On Sun, 13 Sep 2009 05:21:08 -0500, Chuck Forsberg WA7KGX N2469R
wrote:

The B version has a piece of mast below the main part of the
antenna. Is there much difference in performance between
the arx2b and the original arx2?


It's been a long time, but I think the non-b version was criticized
for having a lot of RF on the feedline. That would distort the
radiation pattern somewhat. The b version corrected that.