Four years ago (2019), I was in the same situation. A gov’t surplus reseller (PA) on eBay listed an Agilent 53131A 225MHz Universal Counter. There were a large number of these models (surplus) being sold a few years ago. Acquired at good (low) price, in very good cosmetic condition (NASA surplus). I changed out the fan and a couple of power supply capacitors. Purchased Option 010 High Stability Timebase Option from Gerry Sweeney (UK). https://youtu.be/RPTQaRoiJyE Use Trimble Thunderbolt (Red, 8-channel) as an external frequency reference. In 2020, just before COVID shutdown logistics, I purchased the 8 MHz prescaler from Cojotech (Romania) for Channel 3 with a nice custom SMA connector. Planned for eventual WiFi 6E coverage. https://cojotech.com Nice counter, that meets my needs. greg === Date: Mon, 13 Mar 2023 14:26:16 -0400 From: John Miller <john@millerjs.org> Subject: [time-nuts] Frequency counter recommendation wanted To: Discussion of precise time and frequency measurement <time-nuts@lists.febo.com> Hey All, I have started a new project and I need trustworthy (frequency counter) that I can rely on for good measurements. I'm looking for something "general purpose" that can also do time interval measurements as well as logging, be it to GPIB, serial, USB, whatever. The ability to operate off of an external timebase would be nice, too, since I do have a known-good rubidium oscillator.

Hi This is very much the reality of the eBay surplus market. TBolts hit the scrap yard in China and they are dirt cheap for a while. Other GPSDO’s do the same thing. Some day they (or another model) will also hit the same scrap yards. Counters / DVM’s / Power Supplies are all in the same cycle. Folks downsize / close facilities and sell off gear. They upsize and sell off the “old stuff” (from 10 years ago) because it’s not compatible with their new setup. Out comes a flood of this or that. 53131 prices have taken a dive about once every 4 years or so ever since 2001. Bob > On Mar 15, 2023, at 10:45 PM, Gregory Beat via time-nuts <time-nuts@lists.febo.com> wrote: > > Four years ago (2019), I was in the same situation. > A gov’t surplus reseller (PA) on eBay listed an Agilent 53131A 225MHz Universal Counter. There were a large number of these models (surplus) being sold a few years ago. Acquired at good (low) price, in very good cosmetic condition (NASA surplus). > > I changed out the fan and a couple of power supply capacitors. > Purchased Option 010 High Stability Timebase Option from Gerry Sweeney (UK). > https://youtu.be/RPTQaRoiJyE > > Use Trimble Thunderbolt (Red, 8-channel) as an external frequency reference. > > In 2020, just before COVID shutdown logistics, I purchased the 8 MHz prescaler from Cojotech (Romania) for Channel 3 with a nice custom SMA connector. > Planned for eventual WiFi 6E coverage. > https://cojotech.com > > Nice counter, that meets my needs. > > greg > === > Date: Mon, 13 Mar 2023 14:26:16 -0400 > From: John Miller <john@millerjs.org> > Subject: [time-nuts] Frequency counter recommendation wanted > To: Discussion of precise time and frequency measurement > <time-nuts@lists.febo.com> > > Hey All, > I have started a new project and I need trustworthy (frequency counter) that I can rely on for good measurements. I'm looking for something "general purpose" that can also do time interval measurements as well as logging, be it to GPIB, serial, USB, whatever. The ability to operate off of an external timebase would be nice, too, since I do have a known-good rubidium oscillator. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com