You can power it up on the lab bench making sure the case is insulated. Measure from each side of the power pins to the case.
If you get a solid 48 from one side to the case, then that is the polarity. If it is a solid –48 from – input to the case it is a –48 radio. Ditto for the positive side. If the readings from the case to the power inputs is all over the place and erratic, then it is probably floating and you don’t have to worry about the polarity. From: Carl Peterson Sent: Monday, May 01, 2017 8:39 AM To: [email protected] Subject: [AFMUG] ignitenet fiber fusion switches DC power Does anyone know if these support -48VDC? It doesn't look like - or + are referenced to ground, but before I blow something up or create a stupid issue down the road, I figured I'd ask.
