Skip 20F001N in RTL8019AS

Um, no... I seriously doubt this would work. There are several inductors and a transformer in the block for filtering and isolation. And depending on the controller, the transformer windings are also not

1:1.

Why not just get an RJ45 jack with internal magnetics? They're only slightly larger than a standard RJ-45 jack, and not expensive at all. Then only a few resistors and caps are needed on the signals between the RTL8019AS and the RJ-45.

Bothhand and Delta are very popular, but there are many companies in this space. Here are a few:

Digi-Key sells Tyco and 1-2 others, though they're cleverly hidden amongst the other RJ-45 jacks and critical specs are missing (i.e., read the manufacturer specs before looking on Digi-Key for pricing).

See also

for proto boards and loose parts. Ask if you don't see the part listed - Ed's pretty good about selling loose parts.

I have tried connecting it directly to PC and XP could detects the existence and shows the connecion icon on the tray. But I am not sure whether this represents the data sent/received is ok. But anyway, your information is very helpful. Thank you very much.

OK, now I use a T-filter which is from an old broad. The data can be received now. So I confirm that direct connection is not ok.