874-MR

The General Radio 874-MR Mixer Rectifier was introduced in Catalog M (1951) and remained available through Catalog 1973, after which only the 874-MRL version with locking connectors remained available.

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 40 to 5000 MHz, and the intermediate frequency range is up to 30 MHz.

Tge 874-MR enables UHF signals to be monitored conveniently by radio receivers, wide-band amplifiers or null detectors operating at the IF frequency.

The output signal from the 874-MR passes through a 1N21 diode followed by a low-pass pi filter.

Maximum input from the local oscillator must be kept below 2 V to prevent damage to the 1N21 rectifier.

Specifications

• Operating Frequency: 40 to 5000 MHz
• Maximum Crystal Current: 5 mA
• Maximum Input from Local Oscillator: 2 V
• Cut-Off Frequency of Output Filter: 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