874-GA
The General Radio 874-GA Adjustable Attenuator was introduced in Catalog M (1951) and remained available through Catalog Q (1961).
The Type 874-GA is a mutual-inductance (waveguide-below-cutoff) type attenuator. A micrometer-type barrel adjusts the distance between a pick-up loop attached to a three-foot coaxial cable and the short section of the input coaxial line. Both the barrel and adjusting sleeve are calibrated in decibels, one turn produces a change of 20 dB for a total or 120 dB of attenuation. Used with other coaxial elements the such as the 874-VI Voltmeter Indicator or the 874-VR Voltmeter Rectifier, the 874-GA can be used to attenuate and monitor signal generators and oscillators. The attenuator can also be used to measure the attenuation of a network by the substitution method.
Specifications
- Calibrated Range: 120 dB
- Insertion Loss:
- At beginning of calibrated range: Approximately inversely proportional to frequency up to 1 GHz; approximately 20 dB at 1 GHz with tuned input; approximately 33 dB with input line terminated in 50 Ω
- Outside of calibrated range: Approximately inversely proportional to frequency; approximately 18 dB at 1 GHz
- Accuracy of Attenuation: ±0.5 dB when corrected
- Frequency Range: 100 MHz to 3 GHz
- Waveguide Mode: TE1,1; cutoff frequency 12.3 GHz
