I have looked around and there is no definite answers regarding this.
You are right about that. You will not be able to find some official document with the list of compatible parts.
I don’t know where you got this info about “upgrade with another one” and try to ask this person why do you have this problem now.
Fact is that you cannot use any card and compatibility is very important. Equium A200 is old notebook model and I don’t think you can use some newer cards with new standards.
Your Equium has originally Realtek 802.11g (RTL8187B) that uses, I think two antenna cables and you want to use standard n with three antenna cables. Am I right about that? How have you connected antenna cables?
Anyway, I recommend you to use the same WLAN card or, if you want to use card with better and faster data transfer rate buy small micro WLAN USB stick.