The ICF-EX5 is basically a Japanese-market upgrade for the ICF-S5(W) series, adding double conversion and a synch detector (but not an improved 455 kHz IF filter, or improved loopstick design).
The loopstick in the ICF-EX5 is indeed more isolated away from the main circuit board, however, which may account for your discovery of slightly better nulling ability than that of the ICF-S5W. All of the modified portables here have gained a significant increase in nulling ability, when a loopstick is mounted outside and above the radio's cabinet. For example, the new Slider E100's can null out locals and receive noontime daytime DX stations 10 kHz away, at distances of 150-200 miles during the enhanced December conditions.
The tilted loopstick in the ICF-S5(W) series can improve nulling ability in some cases, but Sony's placement of the loopstick near the middle of the cabinet would tend to minimize this advantage. My own impression is that Sony chose this loopstick position as a matter of convenience, to avoid having the 4 main loopstick coil wires (and the other 4 from the external antenna connector jack) interfere with the dial string system (having the red and green LED's moving across the top of the analog dial). When I designed the Slider loopstick for the ICF-S5W (which ultimately was a DUD), I needed to thread the 4 loopstick Litz wires through an empty screw hole in the center of the back cabinet, in order to avoid snarling the dial string system. Sony probably placed the stock loopstick in the middle of the cabinet, for the same reason.
In a message dated 12/26/2008 1:03:40 P.M. Pacific Standard Time, lrdheat@... writes: