MMIC

The MMIC used in the receiver is a 1651. Almost any MMIC could be used here. The 1651 is a surplus part that can be found at some electronic surplus stores.

The MAR-xx series MMIC's have 12 Volts delivered through the input lead, with the two pins in the middle of the device used for grounds. If you substitute, be sure to double check the 12 Volts wiring on the device datasheet.

The maximum output of the MMIC is 400 miliwatts, which is the maximum input that the NE602 can handle. This means it is very unlikely that the NE602 product detector will be overloaded by the output of the MMIC.

Check out the article "Monolithic Microwave Integrated Circuits,", QST, February 1987, Page 23. Subtitle was "Part 1: Wait! Even if you're not interested in microwaves, you can still use these low-level gain blocks in your next RF project. They work from dc to nearly daylight!"

The author described how to use them at HF. Very, very easy to build.