I am wondering why the supply current is listed at only 150mA, since this is a 10W PA operating on 28V supply and ~50% effciency i would expect something closer to 650mA for supply current requirement.
The supply current of 150 mA is the quiescent current, i.e. the DC bias current under the condition of no RF input drive. Under small-signal RF drive that current should remain very close to 150 mA. The drain current required a higher RF input drive levels, however, will increase in response to the increasing RF input drive. That effect is what is commonly called, "self-biasing". The drain current vs. RF Pin response can be seen on figures 28, 30, and 31 of the data sheet:
As shown on those figures, when driven to saturation the drain current current can exceed 1000 mA. Those figures also include the Pout, Gain, and PAE vs. RF Pin.
Please note that the part you have asked about, the HMC1114LP5DE, is in the Last Time Buy phase of the product life-cycle. The part is being replaced by the HMC1114PM5E, product page linked below:
Let me know if more info is needed.