Tunnel diodes

Tunnel diodes are used in various timing circuits in Tek gear made from the early 1960's until the 1980's. Tunnel diode characteristics (peak and valley voltages and currents) tend to drift. Usually this can be handled by adjusting the surrounding circuit. Sometimes tunnel diodes completely fail. Replacement usually involves scavenging a similar tunnel diode from some other device. There are some people in the Tek community who may have some tunnel diodes they can sell.