April Instrument was founded in 1989 to bring portability to the microwave signal generator field. Changes in microwave components allowed this to happen including the advent of MMIC's ( monolithic microwave integrated circuits ) which made possible a new level of miniaturization at reduced cost.

Our first product was the model 8001 which was introduced in the November, 1989 issue of "Microwaves & RF" magazine. This unit weighed in at a tiny 2.5 lb. It was soon followed by the model 8002 which extended the frequency range of the 8001 from 2-8 to 2-10 GHz.

Next came the model 8003 which was featured on the cover of June, 1997 issue "Test and Measurement World". The 8003 extended the frequency range to 2-20 GHz. With the 8003 internal adjustments were eliminated in favor of digital correction for improved ease of calibration and frequency accuracy. A universal input, 90-250 VAC, power supply simplified use in the international marketplace. Subsequent to the 8003 have been models that extend frequency coverage down to 0.5 GHz and up to 26.5 GHz.