Archer TX50E external antenna available for purchase?

Hello   @GLHF1981 

The TX50E network adapter antennas are attached to the adapter itself and does not need a base. (hard to ensure compatibility with the base) 
As you already got the TX50E , you could test the performance of the TX50E on your computer, if the Wi-Fi signal it received is weak or the router is very far from the adapter, you could consider getting the model TX3000E which has a magnetic base to put antennas outside to receive better Wi-Fi signal.

Hope this helps.