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  • EXCELLENT VALUE wired only for 802.1AF MODE-B

    posted by radcomtech on 03/29/2012

    Involvement:Expert (understands the inner workings) - Ownership:1 week to 1 month


    OK so its very good value for $14! Some Cisco and AVAYA Inline PoE 802.3af-2003 adapters are priced at 9x or more. (25Watt category)

    Under the standard, "MODE B" wiring indicates that cable pins 4&5 (pair 1) and pins 7&8 (pair 4) carry the actual power at 48 VDC. There is a specific "announce" sequence in the standard that allows Powered Devices (PD) to "detect" which power mode is being used.
    The device was designed for 10baseT and 100baseTX, it works at 1000baseT for shorter cable runs.

    The device will work with older Cisco and Nortel VoIP phones which default to MODE-B 802.3af anyway (4&5 are +, 7&8 are - or "return".


    The problem with the DX product is that it is not "smart in that it will NOT perform the smart "announcement" stages called for in the actual standard, where a PD is "told" in the first few seconds of connection which standard is followed, which is why most devices will REJECT this PoE adapter.

    The device definately causes issues with 1000baseT system wiring, and smart switches see it as a problem from about 10meters onwards.
    No real ULc and correct CE markings.
    Worked at 240VAC ok but gets hot


    Wow, this adapter actually pumps 48 VDC at 500 mA no problem and it has an overcurrent shutdown (about 5 seconds or so) . LOTS of POWER. JUST WHAT I NEED FOR MY PTP clients.

    Measured 48.5 VDC
    ran 100 OHM load (489mA) for 30 minutes
    (carbon load in oil-immersion cooling)
    seems to cutoff/protect at ~600mA ~40VDC


    its not "PoE-smart" but it does MODE B and its $14! least expensive working MODE B "PSE" on the world market.
    Excellent for TELECOM Timing and other outside plant DCE's that are powered by 48VDC

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