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    Local Oscillator and Phaselock System

    The local oscillator system for the SZA and the heterogenous array CARMA are being built at the University of Chicago. This page focuses on the test set up for the SZA double down frequency conversion. The image below shows the test set up that includes a YIG oscillator and a bias tuned Gunn oscillator and their respective phase locking boards. Graduate student Brian Epley assembled the prototype YIG board that controls the YIG oscillator. Michael Loh, another graduate student, has been updating and writing software for the boards. He is also debugging and testing the boards. The layout for all the boards built for the SZA was designed by staff engineer, Frank DiDonna.

    Test setup for SZA double down conversion. Click on image for larger version, opens n another window.
    Test setup for the SZA double down conversion. The commercial XL Microwave Phaselock loop (PLL) board (green board on left) was used to phase lock the 90 GHz Bias Tuned GUNN oscillator. The prototype SZA YIG PLL board (center board, green) was used to phase lock the YIG oscillator operating at about 10 GHz. The Dielectric Resonating Oscillator (17.5 GHz, at center with clamp) is internally phase locked. Click on image for larger version (opens in another window).

    The XL Microwave PLL board will be replaced by the Bias Tuned GUNN PLL board. The main difference between the boards is that the Gunn board can be controlled by software. A picture of the Bias Tuned GUNN PLL board is below. A larger version, which opens in another window, is available upon clicking the image.

    Bias Tuned GUNN PLL board. Click on image for larger version

    Center for Cosmological Physics | U of Chicago Astronomy Department | University of Chicago