Genrad 1840-A

• *Power output of oscillators, amplifiers, preamplifiers, transformers, transducers, and low-frequency lines.
• *Output impedance, by adjustment of the load to yield maximum power indication.
• *Frequency-response characteristics of amplifiers, transformers, and other audio-frequency devices.

This instrument is basically a multi-tapped audio-frequency transformer with a fixed secondary load. Its two front-panel switches connect eight identical primary windings and six secondary taps in various combinations to provide a total of 48 different primary impedances.

The maximum power rating can be extended for any given impedance with the use of simple T-network attenuator, design data for which are supplied with the instrument.

Power Range:
0.1 mW to 20 watts in five ranges, 40 Hz to 20 kHz; maximum rating is reduced by up to 50% (at 25 Hz), depending on impedance selected.

An auxiliary dB scale on the meter reads from -15 to +3 dB, referred to 1 mW.

Impedance Range:
0.6 Ω to 32 kΩ in two ranges; yielding 48 individual impedances spaced approximately 2 apart.

Accuracy
Impedance:
at 1 kHz, ±6% max, -0.5% avg;
70 Hz to 2.5 kHz, ±7% above 10 kW;
70 Hz to 5 kHz, ±7% below 10 kW;
at 20 Hz, -15% max, -8% avg;
at 20 kHz, ±50% max, ±12% avg
When impedance is specified, accuracy applies at full-scale on all ranges and impedances at 1 kHz;
when frequency ranges are specified, accuracy is at full-scale at ranges ≥20 mW at the specified impedances.
When a frequency limit is specified, accuracy is at full-scale at all impedances

Power:
at 1 kHz, ±0.3 dB;
50 Hz to 6 kHz, ±0.5 dB;
30 Hz to 10 kHz, ±1 dB;
at 20 Hz, -1.5 dB max, -1 dB avg;
at 20 kHz, -5 dB max, ±1.5 dB avg.

Waveform Error:
Meter will indicate true rms with as much as 20% second and third harmonics present in the input signal.