David Chandler, Christopher Leissner, Peter Cash, Microchip

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The 5071A primary frequency reference was first introduced in 1992. Due to its exceptional stability, accuracy, reliability and simplicity of operation, the 5071A has become an industry icon, with over 500 units having contributed to TAI since 2016. The 5071A is also widely deployed in GNSS ground stations, calibration and test services, radio astronomy, government and defense systems, and critical infrastructure. Unfortunately, like all electronics, maintaining manufacturability with an increasing rate of end-of-life components has been a challenge. Adding to the challenge is the sheer number of components required to build a 5071A, and the influence even minor changes in components can have on a unit with a frequency accuracy of 5E-13 and a flicker floor of 1E-14. In 2017, a major multi-year effort was undertaken with a goal of maintaining 5071A production through at least 2035 while also ensuring CE compliance. This time frame was chosen based on overall industry trends for alternative technologies including optical and ion clocks, and when we predict likely mass-market acceptance of the alternate solutions based on future manufacturing process maturity and demonstrated reliability. This paper provides an update on the refresh, including the project overall plan, the status and test results for Allan deviation and other key parameters.