Hi, I would like to take a note about RB493G USB, the spec says “USB 1, external power required”.
Does it mean I have to use some kind of USB-hub with external power to connect 3G modem?
Now I have RB751U and 3G modem plugged there and works.
Why do RB433GL and RB435G have “USB 1” and “USB 2” in the spec without any additional notes? Do they have USB port with power?
May I ask why RB493G USB port is differ?
Thank you guys, you are quite useful 
Even if the question is stupid it would be nice to point that also.
The RB493G does NOT provide the 5V to the USB port, you need to use some of this to “power” your 3G modem.
I see.
I also finally found the topic with similar discussion.. http://forum.mikrotik.com/t/routerboard-usb-port-not-active/45888/9
Can anyone share own experience? Do people use powered USB hub with external power adapter? Solder somehow?
My goal was to replace RB751U+RB750GL with single device and power up the 3G modem. Maybe some other suggestions?
From my testing, the RB751U does not provide usb power so I’m wondering how the 3G modem would have worked?
Now on the other hand, the RB751G I have does provide usb power.
Are you sure? Cause I have Huawei E367 plugged in and it works fine.
According to the spec here http://routerboard.com/RB751U-2HnD it has powered USB port.
I only tested two of them, but neither of them had a powered usb port. I don’t see on the spec sheet where it says the usb port is powered? If it does, that’s great, because it would save me having to use those little injectors.
When I get time, I’ll try testing a different one just to be sure.
We had a 493g and a powered USB hub and it still wasn’t enough to get the 3G modem recognised. Had to follow the mod suggested in this thread. Has been working fine since.
http://forum.mikrotik.com/t/routerboard-usb-port-not-active/45888/12
What 3G modem you used? What USB hub model? What voltage the hub produced?
Just wanted to follow up. I got around to testing a couple of other RB751U’s and they do indeed have a powered usb port. Which is great news to me.
I’m wondering if the other ones that I had were a different hardware revision or if they had a defect.