Another nice plot! It looks like after 2am you see temperature swings of 1.5 degF roughly every 30 minutes? Correspondingly, the EFC line which is nominally ~2.8vdc sees swings of +-50 uV?
On Monday, 7 November 2016, Bob Stewart <[email protected]> wrote: > Hi guys, > First of all, thanks for the additional responses. I was a bit angry and > rude yesterday, and I figured this thread was over. Thanks for staying > with me. > I haven't had time to look over the data etc in your responses. I'll do > that and get back to the list if appropriate. > > I spoke to Attila and Azelio offline last nite and from their input, I > decided to hook up the 3456A and collect some data, which is in the plot > attached. As usual, I've modified one of my standard plot scripts, so > there is some extraneous data that wasn't removed. > > First for our purposes is the thin red line, which is the DAC value locked > at 0x734B0. The orange trace is the temperature adjusted so that each step > of 10 on the right hand Y tics is one degree F. The dark blue trace is the > EFC value read by the 3456A. It has been multiplied by 100,000 and then > had 282600 subtracted. This leaves just the LSD scaled at 1:1 on the right > hand Y tics. > There's something interesting on the far right hand side where the > temperature goes low and stays there. The DVM value follows it down, but > then recovers while the temperature stays down. I'm not sure what to make > of this. Either then OCXO is making up for the temperature change by > increasing the temperature, or the 3456 is compensating for it after the > fact. In either case, the EFC seems to only follow the transient > temperature changes, and doesn't actually track the temperature on the > board. > > So, to my eye, after 14 hours, there is only a dependency on thermal > transients. I'll leave it running for some time yet, but the EFC doesn't > seem to be drifting in any meaningful way at this point, other than in > relation to temperature changes. > > Note: I used a shielded twisted-pair with the usual clips attached to > ground and EFC in my GPSDO. On the 3456, the two leads go to the > appropriate volts inputs, and the shield goes to the ground input. The > "guard" switch is out, which is the off position. There is no shield > connector on the DUT side. > > Bob > > ----------------------------------------------------------------- > AE6RV.com > > GFS GPSDO list: > groups.yahoo.com/neo/groups/GFS-GPSDOs/info > > > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
