USB WiFi adapter doesn't work with Wheezy (but does work with Ubuntu)

[dclinton <dclinton@hcn-inc.com>]

Hi,
I've been having all kinds of trouble finding a dual band USB WiFi adapter that will work with Debian Wheezy and I hope someone here can help. Our best (and pretty much last) hope is the TP-Link N900 TL-WDN4200. Using it successfully on Ubuntu 13.10, lsusb identifies the chipset as

RT3573 Wireless Adapter (Ralink)

and iwconfig assigns it:

ra0 Ralink STA 

lsmod reports that the adapter is using the rt5572sta driver.

However, when I insert it into a Debian machine - whether its my Intel Galileo running a full Debian image or my own Ubuntu PC running a Debian live USB session - I'm having no luck. Dmesg identifies it with only:

usb 1-1: new high-speed USB device number 3 using ehci-pci

lsusb correctly sees it as:

ID 148f:3573 Ralink Technology, Corp. RT3573 Wireless Adapter

but that's where the fun stops. Here's iwconfig:

lo        no wireless extensions.
eth0      no wireless extensions.

iw list gives me this rather cryptic message:

nl80211 not found

and the only remotely relevant reference in lsmod is

ehci-pci

I've installed firmware-ralink and searched for an appropriate rt5572sta package. I found an rpm for OpenSuse here:

http://www.filewatcher.com/m/rt5572sta-common-2.6.1.3-6.3.noarch.rpm.15942-0.html

converted it to deb using alien and installed it, but there was no change. (It was a long shot in any case.)
There is supposed to be a driver here:

http://www.mediatek.com/en/downloads/

but there's something wrong with their page and it doesn't actually download (I've sent them an email for help).
Does anyone have any ideas?
Thanks so much!