[Richard]

You're welcome, the same hook up and settings can be used to check Phono3 RIAA accuracy by sweeping sine frequency from the sig gen whilst watching for any deviation from flat on the scope. It should just show roll-offs at each end of a flat response. Be careful to use low capacitance coax to hook up, such as good hifi i/cs, so as not to roll off the highs inadvertently.

The inverse RIAA filter can also be checked for accuracy against the Hagerman literature ref 1Kz sine but it should be fine if carefully built.