Pretty much all the telecom GPSDO's are driven by an on-board, isolated DC-DC converter. Some are 24V nominal input, some are 48V (a few are even 18-72V). The '+' / '-' designation is pretty much irrelevant since the converter inputs are isolated and are not referenced to chassis ground... and there is a series blocking diode to make them semi-idiot-proof. You do need to get the proper polarity of the power supply to the inputs to the converter. All mine have a center positive barrel jack wired directly to the input diode on the board.
Pretty much all the telecom GPSDO's are driven by an on-board, isolated DC-DC converter. Some are 24V nominal input, some are 48V (a few are even 18-72V). The '+' / '-' designation is pretty much irrelevant since the converter inputs are isolated and are not referenced to chassis ground... and there is a series blocking diode to make them semi-idiot-proof. You do need to get the proper polarity of the power supply to the inputs to the converter. All mine have a center positive barrel jack wired directly to the input diode on the board.
