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I often see sellers quoting 1050mu equals new on my tv7 and minimum is xxx, Where does one find this information for various tube testers ?
To be more specific I would like to find this information for the BK606 tester. I have a supposed serviced / calibrated 606 tester and testing tubes it seems to work fine but I have no way of knowing if a reading of 82 on this tester equals a new tube or a tube that is close to XXX
any help appreciated
Follow Ups:
Hmmm...well, the B & K 606 is not a mutual conductance tester, so you cannot determine if a tube has GM equal to a NOS tube.
If you had a GM tester, then rule of thumb is to divide the minimum reading by 60 - 65% to get a NOS equivalent.
So, if the minimum read is 50 on an arbitrary meter, then 50/.65 = 77 and 50/.6 = 83 and 77 - 83 would be the NOS range.
To make life even more fun, those testers test for the service the tube was designed for. My fav example is 6DJ8 triodes were designed for cascode, VHF RF amplification.
An easy solution you can try is to buy a "tested" new tube, the type you use the most of and test it in your tester.
bob
"He (R.M. Nixon) was a foul caricature of himself, a man with no soul, no inner convictions, with the integrity of a hyena, and the style of a poison toad." H. S. Thompson
Thank you all for the clarification........
If I am not mistaken, your tester's scales goes from 0 to 120. Thus, indicating that a reading of 100 or more is for a new tube. However, tube testers have variations in readings even between the same model tester and even new tubes can test lower than 100. For small signal tubes, 12ax7, etc, this reading is good enough if you are concerned with matched sections. For power tubes the readings can be far off for matching where the current consumption of the tube also needs to be matched especially in a push pull amplifier. cheers, Dak
Generalizing, tube testers either perform transconductance or emission tests.Mu, as in the 1050mu equals new mentioned in your example, is a unit of measurement that pertains to transconductance. Your B&K falls into the emission camp. It applies an emission test that does not indicate nor correspond to transconductance. Thus for your tube tester you will not find mu values that relate to as new, good used condition, or throwaway tubes.
Per using your tester to determine how much use a tube had. Likely you will only be able to make a rough guess. Tube manufacturers did not specify a quantitative emission value for new tubes. In their lab, B&K may have tested a number of tubes of each tube type. Based on their results they might have made guesses on emission values that correspond to new tubes.
If the good range of your tester's meter has a scale of numbers including 100 than those numbers might indicate the percentage of emissions relative to B&K's guess of the emission value a new tube of a particular tube type would measure on their machine. No one can say if that is what B&K did nor know how far from being in the ballpark their emission guesstimates are.
Tubesound has an informative article about your B&K 606. Check it out.
Edits: 03/14/16 03/14/16
The information is provided on the TV7 charts and is specific only to that tester. Or course it's calibration comes into play. If that is off then those numbers mean nothing. A good reason to buy tubes from dealers that test under working conditions. Jim McShane comes to mind.
Edits: 03/14/16 03/14/16
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