Well since it seems off about 50Khz as when I dial 50.95 the test set shows 51.0001 I suspect the A10(A40 for PRC-77)50Khz interval oscillator may be suspect. My prc-25 has an A40 instead of an A10 so at some point it was replaced. I'm wondering now if the A40 and the knob connection are off one click? Mark K1HF