Many wireless devices have requirements that emphasize low size, weight and power for increased functionality and extended lifetimes. The additional complexity of these devices mandates the need to dynamically verify that all sub-system functions are fully operational. These tests can only be performed internal to the unit, and a circuit that could be utilized to meet this demand should be constructed to be as simple as possible. This paper presents both a novel set of equations to represent a compact comb generator circuit using a step recovery diode as well as unique sequential measurements of a prototype to provide greater insight into the design. The analyzed circuit requires no bias voltage, and effectively produces harmonics up to 2 GHz with a 2 MHz input signal, which is sufficient for adding built-in-test capability to most wireless devices.