The TF2330 is a narrow band tuned voltmeter covering the range 3 μV to 300 V. It can be tuned to any frequency between 20 Hz and 50 kHz in a single continuous band, using the unusual dial (pictured) that has a spiral scale with a moving marker behind it. The bandwidth is 7 Hz; an AFC facility is available to lock the instrument to the frequency of the input signal.

Measurements of harmonic distortion down to -75 dBc can be made directly. An optional tunable rejection filter (TF2334) was available to remove the fundamental frequency thus enabling harmonic distortion measurements as low as a few parts per million.

A later version, the TF2330A, provided an extended frequency coverage up to 76 kHz.

TF2330 functional block diagram