Hey!
Yes you are right.
I made a typo, it should be 50 Ohm's.
Sorry, I will edit my old post...
We bought them at a local WiFi specialized distributor (a suggestion would not be helpful for you, because I'm located in Austria).
But you can find them also at amazon, or some electronic dealers.
Basically, you have to terminate all unused antenna connectors.
If you will not terminate them, the AP can get demaged (If somebody disagrees, please correct me).
See the attached AP-270 Installation guide.
On page 6 you will find a connector description.
We terminated the 5G2 and 2G2 connectors.
But it is not clearly documented if you have to connect the V to a specific antenna port.
My personal opinion is, that it doesn't matter.
Because if it would be important, than there would be a note in the installation guides of the AP or antennas.
But maybe, a aruba employee should confirm that - or you contact TAC.