Science Fair Project Encyclopedia
The nuvistor is a type of vacuum tube announced by RCA in 1959. Most nuvistors are basically thimble shaped, but somewhat smaller than a thimble. Triodes and tetrodes were made, although tetrode nuvistors are rare. The tube is made entirely of metal and ceramic. Making nuvistors requires special equipment, since there is no intubation to pump gases out of the envelope. Instead, the entire structure is assembled, inserted into its metal envelope, sealed and processed in a large vacuum chamber with simple robotic devices.
Nuvistors are among the highest performing small signal receiving tubes. They feature excellent VHF and UHF performance plus low noise figures, and were widely used in 1960s televisions, radio equipment and high-fidelity equipment, primarily in RF sections. They competed with the solid state revolution, and along with GE's Compactron, probably held it at bay for a few years. One notorious application was in the Ampex MR-70, a costly studio tape recorder whose entire electronics section was based on nuvistors.
Example Nuvistor types:
- 7586 - First one released, medium mu triode
- 7587 - Sharp cutoff tetrode
- 8056 - triode for low plate voltages
- 8058 - triode, with plate cap & grid on shell, for UHF performance
- 7895 - 7586 with higher mu
- 6CW4 - high mu triode, most common one in consumer electronics
- 6DS4 - remote cutoff 6CW4
- 6DV4 - medium mu, intended as UHF oscillator, shell sometimes gold plated
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