Hello Alfredo,
Yes, there is a 25 ohm resistor inside the connector. After that all is 50 ohm. The nicest thing is to find a N connector, like on the 2712, and connect that with semi-rigid to the attenuator.
From then you can do more, like changing to the 2712 software. Try to find a 300Hz filter, etc.
I send you a private mail about this several days ago, but perhaps you missed that.
Jaap
