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The Hewlett-Packard 334A Distortion Analyzer is a solid state instrument for measuring distortion of sinusoidal signals. In addition the 334A has a high impedance detector which operates from 550 kHz to greater than 65 MHz and provides the capability of monitoring the distortion of the amplitude modulation on an RF carrier. Noise levels as low as 25 microvolts can be measured.
An frequency distortion analyzer is basically a precise AC volt-meter with very flat frequency response from 10Hz to 1MHz ( +- 0.05 db). Distortion measurement takes two voltage readings where the first reading includes fundamental and harmonics, the second reading includes only the harmonics. The percentage distortion is the ratio of these two readings. (2nd reading/1st reading). If the 1st reading being set to 1 unit, the 2nd reading can give the answer directly.
The HP334A solid state distortion analyzers were probably the most popular harmonic distortion analyzers ever made. This machine can measure frequencies 5Hz to 600KHz and THD (Total Harmonic Distortion) down to 0.1% full scale. It's very useful for audio amplifiers, ultrasonics, and tube gear. A summary of the HP 334A key features are:
Voltmeter range and accuracy
300 mV range +/- 2%, 30 Hz to 300 kHz +/- 5%, 20 Hz to 500 kHz
1 mV to 30 V range+/- 2%, 10 Hz to 1 MHz +/- 5%, 5 Hz to 3 MHz
100 to 300 V range +/- 2%, 10 Hz to 300 kHz +/- 5%, 5 Hz to 500 kHz
High pass filter (Hewlett-Packard Models 333A and 334A)
3 dB down at 400 Hz; 60 Hz rejection >40 dB
Low pass filter (Hewlett-Packard Model 334A option 002)
3 dB down at 30 kHz; -23.6 dB at 60 kHz
Residual noise
<25 mV rms with input shielded and terminated with 600 Ohm
Set level sensitivity
0.3 rms for 100% set level (up to 300 V may be attenuated to set level reference)
Frequency calibration accuracy
+/- 5%, 5 Hz to 300 kHz +/- 10%, 300 to 600 kHz
Second harmonic range and accuracy
5 to 20 Hz, >+1 dB
20 Hz to 20 kHz >+/- 0.6 dB
20 to 100 kHz.-1 dB
100 to 300 kHz >-2 dB
300 to 600 kHz >-3 dB
Residual distortion
>-70 dB, 5 Hz to 200 kHz
>-64 dB, 200 to 600 kHz
Automatic null (Hewlett-Packard Models 333A and 334A)
0 to +3 dB from manual null (5 to 100 Hz)
0 to +1.5 dB from manual null (100 Hz to 600 kHz)
Fundamental frequency rejection
>80 dB