Jim, This happened to my R-4B a couple years ago and turned out to be C192, a 1000 uF capacitor in the supply for the calibrator and has been known to fail frequently. Yours might have the same component if they kept the calibrator the same in the R-4C. 73, Chris, W2PA Jim wrote: >I have a dead R-4C calibrator. Any one knows what typically fails? >