[time-nuts] HP 5328A Divider / Timebase Output performance

[Bert, VE2ZAZ]

All,

Just to convince myself that my setup is OK, I decided to check my 5370A counter by doing ADEV/MDEV on its own OCXO output, a self-check as recommended in the manual. 50 ohms input on START, HiZ input on STOP, thresholds in preset (~ 0 Volt), common input (internally bridged), rising edge on START, falling edge on STOP. The results are shown in purple. I also measured the HP 8644A OCXO output the same way and got the green plot. No surprise there, more noise because the counter is measuring an external source as opposed to its own timebase.  Based on that, I know that the 5370A counter is not the one generating all that noise on the 5328A divider readings. The one thing I will do just for fun is to measure all the OCXOs I have in-house to see if results will vary a lot. I will try to keep the START-to-STOP interval small using an external delay line on the STOP input instead of bridging inside.