Dave, the ( stock ) RU has to be more broad than the ARC-2, doesn't it? The ARC-2 has 4 tuned IF circuits at 1 - 1.5 MHz variable. The RU on 80 meters has 3 tuned circuits for 3.5 - 4 MHz. Notice I did say "stock". I understand your kink for bringing up the RU selectivity helps a great deal. -Hue Miller