The tubes in my Chippewa don't appear to match. One is clearly labeled "Eimac 4-400A" but the other tube has no markings on it and the plate is shaped a bit different. Any ideas? Here is a pic: http://n1ese.qrpradio.com/AM/4-400A.jpg -- JT Croteau, N1ESE - Manchester, NH (FN42gx)