This was an exceptional find. I will describe it later. I noticed it's from the city of Annecy, same as were the Metrix U61B comes from. That relation is perhaps no coincidence. This tester looks a bit like a Taylor 45C. It has one defective selector switch, but that looks easy to repair. Just need to have time. So I can not select every tube, but almost any. This little pearl is based on the circuitry of the 45C, but it has more and better options, also it had the selectors for any random tube, same as the AVO's have. All together this is a mix of AVO Mk1, Taylor 45C, and the designer saved absolutely not on nice options. It has for instance the professional leakage test method, same as the AVO's have. This means a real ohms measurement, but with a high voltage as bias. These Frence designers were aware, sometimes the one, sometimes the other method is better. Heater voltage very interestingly done, with a coarse and a fine adjustment. Well, I have not really looked at it in full detail, but I will probably restore it completely. . Some incandescent lamps are used as a fuse, same as Hickok does. Fact is, the tester works, and is precise. It can do many of the European B4B5 socket tubes like PX4, PX 25, etc. Easy to handle and a nice design.
There is the original French manual, and a very well made translation in Dutch. This Dutch translation you can enter in the Google translator and it nicely gives English instructions.
As a pre-test it has a way to test the cathode all alone, so without any function of the rest of the tube. They write in French, this indicated a troublesome tube, but for the rest the transconductance should be tested to judge the tube.
It is larger as it looks on the picture, and quite heavy, the metal handles make sense.