As early as 1977, HP commenced manufacture of the HP856x spectrum analyzers to enrich its RF power meters and sensors capable of measuring indicators in extra of 20 GHz. HP also produced configurable chassis based sweep turbines capable of making indicators to 20 GHz. Other T&M products of the time https://businessbookmark.com/story3050287/the-fact-about-hp-%D8%AF%D8%B1-%D9%BE%D8%B2%D8%B4%DA%A9%DB%8C-%D9%85%D8%AE%D9%81%D9%81-%DA%86%DB%8C%D8%B3%D8%AA-that-no-one-is-suggesting