Hi Rick, It is our good fortune that some years ago Agilent/Keysight released the schematics to the 53131A/53132A counters: http://literature.cdn.keysight.com/litweb/pdf/5989-6308EN.pdf
Have a look and see if you can recreate the details that you remembered. I too have noticed on some tests that the counter seems to ruin the benefit of a good external timebase. This is even more true of the newer 53230-series counters. Maybe get rid of the PLL and use a int/ext toggle switch like the 70's. So it would be nice if you or other circuit experts on the list could point out the flaw(s) -- I'm sure a couple of time nuts would even be willing to mod their 53132A boards based on some suggestions on what to try. Thanks, /tvb ----- Original Message ----- From: "Richard (Rick) Karlquist" <rich...@karlquist.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Sunday, April 12, 2015 8:30 AM Subject: Re: [time-nuts] Ultra High Stability Time Base Options for 53132A > On 4/12/2015 1:03 AM, Adrian Godwin wrote: >> What caused that degradation ? I'm interested in dos/don'ts for best use of >> a 10811. >> > > I don't remember the details much after 25 years, but > basically they have a distribution amplifier that > allows for internal or external 10 MHz and what I > remember is that I looked at the schematic and > concluded that no one with a background in precision > time and frequency would design it that way. And > it turned out that the person who designed it did > not have any such background. I vaguely require > some measurement that had disappointing results that > caused me to want to look at the schematic of it > in the first place. > > Rick _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.