Does anyone know of a high power 28V or 26V POE injector?
I have a long cable run for which 24V is not enough and 30V is too much - I can’t find anything in between.
you can use 30v and put 4 diodes for a 2.4v drop.
What RB you use? How you know that 24V PSU is not enough? How about power via Jack over 2x1,5mm2 power cable?
Laird/PacWireless 12w active splitter with isolation. POE-24s-afi
You feed it with 48vdc POE. Then mount the splitter in your outdoor enclosure.
They also have 5vdc, 9vdc, and 12vdc versions.
I have never used them but they sound like a good idea. If 12 watts is enough for your application.
Tom
RB433AH. I know 24V is not enough because when both radio cards in the routerboard transmit at maximum power, it reboots. When only one transmits, or both transmit at low power, everything is ok.
I have to use POE, I can’t replace or add any cables.
I’ll give it a try if I can’t find anything else and can manage to fit the splitter in the enclosure.
Thanks for the idea.
You have a power problem. Power at the top is what you need here. You don’t have a voltage problem since RB433AH will run just fine as low as 12vdc. The voltage drop over long DC cable runs reduces the power at the top. You didn’t say which 24vdc POE device you had used. If it is the Pac Wireless POE-24i or the Mikrotik 18POW, they put out 19 watts at the bottom (24vdc x .8amp=19watts). Assume a 4 volt drop over a long run and the power at the top is reduced to 16 watts. (20vdc x .8amp=16watts)
That might not be enough for an RB433AH and two XR type radio cards at full power.
Have you tried something with more power like the 24HPOW 38 watt 24vdc power supply?
http://www.roc-noc.com/product.php?productid=89&cat=3&page=1
Use that with a passive POE adapter to fix your power problem.
Tom
12 watts is only enough power for a single high power radio card and a RouterBoard so it won’t fix your problem.
Tom
I’m using the pac wireless 24V 50W POE injector. The problem is that the voltage drop over the long wire is too big. Recall that the voltage drop increases as the current increases.
maybe the quality of the cable is not so good?!
Besides, it is a good cable, but it’s long.
I’m bumping this up in case there is a new product out there.
how many volts do you end up with at the other end when using the 24v PoE adapter? Test it while it’s running …
The RB433AH is reporting 19.7 V under light load.
You can use a 48-60v Power Supply with a passive PEO, and build your own DC-DC converter to regulate at 12 or 24 volt.
The higher the voltage, the lower the power loss over distance.
Hence why electric companies transfer using tens of thousands of volts.
All the small voltage regulators I can find that output 12V or 24V, take only up to 35V as input.
The RB433AH should keep running all the way down to 10vdc. I doubt that the increased load is causing an additional voltage drop of 9.7 volts. Perhaps the jitter of the voltage is causing crashes. Have you tried a large capacitor across the the power lines and close to the RouterBoard to stabilize the voltage?
I would try to recreate this in the lab with another RB433AH and a bunch of wire. Then you can look at the power with a scope and see what is happening.
Tom
RB consumes pulse current.
If the voltmeter shows 12 - not always so.
Better use additional phantom power.
As far as 35v max input:
Use a voltage divider to lower the input voltage of the Regulator.
http://en.wikipedia.org/wiki/Voltage_divider