IC-905 – first impressions

After having tried the IC-905 for some days here the first facts:

The most important (that is nowhere really mentioned): the communication between the control unit and the RF unit is done via Ethernet – even via IP. 🙂 In every datasheet is only written something about „LAN cable“ and PoE. It also could have been something proprietary beyond Ethernet that would not allow any switching architecture or fiber connections between both devices. But everything is fine.

The IP-Adress of the control unit is and the RF unit The communication seems to be done with TCP ports 50004, 50006 and 50007.

So any setup with low latency that transparently bridges both interfaces is suitable for operation.

Discovered disadvantages: ATV AF Subcarrier Frequency can’t be set to common 5,5MHz. This issue has already been reported to ICOM.

The diode matrix consisting of 18 diodes that might allow any frequency expansion is located on the bottom side of the main unit. Further investigations will be done.

The PoE topic: whether it is active or passive PoE I couldn’t really determine for now but as I can’t measure any resistance values that are usually necessary for active PoE I guess it is passive.


Pin 1,2 / 4,5: +56V – Pin 3,6 / 7,8: –

Update: I was finally able to power the RF unit through an external injector with the above mentioned polarity. Installing a network isolator right behind the control unit in order not to damage your next network equipment is necessary.

example: indoor unit <-> network isolator <-> switch (non-PoE) <-> injector <-> RF unit

another note: the RF unit is not switched on by simply powering it through PoE – it is powered up by a network command received from the control unit (hearable by the „click“)

update: after having tried in „real life“ connecting the RF unit through a VLAN across a complex network infrastucture I found out that there must not be any other network traffic in the VLAN (no RTSP, other broadcasts, etc.) – otherwise the controller unit won’t even connect to the RF unit.

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Datum: Donnerstag, 13. Juli 2023 16:32