Drake W-4 meter going backwards
 

I think I have found the problem. With a very good dummy load the meter
would go backwards, but with some that show a swr of about 1.7 the meter
acts normally. I pulled the book on the meter and found in the calibration
procedure about adjusting a trimmer capacitor inside the unit. That took
care of the problem. I had not done a W4 before, but remmeber that trimmer
capacitor from a Heathkit meter I built about 40 years ago.

I have verified it with another wattmeter and they agree within reason. I
don't think that trimmer was out far enough to effect the calibration very
much if any that is noticable.