874-MR

The General Radio 874-MR Mixer Rectifier was introduced in Catalog M (1951) and remained available through Catalog 1973.

The Type 874-MR is a device used to mix two signals, the input signal and a local oscillator, to produce an intermediate frequency. The range of both input and local oscillator is 50 to 5000 MHz, and the heterodyne produced intermediate frequency is up to 30 MHz. This enables UHF signals to be monitored conveniently by radio receiver, wide-band amplifier or null detectors operating at this IF frequency. The output signal from the 874-MR passes through a rectifier, then a low-pass filter. The maximum input from the local oscillator must be kept below 2 V to prevent damage to the 1N21 rectifier.

Specifications

• Operating Frequency: 50 to 3000 MHz
• Maximum Crystal Current: 5 mA
• Maximum Input from Local Oscillator: 2 V
• Cut-Off Frequency of Output Fitter: 40 MHz

Links

• Experimenter May 1950 describing Type 874-MR
• 1N21B Microwave Diode Data

Photos

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  1N21B Diode

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  Schematic