I’ve got a wireless installation that will require a PoE Extender. I’m planning on using a CopperLink 2110/P. Radio is a RB711-2HnD in a IT ELITE SRA24014 DUAL - 14dBi panel antenna 2,4GHz shell.
My question is how far into the Cat5e run should I employ the Extender?
Thanks
Edit:
Total Cat5e run from PoE to Wireless Radio is in the neighborhood of 550’, possibly around 600’.
Each Ethernet segment needs to be within 100m / 328 feet so in your case you will want the extender to be roughly at the half way point and check that neither segment exceeds 100m port to port including jumper cables etc. .
Awesome!
Thanks for your help.
Double check the specs of the extender. It looks like the PoE is 802.3af so some additional conversion required for use with RouterBoard.
I am now looking at this extender:
http://www.l-com.com/power-over-ethernet-ieee-8023af-poe-extender
Still 802.3af though…
What kind of additional conversion would be required?
Guy over on the UBNT forum had success with a 600’ run. Of course that being UBNT Equipment…
I’d actually suggest using a RB750UP as a ‘PoE-extender’.
It uses, and provides, exactly the sort of passive PoE that the RB711 needs; and gives you an active device in the middle to monitor and test from.
Plus, they are fairly cheap.
–Eric
That might work in some situations but 802.3af systems can have an advantage over extended distances due to the lower voltage drop / power loss associated with lower current for any given loop resistance.
Sure, but if you are using a 12-ish to 24-ish volt passive PoE device at the end anyway, then the efficiency losses of the DC-DC converter will negate a good bit of that benefit.
The power supply that comes with the RB750UP has more than sufficient amperage available to drive several devices, even with a combined cable length far greater than 600ft; and the voltage drop won’t be significant with an end device that pulls <250mA. I have several systems where a RB750UP is fed PoE over a 250-300ft cable run, and then supplies power to four UniFi units at 50-300 additional feet. They work great.
Not to mention that the RB711-2HnD will work down to 8 volts. You could probably chain four (or perhaps even more) RB750UPs with 300ft of cable between each one, and still have sufficient voltage at the end to drive a 8V/250mA device. (I haven’t actually tried that)
–Eric
If it isn’t broken then don’t fix it… 
On new installs I prefer to use a system which can continue to work on 1000BaseT circuits. The power loss is is proportional to the square of the current so higher voltage systems tend to win out even with the losses from DC<>DC conversion and modern DC<>DC converters can attain very high efficiencies.!
Of course you are right, in that a 802.3af (or now/soon .3at) system is ‘better’ in many cases…
If you are trying to come up with a ‘cookie-cutter’ solution that will work in the widest range of situations.
If you are using .3af gear.
If you need to go a really long distance.
If you have high current draw.
If you need gigabit.
Etc…
But none of that seems to be true here. What stewie01 describes is very simple, and easily accomplished with a RB750UP (or probably even one of the new RB951Ui units), cheaper than could be done with an .3af extender and DC-DC converter.
Given the minimal power requirements of the RB711 series, the voltage drop will also be minimal, and well within the range the gear will tolerate. Combine that with the DC-DC losses (especially from a cheap converter), and any power savings you gain from using 48v on the wire will be negligible (this would obviously not be true for significantly higher-power gear).
As you said, if it isn’t broke then don’t fix it. Why add unnecessary extra parts and use unmanaged devices; when a simpler, cheaper, and managed solution exists (from the same manufacturer as the device being powered, even)?
–Eric
You can use a smart extender like this from Panoptic to extend your run: http://www.panoptictechnology.com/network-poe-extenders/
Then you can use an adapter like this to power the AP: http://www.panoptictechnology.com/network-smart-adapters-mikrotik/