PMI Model No. PIA-12D8G-CD-1, Phase Locked, Dielectric Resonator Oscillator has Internal Reference having an output frequency of 12.8 GHz and provides a minimum output of +13 dBm with all spurs held to -80 dBc, harmonics held to -25 dBc. Frequency stability is ±3 ppm with an internal reference of 100 MHz.  Unit measures 2.25" x 2.25" x 0.62" and has SMA Female connectors. https://www.pmi-rf.com/product-details/pia-12d8g-cd-1