I've been experimenting with various configurations more or less non-stop.

For the DOC020V, the short term stability doesn't seem to vary a whole lot when powered with the SC189Z vs an LDO. The folks at Connor Winfield tell me that the oscillator portion of their OCXOs is separately regulated internally, so that makes some sense. So 3 mV P-P of ripple for an OCXO looks like it should be within acceptable limits. That ought to figure, given that they draw more than 300 mA steady-state. It's unreasonable for a high current device to be too picky about noise and ripple, IMHO. I suppose you could make some sort of ratio of ripple tolerance to supply current as a sort of "sensitivity" metric. I don't know if anyone's done anything like that or not.

But for the DOT050V, things appear to be quite different. The spec sheet says that they draw 10 mA, and it's clear that 3 mV P-P of ripple has an impact. This graph shows two DOT050Vs, one supplied with an LDO, and one with the SC189Z:

You can plainly see a half an order of magnitude difference between the two. And to get the SC189Z to even have 3 mV P-P of ripple I had to throw a 39 ohm resistor across its output. At lower loads, the ripple was much worse.

I had hoped to come up with a unified architecture for the DOC and DOT variants, but that's just not going to fly. Using an LDO for the OCXO barely gives the oven enough current for its startup load and its inefficiency just adds another heat source to the board. Using a switcher for the TCXO just isn't going to be clean enough, and the whole thing draws so little current that the inefficiency of an LDO is hardly noticeable.

But at the end of the day, the short term stability difference between the DOC and DOT series just don't justify the extra $20, much less the cost and bother of two different boards.

On the other hand, the OH300 series promises perhaps an order of magnitude improvement over the DOT050V. That oscillator, with the switcher regulator, may be the winning design for a "premium" version, with the DOT050V being the "budget" model. We'll know more about that later today, since the board for an OH300 variant is due to arrive.

Once that variant's physical fit and finish in the new chassis is verified, then I'll push through the LDO powered DOT050V design.

Meanwhile, version 1.4 of the board with the DOT050V is available in the store and offers darn good performance for the price, IMHO...