The device in the block diagram should work as follows:
- The heart of the circuit is a VCO with switchable bands for AM and FM. It can be swept using a generator ramp, which is triggered by a blanking pulse from the oscilloscope.
- There is also a circuit to display the desired frequency on the HF envelope. I forgot to draw that a ramp signal enters this circuit, which is gradually compared with fixed frequencies. If the current ramp is at the same level as the fixed frequency, the circuit will output a pulse which will appear as a brighter dot on the curve. In this way, for example, 3 points (frequencies) on the curve could be set, according to which the curve would be tuned. The circuit can also be expanded to display multiple points.
- There would be two buffers at the output of the HF generator, one for the HF signal output, the other for the counter.