I just got what appears to be a new test set AN/URM-90 containing an RCL bridge ZM-30/U. The instrument looks a lot like a GR-650, but is made by International Instruments. It has a 12AX7, a 12AT7, a 6U5, and what looks like a full-wave selenium bridge-rectifier. The tag on the outside says it doesn't work. Anyone know anything about this instrument? Ken Gordon W7EKB