[time-nuts] Questions on Nortel Trimble NTBW50AA GPSTM

[Mark Sims]

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.