Hi,
Some time ago I picked up this 60’s METRIC 742C for cheap at a yard sale (before the confinement).
It’s a very neat piece of equipment. However, it was missing the AC probe. So today I finally took the time to build one
According to the schematic. It’s using a 6AL5 double diode detector tube. Fortunately I had a few lying around.
It’s not pretty, but it works great.