Dip meters are no more manufactured (and old ones are no more calibrated). These devices were thought to be very useful to a large game of ham radio and electrical engineers.
Usually, when a device disappears, this is because there are cheaper or more powerful devices on the market. Yet, it is not obvious what has actually replaced dip meters.
My question is: What is the modern replacement for dip meters?
or, to put in a more practical way, when you have to measure the resonance frequency of a circuit (without connecting it physically to a measurement device), what do you do?