PrefaceI made a post in an ADR1000 thread and then realized I needed to backup and regroup. Here is my attempt at regrouping.
Thanks to Jacques and Dieter for getting me back closer to being on track.
I now understand that an ADR1000 EZ board is a DC voltage reference with no MHz (or any Hz) output. I should have looked closer at the schematic and understood it better but I got mesmerized by seeing a SMA connector.
More BackgroundI don't have any big "need" I'm just fascinated with measuring V, I, and R and frequency with as much accuracy and resolution as possible. However my voltnut and timenut interests are offset by the fact that my knowledge only let's me go so deep (not very) at the circuit level, so I'm more at the "system" and "system integration" level, or maybe the "Plug N Play" level.
Having said that, I've come to believe that the LTZ1000 and ADR1000 represent the top of the line or near top of the line for voltage references, so I was (and still am) intrigued by the ADR1000 "EZ" module. As mentioned, I now understand that it's outputting a DC signal - a high quality DC signal but just a DC signal. So presumably it could in turn become a very good PS for something else, but it's not going to generate a 10 MHz frequency (or any frequency). No doubt, kind of a Duh moment for me
But, hey, we all have to start somewhere....
Mission DescriptionWhat I'd like to figure out is how to build something low cost (under $30-$50?) that combines an accurate and stable 10 MHz reference with a suitably stable power supply. The Amazon OCXO modules are as low as $13, so that leaves the power supply, and probably a case. (Additionally, as another project, I'd also be interested in seeing how far I could drive 10 MHz accuracy, resolution, and stability but stay in the $100 to $200 range. At about $200 or less, a BG7TBL GPSDO seems hard to beat, or maybe there is a better benchmark at an even lower price.)
I guess another way of describing my interests would be to say I'm up for experimenting in the $20 to $200 range to see what causes what through measurement, trial and error, posting results, getting feedback, and trying to learn in the process. Kind of metrology 100-101 for rookies.
So maybe the LTZ and ADR are overkill for powering such an OCXO? I probably got too excited thinking maybe I could jump to a top of the line voltage reference and then experiment to see what impact a super PS would have on a "good enough" OCXO.
On the forum(s) I have made some posts about the $13 Amazon 10 MHz OCXO modules. They have unit to unit variation but a good one seems to be stable to about .1 or maybe .01 Hz, or possibly even better.
(I also made some posts awhile back where I learned that measuring and controlling resistance to around 1 milliohm requires 4 wire Kelvin clips and managing ambient temperature - so I'm definitely sold on the impact of temperature mgmt. Having said that, I've found that GPSDOs seem pretty resilient to ambient temperature, so maybe an OCXO without a GPS discipline is a losing battle?)
Back to OCXOs without GPSDOs, I'm pretty sure achieving better than .01 Hz on a 10 MHz signal with just an OCXO requires controlling ambient temperature. To try to confirm this I'm working on putting the OCXO module in a case. Before I get to the case I've been experimenting with the OCXO module to see if a vertical vs horizontal PCB orientation has any impact on performance, but it might be hard to distinguish the physical orientation impacts without first controlling the ambient temp. So maybe I need to first get the module installed in a case that helps deal with ambient temp.
I'm powering the OCXO module with a Korad power supply. Before my "regroup" I was thinking the ADR would be a (much) better power supply. It probably is but at ~$165? for the ADR board it kind of defeats the "low cost" objective. Maybe a LM399 would be a better candidate?
SummaryThe GPSDOs I've experimented with seem to be very accurate and stable for about $200 each. Maybe it's going to be hard to do better for $200. So maybe the question is becoming: is it possible to integrate a $13 OCXO and a ~$30 LM399 to get a ~$50 reasonably accurate and stable 10 MHz reference? (Or maybe if I can get the $13 OCXO module in a case so it's insulated from ambient temperature changes it will improve in accuracy and/or stability enough that the Korad PS isn't a limiting factor?)
I really don't have any big goal here other than experimenting and being able to learn in the process.
Net, net: I'd like to learn what causes what from power supply to OCXO to overall temperature management. If you have any suggestions or guidance, or learnings from other related projects, I'd be very happy to hear whatever you think.
Thanks, EF