[time-nuts] PRS-10 temperature sensitivity (and Lady Heather support)

Mark Sims holrum at hotmail.com
Wed Jul 19 08:09:37 EDT 2017

I recently got in a SRS PRS-10 rubidium oscillator and added support to Lady Heather to control and monitor it.    Attached is a plot of it locking to a Thunderbolt 1PPS.  The plots shown are the TT time tag,  the FC frequency control value, and the case temperature.   Air conditioning was causing 1 degree swings in the case temperature.  The effects of that are clearly visible on the time tag and frequency control plots.

The wobbles in the TT plot are due to the temp changes.  The overall hump is probably due to the disciplining  PLL settling in.

The case temp is reported around 70C, but the SRS supplied heat sink is at 45C.  Their newer heat sinks (anodized black "U" shaped) don't seem to be as beefy as the older aluminum finned ones.

I did find a couple of bugs and issues in the PRS-10 firmware...  setting "verbose" mode should cause all commands that set a value to respond with "OK".   But the LO and LM commands do not.   Also there is no command to read back the "PP" place pulse value (that lets you shift the output 1PPS in relation to the input 1PPS).  Anybody know what the latest firmware rev is?  Mine is 3.24
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