Hi, when I test somes tubes with a Superior TV-11, sometimes I see blue flash inside tube and the meter needle is crazy. But when I test these tubes in a Heatkit TC-1, all is ok. Tubes are bad or I have a bad tester?

Thank you.

Could be many things. If you are seeing sparks on the cathode, then the tester is overloading the tube. If you see a purple glow, then the tube is gassy (though it would also do this on other testers and in radios). Blue on the glass (usually dim, and quite deep in color, though sometimes pale, too) is simply a phenomenon of cathode rays. I do not believe that it has anything to do with gas in the tube (rather the lack of). Seems to almost be residue left on the glass and surfaces, but the way it glows leads me to believe otherwise, since it doesn't seem to 'select' particles or material, though it usually takes on a somewhat regular pattern.

At any rate, most likely your problem is the first one. If so, check for shorts, improper resistors, improper switch settings, etc. If I put a 12AU7 in my EICO 625 and set the SELECTOR switch (as it is labeled) to #4, the tube will spark and flash, and the meter will jump all over the place. The #4 position in my tester uses a very high current low resistance resistor at 200 volts. The rest of the settings use much higher resistances at lower voltages, thus subjecting the tube to less current.

Check resistors, capacitors, wiring, etc.

T.

Yes, you are right. Sparks came from cathode to grid. So I will have to check the tester for bad component. I think it's the LOAD potentiometer....

Thank you

:Could be many things. If you are seeing sparks on the cathode, then the tester is overloading the tube. If you see a purple glow, then the tube is gassy (though it would also do this on other testers and in radios). Blue on the glass (usually dim, and quite deep in color, though sometimes pale, too) is simply a phenomenon of cathode rays. I do not believe that it has anything to do with gas in the tube (rather the lack of). Seems to almost be residue left on the glass and surfaces, but the way it glows leads me to believe otherwise, since it doesn't seem to 'select' particles or material, though it usually takes on a somewhat regular pattern.
:
:At any rate, most likely your problem is the first one. If so, check for shorts, improper resistors, improper switch settings, etc. If I put a 12AU7 in my EICO 625 and set the SELECTOR switch (as it is labeled) to #4, the tube will spark and flash, and the meter will jump all over the place. The #4 position in my tester uses a very high current low resistance resistor at 200 volts. The rest of the settings use much higher resistances at lower voltages, thus subjecting the tube to less current.
:
:Check resistors, capacitors, wiring, etc.
:
:T.

Could possibly be. Check its operation with a meter, and be sure that the knob is attached properly. I don't have a schematic for this tester, so I couldn't tell you for sure. Anything having to do with current delivery to the tube will be suspect, though.

T.