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In Reply to: RE: 845 posted by Triode_Kingdom on July 20, 2015 at 18:10:21
Ok, can I politely ask what it is you are saying so we are on the same page? What specifically can't we test for?
Of course the ultimate test is always in the product. But using a tester that does not normally provide for an 845 could be reasonably used by adopting some sort of adaptor. This tester at say half the USUAL operating voltage of the tube and at the same or if possible even higher current but within the ratings of the tube should provide an extremely high degree of confidence that he tube is good and doing what it was designed to do.
In addition, a good tester can provide other performance information such as actual curves etc (some testers at least). But let's face it, often the user is only interested in whether the tube actually works, heaters etc and that the tube has good emission.
My position (in response to the poster's question) is simply that the idea of some form of tube adaptor is very valid and useful. Some testers even provide means of testing tubes that are not fully catered for, clip leads etc.
Naz
Follow Ups:
"This tester at say half the USUAL operating voltage of the tube and at the same or if possible even higher current but within the ratings of the tube should provide an extremely high degree of confidence"
None of my testers will output 500V/100ma. I think you're changing the parameters to suit an opinion that was incorrect in its original context.
"My position (in response to the poster's question) is simply that the idea of some form of tube adaptor is very valid and useful."
But it won't guarantee that a high power tube will be operational or satisfactory in service.
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Buy Chinese. Bury freedom.
If a tester can test an output tube like a 300B or the like then it's capable of a meaningful test of an 845 with some adaptation. Whether it's 500V or even 300V, 100mA or 40mA it really doesn't matter, just refer to the curves on the data sheet.
You can test any tube at much less current than would be considered "normal". In fact I've seen many designs that run tubes at a tenth of the current with great results but before you go off, no they weren't output tubes.
I'll repeat, is it possible that the tube may fail at higher voltages and current? Possible but absolutely minimal. Your solution is to plug the tube into an amp. What if it has an H/C short, certainly a greater risk.
I keep asking you to tell me the parameters that couldn't be tested but you keep offering the same line with no substance.
Remember that I qualified my original reply with "it depends on your goals". You should have taken note before jumping all over it.
You hold your opinion and I'll hold mine.
Naz
"I keep asking you to tell me the parameters that couldn't be tested but you keep offering the same line with no substance."Everyone in the business has seen tubes that test fine but fail to work properly in live circuits. Are you willing to guarantee that every 211/845/813/811 that tests OK at 500V won't arc at 1KV? What about 6L6s or 6L6GCs? Every example that seems OK at half anode voltage will also be OK at the manufacturer's rating? If you say "yes" to this, it only means your experience is too limited to know better.
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Buy Chinese. Bury freedom.
Edits: 07/23/15
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