One has come in to our realm. We do some high end audio so having something like this desirable. It was bought surplus on the cheap. It is not dead, but I am pretty sure it is not working correctly. I've yet to completely learn to work the thing actually, and am taking it slow.

First off, I DO know the basic tenets of a distortion meter. It filters out the fundamental frequency and measures what remains. Not quite rocket science. Unfamiliar territory for me indeed, but I should be able to understand this.

I am looking for failure modes, tips on operation and basic self checks and so forth. I have only gotten so far in the manual but I am on it. The way I see it, these things you take a sine wave, put it through whatever and calibrate the distortion meter somehow. Like set it to full scale, flip the switch and you get the distortion reading.

I cannot get it to act right, at least what I think shoud be right. I have actually confirmed that it does detect distortion. Instead of the onboard oscillator I used my Wavetek 111. Not the greatest but good enough for what I wanted to do. I got the thing to give a useful meter indication and switched waveforms. I switched to triangle from sine and the needle didn't go up.. OK, now realy I am not sure if the peak/RMS value of a triangle wave is less or more than a sine wave. And I fully expected the square wave to peg the meter, which it did.

Until I hit this other waveform on it, looks like _/|_/|_/| and saw the needle rise could I be sure this thing is anywhere near being able to really measure distortion. I don't care what, that half sawtooth with the 50 % dead time will deflect any measuring device less whether it measures average, RMS, peak or smegma. PLUS the thing is only positive going, so the peak value is half. And yet the needle moved up.

I consider that a good sign. The Wavetek 111 info is available at BAMA if you want to really see the waveform. And it is that waveform like, exactly.

Another thing I am noticing is that when you change certain settings the needle pegs and takes a few seconds to settle back down. Now, with HP I am not impressed. some of their designs, certain other things and their ideas of the human interface, I think suck. but the fact is they built this, not me and no matter what I think about some of their dowside, I do not bleieve they designed the thing so it would peg the meter on things like range changes. Mode changes. Like from input to distortion.

We did a quick visual on it, there is nothing spilled inside, no burn marks, bulging caps or anyhing of the sort. Of course this is going to be done again but we stuck the lid back on to see how it works.

Other thing is that it has some broken knobs. I can deal with that until some come along, as long as the thing works.

But really, ike known good test ways ? I am not talking MBS here, just a basic test. Like if I switch from sine to square, is there a number that it should read like 50 % or something ? I mean like at a standard say 1 KHz and a specified rise/fall time. Can we get close somehow ? Like if you buy a used ohmmeter off someone that is supposed to work you would take a resistor and check it to see the thing actually works.

Actually a test like that is what I am really after. And of course whatever else might help this thing stay out the dumpster. Calibration attempts later.