Germanium transistors

Many Tektronix scopes from the 1960's contain germanium transistors. These transistors are prone to failure. In most cases, they can be replaced with modern general-purpose silicon bipolar transistors with no modification to the circuit. Reasonable silicon replacements for small-signal NPN and PNP germanium transistors are 2N3904 and 2N3906, respectively. When transistors appear in pairs in the original circuit (differential amplifier, Schmitt trigger) change the pair, not just one transistor.