|Year: 1941||Type: Service- or Lab Equipment|
|Valves / Tubes||21: 6SJ7 6SJ7 6SJ7 6SJ7 6SJ7 6SJ7 6SJ7 6SJ7 6SJ7 6SJ7 6H6 6SN7 6SJ7 6SJ7 6SJ7 6SJ7 6J7 6F6 6SQ7 6L6GA 5U4 0A2|
|Wave bands||Wave Bands given in the notes.|
|Power type and voltage||Alternating Current supply (AC) / 115 Volt|
|Loudspeaker||- - No sound reproduction output.|
|from Radiomuseum.org||Model: Harmonic Wave Analyzer 300A - Hewlett-Packard, HP; Palo Alto|
|Shape||Tablemodel, high profile (upright - NOT Cathedral nor decorative).|
Info of HPs page:
see also -hp- Distortion Measuring Equipment
|Source of data||-- Collector info (Sammler)|
Model page created by Ernst Erb. See "Data change" for further contributors.
All listed radios etc. from Hewlett-Packard, (HP); Palo Alto, CA
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Harmonic Wave Analyzer
USE IT TO ANALYZE:
VARIABLE SELECTIVITY PROVIDES RAPID, ACCURATE WAVE ANALYSIS
This -hp- Model 300A Harmonic Wave Analyzer is a selective voltmeter designed to measure the individual components of complex waves. The selectivity can be varied by means of a unique selective amplifier. Where the harmonics are close together the high selectivity easily separates the wave components. Yet, where the components are spaced far apart, the selectivity may be widened to increase the speed of operation without sacrificing essential accuracy. This feature is also valuable where it is necessary to measure distortion of waves containing a small amount of frequency modulation, such as in sound tracks, and may be used conveniently to integrate a small portion of the audio spectrum in noise measurements and the like. Maximum selectivity is sufficient to separate harmonic components spaced 30 cycles apart. see figure 1.
The -hp- Model 300A Harmonic Wave Analyzer covers the audio spectrum from 30 cps to 16,000 cps. The wide voltage range covers the values encountered in nearly every application. Full scale voltmeter readings may be obtained with inputs of .001 to 500 volts so that the instrument may be used with equal success with low output transducers and high power modulating amplifiers. Other features which make it unexcelled for both laboratory and production testing are the linear meter scales fully protected against overloads, and the built-in calibrating system to standardize voltage measurements.
The circuit of the Model 300A consists of a variable local oscillator, a balanced modulator, a selective amplifier, and an indicating meter. The variable local oscillator modulates the unknown frequency to produce a constant difference frequency. This difference frequency is applied to the selective amplifier, the output of which is then proportional to the magnitude of the unknown voltage. A meter in the output of the selective amplifier indicates the magnitude of the voltage.
The local oscillator is of the resistance-tuned type, providing a very stable, accurate voltage. A balanced modulator is used to eliminate the local oscillator frequency and to keep cross-modulation products very low. The selective amplifier consists of four tuned circuits in which the effective Q is controlled by positive feedback. Negative feedback is also used to stabilize the amplifier.
This amplifier has the unique characteristic that its selectivity may be varied over a wide range without appreciably affecting the gain of the amplifier.