Test Equipment Plus was started in 1996 with the idea of providing quality used test equipment at affordable prices. In 2006, the company expanded its focus by designing and manufacturing a color LCD display retrofit kit to support the HP® 8566A, 8566B, 8568A, and 8568B spectrum analyzers. Test Equipment Plus also began offering a repair service for HP®/Agilent® step attenuators. The following year, in 2007, the company designed and began manufacturing another color LCD display retrofit kit to support the HP®/Agilent® 8560 series spectrum analyzers. At the same time Test Equipment Plus also decided to play to its strengths, and began offering test equipment repair services for spectrum analyzers, network analyzers, and signal generators. The repair segment of the business now generates more revenue than used test equipment sales.

The LCD kits were well received so, in 2009, it was decided to design a compact, lightweight, and inexpensive spectrum analyzer. The goal was to provide a spectrum analyzer with a better price-performance ratio than anything else on the market. That goal has been achieved with the Signal Hound product line (analyzers USB-SA44B, USB-SA124A, USB-SA124B and tracking generators USB-TG44A, USB-TG124A.

On June 28th, 2013, the Signal Hound portable spectrum analyzers USB-SA44B and USB-SA124B developed and produced by Test Equipment Plus, Inc. got entries in the State Register of Measuring Instruments that is supervised by the Russian Technical Regulation and Metrology Agency (Certificate US.C.35.010.A № 51316).