TL:DR The OCXO preamp seemed to have a very high current draw, looking at the specs of the components we should expect 1.08 A during warm up and 0.74 A thereafter.
It is working as expected.
Anchal installed a new 18VDC power strip under the table for suppling various electronics from a single (common grounded source). I plugged the OCXO preamp (LIGO-D1600008), for 36 MHz and 37 MHz RF generation into the strip and found that the 18V supply hit its current limit.
Components inside box are pictured below. The Wenzel crystal oscillators have a 5 W draw in the first 5 minutes as they heat up (for their 15 V supply). In total the initial current draw was 1.1 A between the pair of independent frequency sources. This load also included voltage regulators and amplifier units which should be about 200 mW per channel. All up this is a requirement of 1.08 A during warm up and 0.74 A thereafter.
After 5 minutes in the current draw had dropped back to 0.8 A. So this was about right. I bumped up the current limit on the Sorensen supplies.