DMC modules used for 24GHz transverter (see my other post here) need (+8.4V) and (-5.0V) voltages, where the (-5V) must be applied first.
I have built a simple power supply that honors this requirement. Original idea came from another HAM's web site. I liked this simple solution with a Zenner Diode, so I adapted it for my needs:
First test results were good. Note that output voltage (+8.4V) can be adjusted by changing resistance of R3. In my case, I have used two resistors in parallel. PCB provides enough space for both of them.