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Is it the TDSL app that limits mu ?Pillo69 wrote:Peterh, how to solve the amplification (mu) of a high-gain pentode ??.
For example, EF184 has a mu of 5250 and in the "Name" box in the "Quick Test" only allows a maximum of 1000.
Ok, it's in the 3.11 GUI .Pillo69 wrote:Limiting "mu" is the version uTracer v3p11 the program.
I enter 5250 value, perform pulse test, text box appears, and value is changed to 1000.
1000 is the maximum value.
Pillo69 wrote:Anyway I checked other valves in Datahet and "mu" value is the amplification factor.
For example 12AX7 the "mu" value is 100.
Therefore in EF184 the "mu" value should be 60 (according Datashet), not 5250 as indicated TDSL.
It must be an error in the TDSL program.
peterh wrote:Tube Nube wrote:There's something mildly amusing about a tube tester that uses silicon chips.
>>A tube "tester" is either to simple to be of any value, or to simple to be of any general value.<< Snippage
Well... and a simple answer may not be so.
A well made GM tester does many things well, but, yes, it does not trace curves, agreed. Nor, for a fact, do most audio applications require curves to be traced. A typical audio tube is far too crude a device for to be of much benefit. The best analogy that applies is a choke on a shotgun. One will never get the spread down to to the diameter of the barrel, one might get it to scatter a bit less over a short range, but a shotgun remains a shotgun.
I keep a Hickok 539B, a lab-grade tester that I obtained (legitimately) from the GE Re-entry Systems Division in Philadelphia some time after they closed their doors, fully calibrated, and with a set of calibration tubes as well. Using external meters, I can test for plate current, filament current and voltage, set specific bias voltages and thereby actually "match" tubes. No, again, I cannot trace a performance curve. But, the 539B is a fine tester, and within the universe of commercially manufactured units from back in the day, is surpassed only by (and perhaps) the AVO testers from England, and its newer brother, the 539C. No chips, of course. BUT, I have solid-state rectifiers in place, explicitly necessary for the 83 mercury rectifier not rated to be used horizontally, and also notoriously unreliable. The 5Y3 is a bit more reliable, but replacing it with a SS device is simple and certain.
But, within the broad range of tubes free of basic failures (shorts, gas, saturated cathodes and such, all of which would be manifest on a good tester), the best test for any given tube is the equipment it is in.
I am by no means a Luddite, and I see great appeal in a curve tester such that if I were to be designing new tube equipment such would be in my equipment inventory. But, I do not. I keep several dozen tube devices, mostly vintage radios, but also two complete tube-based audio systems including a Scott LK150. Nothing exotic however. None of it requires screening tubes with the precision that a curve-tracer would offer.
