I built this one last night. I hooked my AF generator to it with the output at minimum. I could hear the tone. I put my meter across the input and it was to low to read. When I adjusted the input to 10uv (the first digit on my meter) it was loud enough.
As I was connecting the leads I could hear some buzzing. I put my scope on C2 and when I hooked a lead wire to the input I got about 3 volts pk-pk at 1.7 mhz. The little amp is so strong I will need to filter and/or shield it.