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Post by doctorice on Jul 20, 2009 13:10:04 GMT -7
Some years ago I got a couple old tube testers on eBay. Both include transconductance measurement capabilities, or at least they appear to. They power up, and I've tested some tubes. Some registered as good; others had problems. I infer that the gadgets are at least partially working.
For the experts: (1) any tips on using these? (2) Any resources for calibrating them? I do have the manuals, but I think this job is better suited for someone with more electronics acumen than I have. (3) How reliable/accurate?
Thanks for any help.
Mike
PS: One is a B&K, the second is branded Superior.
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Post by Paul (TRANE) on Jul 21, 2009 14:08:56 GMT -7
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jacco
New Member
Posts: 5
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Post by jacco on Jul 23, 2009 3:33:29 GMT -7
Hi Mike,
Tube testers were never intended to be very accurate but only to give an indication if a tube was to be replaced or not, even the higher regarded mutual conductance testers. Of course there are testers which are known to be more accurate than others. What model are your testers? Regarding accuracy: most testers need to be calibrated every year. Search for someone on the net who can do this for you. Then get to know your tester by buying some tubes with known results and compare them with the results of your tester.
Good luck,
Jacco Netherlands
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Post by myles on Jul 23, 2009 12:18:04 GMT -7
I can supply a 12AX7 tube that would have the following known info so you can see what your tester says:
1. Plate Current 2. Transconductance / mutual conductance 3. Plate resistance 4. True gain in circuit
I can also provide via a .jpg a photo of the traces of the tube on a vacuum tube curve tracer if that would be of interest as well.
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Post by doctorice on Jul 23, 2009 15:53:27 GMT -7
I can supply a 12AX7 tube that would have the following known info so you can see what your tester says: 1. Plate Current 2. Transconductance / mutual conductance 3. Plate resistance 4. True gain in circuit I can also provide via a .jpg a photo of the traces of the tube on a vacuum tube curve tracer if that would be of interest as well. Myles: that would be terrific. I will learn a lot. I'll PM you. Thanks. Mike
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Post by doctorice on Jul 23, 2009 15:58:23 GMT -7
Paul G. and Jacco: thanks also for your suggestions. Much appreciated.
Mike
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Post by myles on Jul 23, 2009 18:46:21 GMT -7
I can supply a 12AX7 tube that would have the following known info so you can see what your tester says: 1. Plate Current 2. Transconductance / mutual conductance 3. Plate resistance 4. True gain in circuit I can also provide via a .jpg a photo of the traces of the tube on a vacuum tube curve tracer if that would be of interest as well. Myles: that would be terrific. I will learn a lot. I'll PM you. Thanks. Mike Mike ... just answered your PM.
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