The General Radio 1840A measures audio-frequency power into any desired load. Its important uses include the measurement of:
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 swithches connect eight identical primary winding and six seconday taps in various combinations toprovide a total of 48 different primary impedances.
The maximim power rating can be extended for anygiven impedance with the use of a simple T-network attenuator,design date for which are supplied with the instrument.
Power:0.1mW to 20W, 40Hz to 20kHz, Below 40Hz, maxrating is reduced by up to 50% (at 25Hz), depending on impedance selected. See curve. Auxiliary dB scale reads from -15 to +43 dB re 1mW
Impedance:0.6Ω to 32kΩ in two ranges; yielding 48 individual impedances spaced approximately 
apart
Accuracy
Power:At 1kHz, ±0.3dB
50Hz to 6kHz,±0.5dB
30Hz to 10kHz,±1dB
at 20Hz,-1.5dB max,-1dB avg;
at 10kHz, -5dB max,±1.5dB avg.
Impedance: At 1kHz,±6% max,-0.5% avg;
70Hz to 2.5kHz,±7% above 10kΩ;
70Hz to 5kHz, ±7% below 10kΩ;
at 20Hz,-15% max, -8% avg;
at 20kHz, ±50% max, ±12% avg.
Waveform Error:Meter will indicate true rms with as much as 20% second and third harmonics present in the input signal.
GENERAL
Mounting:Convertible-Bench Cabinet. Adaptors for rack mounting available.
Dimensions: 305 x 105 x205 mm
Weight:Net, 4.9kg; shipping,8kg
