Fred - I have a number of used, surplus ESE models that I have acquired over the last 20 years. I remember when ESE started with clocks in 1970s (El Segundo Electronics). Some units acquired did not work properly (unknown to dumpster driver/reseller) or were superseded by later models. Majority had a dead backup battery and memory lithium coin cells. ESE schematics shortened troubleshooting for bad ICs — often caused by failed electrolytic capacitors in DC power supply section. I have an ES-188 Master Clock (before 2015), that does not have an 10 MHz option. It sits at my workbench computer station, serves as NTP server for network. I have other GPSDO for 10MHz references. — The “full manual” for ESE products (available to owners, w/SN) has the Schematic diagram and Parts list, including All of Options of ESE models. You are correct that TCXO are the baseline oscillators used in ESE designs. However, ESE only moved to the 10 MHz frequency reference marketplace in the past decade (NAB Show 2016). Historically, ESE Primary market has been the media broadcasting & production industry (NAB, SMPTE time code displays, countdown clocks, etc.) with a smaller market for aerospace/military usage (IRIG-B time codes). In 21st century, they added NTP capabilities for local area networks. ESE web site Their “E” suffix ESE models were introduced in 2015. https://www.ese-web.com/ greg w9gb NOTE: Littlefuse’s decision to EOL the Zilog Z-80 CPU will cause changes for many long-time products. == Date: Sun, 22 Dec 2024 14:25:31 -0800 From: fwbray@mminternet.com Subject: [time-nuts] ESE GPS Clocks To: Time Nutes <time-nuts@lists.febo.com> I've noticed that some of the ESE GPS master clocks have optional 10 MHz and 1 KHz outputs. I'm curious how accurate and stable these are. I assume that at best they use a TCXO and not an oven. Has anyone worked with these units? Thanks and happy holidays. Fred Bray KE6CD ===