Looking for the HP 59309A Clock, that originally sold in 1970s (1974-1978), for your HP Test Suite (HP-IB) or Time-Nuts Lab? http://www.leapsecond.com/museum/hp59309a/hp59309a.htm Accepts an external Clock reference (1, 5, or 10 MHz, switchable) == One has appeared on eBay, from solanotraders (known New Mexico surplus dealer), eBay auction number: 194344200155 == References for Refresh and Maintenance of the HP 59309A Digital Clock => Safety Capacitors on AC Input, Electrolytic change, Battery Leakage. <= Cleaning up a HP 59309A Digital Clock by Glitch Works November 18, 2020 http://www.glitchwrks.com/2020/11/18/hp-59309a-digital-clock DIY Building the Matching HP K10-599992A Battery Backup. by Mark Greco (HP Museum Forum) May 2021 https://www.hpmuseum.org/forum/thread-16865.html Andrew Bukosêk (Slovenia) Manual links, photos https://bukosek.si/hardware/collection/hp-59309a.html Communicating with the HP 39509A HP-IB Digital Clock using a HP-IB (GPIB) to USB interface from LQ Electronics, called the UG Simple by Dan Veeneman http://www.decodesystems.com/hp59309-code.html Struggling with Basic Component Level troubleshooting (July 2021) https://groups.io/g/HP-Agilent-Keysight-equipment/topic/hp_59309a_digital_clock/84049857 greg, w9gb