The uT3 hardware is short protected, so you can just throw a tube at it and run a QuickTest (QT). If the QT looks odd, a trace will often reveal more, and perhaps what is wrong (sometimes it's an oscillation). There are options for adding short and leakage tests. The most valuable of those IMO would be h-k leakage, which is a common failure. That could be done fairly easily, and it's on my list. You can of course look for shorts with a multimeter, and the life test on vintage testers is just a reading at reduced heater voltage, which is easy to replicate. See below for more uT vs. Hickok.dorrisant wrote: ↑Sun Apr 24, 2022 3:13 pm will the uTracers be able to replace my Hickok's? I am not so much worried about the gas test or life test, I can see how those are available with some extra thought and setup. But, will it test for shorts? Or do I need to run the tubes through another tester first?
You can save and recall the setup files that you create by clicking buttons on the main form, and they contain both the curve tracing and the QT parameters. They are easy to create, and I recommend that people make their own to become familiar with setting the tracer up. It doesn't take very long to accumulate files for all the common tubes. For the QT on any given tube, I look up the data sheet and pick off the parameters for the 250V spec point (which almost every data sheet has, in table format), and load them into the QT form. It has fields for entering the spec values, and calculations showing how far the DUT is from the spec are made when the test is run.
The typical Hickok and others, AFAIK, do not test at anything near actual operating voltages. The QT at 250V is about twice the Hickok service-type tester voltage IIRC, and you get more information. There are some Hickoks that can test at higher voltages. For example, the model 580 could test at up to 300V.dorrisant wrote: ↑Sun Apr 24, 2022 3:13 pm Would you, knowing what you know now, go for the uTracer 6 instead of version 3+? How often do you wish you had that extra plate voltage? How often do you see the extra current being beneficial? I know that you are limited by the maximum current, therefore limiting the plate voltage at times. I have seen tubes make it through two Hickok's only to arc like fireworks when used in the amp (MusicMan). I would think that being able to run big tubes at higher plate voltage would allow one to match the actual working conditions of the amp intended.
The uT3 goes to 400V, and in the high-current configuration it can go up to 1A. On Ronald's site, he recommends setting it up for 600mA if you want or need more current capability. That's how mine is configured now, and that's sufficient to make full traces of large power tubes at their typical screen voltages. The upper limit for Va and Vg2 is still 400V, but most data sheet curves do not go above that on the g2 voltage, and there really isn't much to see at higher anode voltages once the curves flatten out. IMO there is no compelling argument to keep a vintage tester around, other than as a collector's item.
I did think hard about building a uT6. Assembling the board would be quick and fun, but in the end I decided that the time and cost required to make a new enclosure and socket array would not be worth it for me. Also, I'm not sure how the two stack up if you consider the uT3's accuracy at low current vs. the value of additional current capability. I'm still thinking about an easy way to make the uT3 switch from high current to normal mode, which would be ideal. Like the uT3, the uT6 basic board can't do positive grid voltage, or a grid current measurement. There is a daughter board for the uT3 that allows Vg from -10 to +5V, and measuring of grid current for triodes. An accessory for the uT6 is currently under development.
I'm using an external heater supply with my uT3, and while the uT6 heater supply is an improvement, I understand that uT6 owners still prefer to use an external supply over the on-board supply. The good news is that there are some compact and inexpensive SMPS available for that. My setup uses the two small bench supplies I have, one for the main power and one for the heater. It is very nice to have heater current limited at start-up, and measure the tube heater current, and monitor the current drawn by the uTracer itself to be sure it is functioning as it should. That was particularly nice as I was going through all of the upgrades from the original uT3.
A comparison table is here: https://www.dos4ever.com/uTracer3/uTracer3_pag12.html Note that it's missing a reference to the low/positive Vg accessory for the uT3.
I'm really happy with the banana jack and patch cord system. Common tubes share pin-outs, so I can set those up quickly from memory. Some people have wired up a dedicated 12A_7 socket, which would be a nice time saver since that setup is very common, and among the most complex since both triodes are tested simultaneously. If you isolate the uTracer circuit ground from the enclosure, the danger of shorting the grid terminal to the case is eliminated. I just haven't gotten around to doing that yet.dorrisant wrote: ↑Sun Apr 24, 2022 3:13 pm I have gotten accustomed to the use of rotary switches for tube pin connections. I think I might want to use that with my own build. I could follow the convention of my 605A making use of the tube charts that already exist. I'd probably install banana jacks for each pin assignment just for the added flexibility. That would be the one thing I would add to what you've done so far. Add a rotary switch for g1... Right in the center of where you mounted the pin jacks, so that you could point the g1 "knob" at the pin jack you want it to feed. No jumper, no possibility of shorting it to anything.
I think I drove Ronald nuts will my questions, suggestions, and complaints about the uT3's shortcomings (as documented here in this thread). It did benefit from all that though, and it's a much better tool than it was when it was first released due to the many software and hardware improvements. For example, originally there was no QT, as Ronald didn't see any value in it. I lobbied hard for that, and even provided a drawing to lay out the form.
