FETRONS
Fetrons were JFET-based devices made by Teledyne Semiconductor back in the Seventies and sold as direct replacements for many tube [English: valve] types. The original idea was to cut power consumption and heat generation in telephone offices, where there were literally thousands of tubes in carrier and repeater bays in every toll office. As the idea caught on, Teledyne sold Instrument Upgrade kits using Fetrons for oscilloscopes scopes (e.g. the HP400 and the CA plug-ins for Tektronix 500 series; probably others as well).
Compiler's note: Fetrons were certainly used in telephone repeater stations in New Zealand. Can anyone confirm if they were used in Britain as well?
