547
The 547 is a 50MHz scope that takes letter-series and 1-series plug-ins. It has two identical timebases and , when used with the 1A1, 1A2, or 1A4, has the ability to display one input with one time scale and another input with a different time scale. The effect is similar to a dual-beam scope assuming that the input signals are repetitive. This "Sweep Switching" feature differentiates the 547 from the 546.
Triggering is done with tunnel diodes, which tend to shift in characteristics as the instrument ages.
A replacement CRT for the 547 can be taken from a 543B, 544, 545B, 546, or another 547. A common problem with 547's is the HV transformer. Rather than the wax used in older designs, the transformer was potted in a new epoxy resin, which turned out to absorb moisture over time when used in humid climates. Excessive leakages requires the regulator to drive the 6AU5 input oscillator tube (V800) harder. Eventually, the drive circuit can not supply enough power to keep the supply in regulation. The usual solution is to scavenge a replacement from another scope.
