Abstract: An automatic modulation leveling circuit gain controlled by the tuning voltage level into the voltage controlled oscillator of an FM frequency synthesizer providing a normalized modulation gain. The automatic modulation leveling circuit is used in a basic 10 KHz tuning increment direct synthesizer with a skewed frequency standard deriving four intermediate tuning steps of 2.5 KHz each. The leveling circuit includes an amplifier with gain to both DC and AC set by the ratio of a feedback resistor to the value of an input resistor that is a photo resistor subject to resistance change with light variance of a light emitting diode as driven by a second amplifier in the circuit.