The Hewlett-Packard engineers who designed the 5245L digital frequency counter in the 1960s weren’t satisfied with its being limited to a top frequency of 50 MHz. How about a plug-in that handles ten times that frequency—500 MHz—half a gigahertz? Now, how do you do that without any integrated circuits or transistors that run at that speed? Well, you reach deeply into the vault of magic circuitry where nothing is as it appears as it does at lower frequencies and attack the problem through the black arts.
DO NOT ATTEMPT DISASSEMBLY OF CAVITY