Recently I've got a 5343A counter. If works good, except that in the range of about 10-26GHz it sometimes shows a frequency with approx +300 to +350MHz (positive) error. The symptom is the same as the original author had. Many times it solves the issue
and shows the correct frequency, but only after a few seconds.
?
Looks like it can not determine/decide on the factor correctly. Any ideas?