  The coax based MO distribution system in the ALS is going to be replaced by a
modernized, lower phase noise and more interference tolerant version, ready to
support ALS-U operation. System aspects are shown and several commercial analog
and digital optical transceiver modules are compared for their suitability in
this application. Furthermore, recent phase noise optimizing efforts in the ALS
RF system are discussed and several prototypes for a custom built, low phase
noise, frequency adjustable master oscillator around 500 MHz are shown.
