uTracer NXT
Overview
The uTracer NXT is Ronald Dekker's next-generation DIY tube curve tracer — a modern redesign of the long-running uTracer3+, sharing the pulsed-HV principle with the higher-voltage uTracer6 and documented at dos4ever.com/uTracerlogNXT. It keeps the defining uTracer idea — instead of a bulky continuous HV supply, it pulses high voltage into the tube under test for about a millisecond while sampling plate/screen current, characterizing tubes above their continuous dissipation without damage — but rebuilds the electronics around current-production parts (the OPA227 and HV PNP transistors it replaced are going obsolete), folding in the uTracer6's proven NMOS high-voltage switch and a PGA-based front end while staying a through-hole kit on the uTracer3 board footprint. It sits in the mainstream ~500 V / few-hundred-mA envelope (the 3+'s band, not the 6's kilovolt territory). This dive tracks what the NXT is, how it differs from the uTracer3/6, the measurement theory, and the design updates, ahead of building the kit Jeff has on order.
Context
Paired with the uTracer6 and eTracer on the bench, the NXT is the newest generation of Dekker's pulsed tube tracer. Where the uTracer3+ was the mass-adopted hobby kit and the uTracer6 extended the plate-voltage envelope for sweep tubes, the NXT is a ground-up redesign. The Heathkit TT-1 (Gm go/no-go) and Supreme 385 (emission go/no-go) handle quick triage; the curve tracers produce the publishable curves and SPICE models. See the category primer at Curve Tracers — Overview.
