For various reasons you need positive voltage if you're doing traditional power-interruption canopy style sync. I.E. the type of sync which the PowerInjector+Sync will do. This general statement might not be 100% true with the 450i (and perhaps some other more recent radios), but suffice it to say that negative voltages aren't easy to deal with for sync. Because of this requirement the PIPS requires positive power.
On the rackinjector, we support the newer Cambium style sync, which doesn't much care about polarity, and also a polarity agnostic board which also doesn't care about polarity. For this reason, you can feed negative voltages into the rackinjector. Currently, you have to have at least one of the three power supplies feeding the rackinjector set up for positive voltage, and the other two can be positive or negative or whatever you want, depending on the requirements of the expansion cards and the radios. One of the next released products will be a Cambium Sync product in the traditional din mounted PIPS form factor. What is holding us up is that we need to make the "reliant on a positive voltage source for control" requirement go away. Every solution we look at tends to be way more expensive than we want. On Sat, Apr 14, 2018 at 5:53 PM, Seth Mattinen <se...@rollernet.us> wrote: > The PowerInjector plus Sync does *not* work with a telco DC -48V input, > correct? Only the new Rackinjector will? > -- *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 forre...@imach.com | http://www.packetflux.com <http://www.linkedin.com/in/fwchristian> <http://facebook.com/packetflux> <http://twitter.com/@packetflux>
