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#1
08-24-2013, 10:52 PM
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Testing Compactrons
I've been testing a box of tubes I have on my newly acquired B&K 667. About half are compactrons. A couple of them have one side test a lot higher than the other. The low sides test barely in the green, the other tests about in the middle.
Do all the sections of one tube need to test nearly the same to be keepers? Or, is it acceptable to have one a lot lower than the other? 
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#2
08-24-2013, 11:15 PM
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Each section should test good per the specs for that section. Think of them as separate tubes that just happen to share the same vacuum.
Just make sure you aren't leaving some settings set for one section when you test the other. (Sounds like you aren't making this mistake, just mentioning it because I have done it once or twice.)
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#3
08-25-2013, 01:11 PM
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Thanks, I figured that was the case but I wanted to make sure. I'll put them in with the good, but mark them as one side weaker than the other. Yes, I'm changing the settings on each section, but you're right it's easy to forget to reset the lockout switches.
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#4
08-25-2013, 04:13 PM
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I would mark them as questionable. A tube can test
weak & still work fine. Also if you are subbing it to a dead tube it makes a good test. We had a B&K checker at the shop. We never used it, it was for the customers. Made more money on that than new TV sales back in the 70's & we sold a lot of new TV's. Bottom line a tube checker can find some bad tubes like open filaments or dead shorts. Whether it will oscillate or handle 500V spikes NOT. A checker, even the best is just a helper & not the final word. 73 Zeno 
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#6
08-31-2013, 04:29 PM
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Quote:
Before doing anything else (most the time) I could turn around & pull a new tube from a shelf 8' long & 6' high packed with tubes. That & the TV is the best tube tester. The hobbyist rarely has that option. The tester is useful but has limitations. They will not take a 6HA5 & see if it amplifies at 200 mc. Nor a 6EA8 & see if it oscillates at 200mc. It wont run a 6LB6 with 1KV spikes & 300ma cathode current. It will find open filaments dead shorts some intermitant shorts ( hold the tube in & flick it with your finger nail or tap with something) emission (can be low & still work fine) Bottom line is use it but assume it may be lying. It can help you or get you spending time & $$ for not. 73 Zeno
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