Building a simplex repeater

Kenneth Finnegan writes, “In this installment of the “How to Build a Repeater” series, I explain the concept of a simplex repeater and how to assemble one out of an Argent Data ADS-SR1 and a Motorola Maxtrac. Thanks again to Argent Data for providing me with an ADS-SR1 to play with; it’s a fun little controller.”

More info at┬áKenneth’s blog.

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  1. He has the green Engineer’s paper on the bench upside-down. Also, I seem to remember that if you have a spectrum analyzer (a cheap RTL-SDR dongle will probably work) you can measure/set the modulation index by looking at the ratio of the carrier to the first side-band “shoulder” with a known test tone audio input. The ratio is a Bessel function that is dependent on the test tone parameters and the modulation index. In-fact at some pont the test tone will 100% eliminate the carrier, this is called a “Bessel drop-out”.

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