SOLUTION

• A heterodyne frequency meter is an oscillator in which the tuning control is calibrated in terms of frequency.
• The oscillator used is stable and tuneable and depends upon the frequency range to be covered.
• It is desirable that the oscillator has a low-temperature coefficient of frequency, and that its frequency be insensitive to changes in the supply voltage.
• Good mechanical construction is also desirable.
• The oscillator of the heterodyne frequency meter must be isolated by a suitable buffer circuit arrangement so that its frequency is not affected by either the energy or the impedance of the circuits into which the frequency meter is connected when making measurements.
• When a heterodyne frequency meter is to be used for interpolation purposes, it is desirable that the frequency be linearly proportional to the angle of rotation of the tuning dial to a high degree of precision.

The accuracy of the frequency indicated by a heterodyne frequency meter is ordinarily greater than the accuracy of the corresponding lumped-circuit wavemeter. This is because an oscillator generates a definite frequency for any particular setting of its resonant tank circuit.

Applications:-

Heterodyne frequency meters are employed for such purposes

• Producing known frequencies
• Measuring an unknown frequency by comparison with the controllable an unknown frequency of the heterodyne frequency meter
• For interpolation between known fixed frequencies.
• Superheterodyne circuit found in almost all radio and television receivers, it is used in radio transmitters, modems, satellite communications and set-top boxes, radar, radio telescopes, telemetry systems, cell phones, cable television converter boxes and headends, microwave relays, metal detectors, atomic clocks, and military electronic countermeasures (jamming) systems.