You can make a minor add-on to the MFJ 260C 300 Dry Dummy Load that extends the utility of this box. A 60 db attenuation pad output is added. This tap is great for a scope connection. Nice.
Figure 1 shows how I have added a circular mount BNC receptacle to the box. I show in an internal close up, Figure 2, how I have added a 1:1000 divider from the usual SO-239 output to the BNC. I used 56 and 56K ohm parts. (Because I had them).
Figure 3 shows the modified box in action looking at a SSB signal.