VACUTRACE Vacuum Tube Curve Tracer
9
controls as necessary until you have a full set of curves and the tube is running
safely within its ratings.
Limits
Three sweep limit controls are provided to prevent tube damage and allow you to
adjust the way you want the curves presented. The triode curves shown above are
power and voltage limited. The A/B mode curves shown below are both current and
voltage limited. Sometimes you will want to combine all three.
Modes
Tube matching is accomplished using the A/B mode. VacuTrace automatically
alternates sweeps between tube A and tube B displaying both sets of curves
simultaneously. Differences in tubes are readily apparent and it becomes obvious
that single point matching (such as current at a given bias) is insufficient. The Z-
axis intensity control modulates the B tube so that its curves appear dotted.
Switching to 2A mode connects both cathode sense resistors together thereby
doubling the current capability to 200mA. Note that while in A or 2A mode, the B
tube is cutoff by applying –70V to its grid. And, of course, vice versa.