sheets. Since the migration of the Knox lines through the MicroMetrics → Aeroflex → Cobham → MACOM → VPT chain, the Knox Semiconductor name has been retired from the real-time QML-19500 listing.
MIL-PRF-19500 quality levels — what JAN, JANTX, JANTXV, and JANS actually mean
MIL-PRF-19500 is the U.S. DoD performance specification for hermetically-sealed discrete semiconductor devices, administered by DLA Land and Maritime, Columbus OH (successor to DSCC-VQ). It defines a stack of ascending product-assurance levels indicated by the prefix on a part number:
| Prefix | Level name | What it adds | Typical use case |
|---|---|---|---|
| JAN | Joint Army-Navy | Baseline qualification against slash sheet, Group A/B/C conformance | Ground defense, ruggedized industrial |
| JANTX | JAN with eXtra Testing | Adds 168-hour burn-in and additional 100% electrical screening | Airborne, avionics, missile |
| JANTXV | JANTX with Visual inspection | Adds 100% pre-cap internal visual inspection | Higher-reliability avionics, tactical space |
| JANS | Joint Army-Navy-Space | Adds wafer lot acceptance, Group E conformance and full space screening | Launch vehicles, satellites, deep space |
| JANHC / JANKC | Chip / die-level | Unencapsulated die screening for downstream hybrid assembly | MIL-PRF-38534 hybrids, custom modules |
Knox is a good example of a manufacturer whose formal qualifications concentrated at the JAN / JANTX / JANTXV / JANHC / JANKC end of the ladder rather than at the space (JANS) end — its die-level product supported downstream hybrid manufacturers building to MIL-PRF-38534 assemblies. On top of individual part-type QPL qualification, the DoD now operates the line-level Qualified Manufacturers List (QML) framework that current QML-19500 suppliers such as VPT Components are audited against.
Knox Semiconductor's historic MIL-PRF-19500 product portfolio
Knox's device portfolio was narrower than the big multi-line JAN houses but well differentiated inside the categories it did address. In line with the sourcing intent of this page, the families below are the ones we look for in inventory, described by device type and slash-sheet family rather than by individual JAN part number — specific part-number availability is confirmed on quote.
Low-noise silicon voltage regulator zeners (MIL-PRF-19500/435 lineage)
Knox's flagship JAN family covered 500 mW silicon low-noise voltage regulator zener diodes in axial hermetic glass packages, feeding what today is the MIL-PRF-19500/435 slash sheet (1N4099–1N4135 and 1N4614–1N4627 device ranges, with 5%, 2%, and 1% voltage tolerances). Knox held JAN through JANHC/JANKC qualifications on this family, including double-plug metallurgically-bonded construction designed for low reverse leakage and low broadband noise density — a direct predecessor of the VPT Components low-noise regulator zener line that currently ships against /435.
Very-low-voltage (VLV) low-level zener diodes
Knox's public catalog described a distinctive family of Very Low Voltage Diodes in the K120–K510 numbering range — nominal Zener voltages from 1.2 V to 5.1 V at Iz = 10 mA, with sharp-knee low-impedance behavior and very low reverse leakage (typically 0.05 µA). Devices were qualified over −65 °C to +175 °C in DO-7 glass axial packages with 250 mW dissipation at 50 °C ambient, targeting battery-conservation-critical military applications where standard zeners with nominal breakdown above 5 V could not operate.
Silicon current-limiter (constant-current) diodes
Knox produced JAN, JANTX, and JANTXV silicon current-limiter diodes in the 1N5283–1N5314 family and 1N5300 branch, still visible in surplus inventories under CAGE 61322. They are used as compact two-terminal current sources in reference circuits, LED drives, and low-power biasing networks.
Abrupt-junction and hyperabrupt varactor tuning diodes
A significant part of Knox's intellectual property was its ion-implanted abrupt-junction and hyperabrupt varactor tuning diode technology — the specific asset MicroMetrics cited when announcing the 2005 acquisition. Devices such as the 3022 hyperabrupt series were designed for crystal oscillator control with roughly 10:1 capacitance ratios across −0.3 V to −4 V dc bias, in SOT-23, SOD-323, and SOD-523 surface-mount packages. General-purpose abrupt varactor families (K-series, MV-series, and datasheet numbers such as 1N5148 and V956E) covered the broader tuning-diode market including ultra-low-leakage variants.
Unencapsulated die: JANHC and JANKC for hybrid assembly
Because Knox held die-level qualifications, hybrid manufacturers building to MIL-PRF-38534 could source Knox parts as JANHC (chip-level) and JANKC (known-good-die), appearing on QPL-19500 as JANHCA / JANHCB entries on /435 and related low-power zener sheets.
How Hybrid Electronics sources legacy Knox Semiconductor JAN parts
Hybrid Electronics Corporation is a Sanford, Florida-based independent stocking distributor and sourcing agent, founded in 1981 as Knight Electronics. Because Knox is a discontinued lineage, we treat it purely as a sourcing engagement: locating genuine CEJL / CAGE 61322 date-coded Knox product in third-party inventories, or cross-referencing to a current QPL-qualified source (typically VPT Components) for the same slash sheet where new production is required. We are not an authorized distributor, agent, licensee, or franchised partner of Knox or of any successor entity in the MicroMetrics / Aeroflex-Metelics / Cobham / MACOM / VPT chain.
Obsolete Knox-brand JAN inventory
Original Rockport, Maine-manufactured JAN, JANTX, JANTXV, JANHC, and JANKC parts under CAGE 61322 / CEJL. Sourced from OEM excess, contract manufacturers, and long-term storage; date-coded lot traceability typically available.
Slash-sheet cross-reference
Have a Knox part number but no supplier, or a MIL-PRF-19500 slash-sheet reference (/435, /383) without a settled manufacturer? We quote current-production VPT Components equivalents and other QPL-19500 sources on the same slash sheet.
Successor-brand JAN sourcing
For designs that formerly used Knox parts, we source across the current QML-19500 manufacturer set — VPT Components for the direct Aeroflex-Metelics lineage, plus Microsemi/Microchip, Semtech, Sensitron, Semitronics, and Diodes Inc.
Frequently asked questions
Is Knox Semiconductor still in business?
No — not as a standalone company. Knox Semiconductor, Inc. was acquired by MicroMetrics, Inc. in August 2005, then rolled through Aeroflex (2007), Cobham (2014), and MACOM (2015). In September 2018, VPT Components acquired the former MACOM Hi-Rel Components business at Lawrence, MA — where the JAN diode qualifications inherited from the Knox lineage sit today.
What was Knox's CAGE code and QPL manufacturer code?
CAGE Code 61322 and QPL-19500 manufacturer code CEJL. Legacy JAN, JANTX, JANTXV, and JANHC/JANKC parts stamped or lot-coded under these identifiers are genuine Knox-manufactured product from the Rockport plant.
Which MIL-PRF-19500 slash sheets did Knox hold qualifications against?
Most visibly MIL-PRF-19500/435 (500 mW low-noise zener voltage regulators, 1N4099–1N4135 and 1N4614–1N4627, with JAN through JANKC levels) and related low-level zener and current-limiter slash sheets. Historic archived QPL revisions also list Knox against /383 among other zener families.
Where is the Rockport, Maine plant now?
The Rockport site was retained as a MicroMetrics tech / R&D center immediately after the August 2005 acquisition, but its JAN discrete production was progressively consolidated south into MicroMetrics' Londonderry NH fab and later the Aeroflex-Metelics Lawrence MA site. The Rockport plant has been dormant with respect to MIL-PRF-19500 discrete production since that phase.
Does Hybrid Electronics stock legacy Knox Semiconductor parts?
We source legacy Knox JAN, JANTX, JANTXV, and JANHC/JANKC diodes from OEM excess, contract manufacturer surplus, and long-term storage inventories. Because Knox is a discontinued lineage, availability is by lot and date code; contact us with your part number and quantity for a stock check.
Is Hybrid Electronics an authorized Knox or VPT distributor?
No. Hybrid Electronics is an independent stocking distributor and sourcing agent. We are not a distributor, reseller, agent, licensee, partner, or authorized service provider of Knox Semiconductor, Inc. or of any successor entity in the MicroMetrics / Aeroflex-Metelics / Cobham / MACOM / VPT Components chain. All trademarks are property of their respective owners.
Trademark and affiliation notice. All company names, product names, and trademarks referenced on this page are the property of their respective owners. Hybrid Electronics Corporation is an independent stocking distributor and sourcing agent; we are not a distributor, reseller, agent, licensee, partner, or authorized service provider of Knox Semiconductor, Inc. unless expressly stated. Component sourcing is subject to availability and inspection. Hybrid Electronics does not sell counterfeit parts and does not offer repair services. MIL-PRF-19500 and JAN quality-level designations are administered by the U.S. Defense Logistics Agency (DLA).