This paper presents the analysis and measurements of the effects of heterogeneous cross-coupling time delays on synchronized states in a network of mutually coupled oscillators. In a network of three mutually coupled phase-locked loops, operating at 24 GHz in a chain topology, the phase relations and frequency of the synchronized state are quantified. The measurements show that such delay heterogeneity changes the properties of self-organized synchronized states. Specifically, it reduces the range of frequencies over which self-organized synchronous states form. It is observed that the frequency of the self-organized synchronized state that would form over a sub-network of two oscillators alone, lies within this range. The experimental observations presented here reveal new insights into the effects of heterogeneity on the dynamics of self-organization in mutually delay-coupled oscillators and the implications for the properties of synchronized states.