ECC86
The ECC86 ( 6GM8 according to US-American typing) is a low-voltage double triode , which appeared on the tube market in 1958. The tube was developed for VHF pre- and mixer stages in car receivers and owes its origin to the fact that the transit frequencies of the alloyed germanium transistors of the time were too low for the VHF input and mixer circuits in the emerging VHF receivers of car radios .
The ECC86 is one of the few special tubes that could work directly with the low on-board voltage of the starter battery (12 or 6 V, maximum permissible anode voltage 30 V) thanks to the smallest electrode spacing and tension grid technology . Other electron tubes also required a mechanical inverter (the ' chopper cartridge ') which, with a transformer , rectifier and corresponding filter elements, ensured a high anode voltage. The elimination of this fault-prone assembly simplified the car radio circuit technology, ensured more reliability in operation and was the basis for a tried and tested hybrid assembly of many circuit designs from the late 1950s and early 1960s, with the ECC86 often the only electron tube in the otherwise already continuous car radios equipped with transistors. Despite the inherent low self-amplification of the tube, the concept had enough advantages over transistors. Manufacturing tolerances of the electrode system of the tube after a tube exchange often resulted in a readjustment of the receiver.
This tube is no longer produced today. It is traded as a spare part from old stocks (NOS tube) or as a used ECC86 tube.
Other examples of low-voltage special tubes for use in car receivers:
- EBF83 (IF standard pentode with two diode lines for AM demodulation)
- ECH83 (oscillator triode mixed heptode for AM applications)
- EF97 (ZF control pentode)
- EF98 ( IF and NF pentode)
Web links
- Data sheet of the ECC86 electron tube (PDF file; 369 kB)