The ISR2800D is the first in a series of radiation-hardened, high-reliability power supplies to be offered by MSK. The ISR2800D is specifically optimized to drive transmit/receive (T/R) modules in Phased Array Antennas (PAA), but as a result of its high-performance capabilities and numerous built-in features, it is ideal for many other applications. The ISR2800D utilizes two DC-DC converters to optimize power conversion efficiency and facilitate voltage sequencing necessary to protect T/R modules during power-up and power-down. A small flyback converter, referenced to input return and switching at 200kHz, is used to provide electrical input-output isolation, generate nominal +10VDC bias voltages for the input and output control circuits of the power supply, and generate a nominal -5VDC negative output voltage for the T/R modules. The negative output voltage for the T/R modules is cross-regulated via a tap on the flyback transformer and referenced to output return. A low drop-out (LDO) linear regulator is then used to further post-regulate this output voltage to ensure tight regulation and low ripple, typically less than 5mVp-p. A single transistor forward converter, referenced to output return and switching at 100kHz, provides the positive adjustable output voltage. They are enclosed in a hermetic Silicon Aluminum (SiAl) package and weigh less than TBD grams. The package utilizes rugged ceramic feed-through Glid-Cop pins and is sealed using parallel seam welding.