APS230, HPS10: Testing Test equipment?

As a MechE getting back to some electronics, I was pleased with the HPS10. User interface unlike what I had used but fairly logical, easy to use. Low performance, but I borrowed an HP signal generator and pumped 5 (V) squares. Various sites claimed 5(MHz b-w) or 2 (maybe single-shot.) The 10 looked OK to ~2(MHz squares).

But the APS230’s 2 channels, “60 (MS/sec) Single-shot … 30 (MHz b-w)”, $600 sounded OK for a 4(MHz) Atmel uCU project. [Or a $1.8k Fluke.]

Again the HP signal generator pumped 5 (V) squares. The 230 looked good to ~1(MHz). Marker/Cursors matched my Omega 29B VOMeter. GOOD. But Channel II’s on-screen Readout/Meter was 0.1(V) lower. One Channel had under-shoot rounding, but swapping probes showed 1 off. Tweaking the compensation cap matched both. (?)

But by ~5(MHz) leading edges had under-shoot rounding & more rise-time slope. My 230 unit showed sloping trapezoidal sides. By ~8 both channels looked like shark fins. Velleman’s Texas center says may have a firmware problem. They were helpful and I should get it back ~Feb10.

P.s. I checked the 1st HP sig gen on a college HP 400(MS/sec) scope and it was off. I then used a better unit. (Who’s paranoid!?)

Any techs or EEs out there test an APS230?

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