Tom,
Since the set is working well on 1 range it seems that front end alignment issues are the likely problem. It is also possible that the tube used for the heterodyne oscillator is weak and is not producing sufficient injection voltage except with a very active crystal so you might want to check that tube (V-3, 12BE6). However, are you using the same cables for the injection and antenna lines that were used by the previous owner? If he used low capacitance (or higher capacitance) lines when they were aligned then using different ones will affect the operation so check this before you go through the alignment process and maybe all you need to do is interchange some of your set of cables. Otherwise, the 4 line alignment is straightforward. Instead of using the loading circuits in the Drake manual, I do the alignment with the R4/T4 hooked together with the cables they will be used with and this has worked well for all of my 4 lines (I have the 4, A, B, and C lines). Do make sure that the slugs are at the proper height when you start the process and that the preselector tune knob is also indexed correctly. As I recall, one set of trimmers is hot so be sure and use an insulated alignment tool and also be aware that the S meter terminals are at B+ and you will get fairly close to them during part of the alignment. Enjoy your new B line! 73, Rodger WQ9E Tom Weigel wrote: Hello: With the exception of 40M, where the set performs very well, my R-4B has extremely weak or nonexistent PreSelector peaks and extremely weak receive. This happens whether operating standalone or in transceive with my T-4XB. The previous owner installed a small breadboard circuit described on an accompanying hand-drawn schematic as "Improved Product Detector Using MC 1496L," from the December, 1977 issue of Ham Radio. I think that this mod was originally meant for the R-4C, but I really don't know. I also suspect that the previous owner could have only used these Twins on 40M. Again, I am guessing! I have gone through and cleaned all of the bandswitches with Q-Tip and DeOxit, lifting off some tarnish from the circular switch surfaces. Is a complete realignment session in order for my R-4B? Bad crystals? Anyone else have additional ideas? Thanks in advance, Tom, ABØJ Minneapolis, MN
