Rated hours vs. real life...10 hours things lasting 50 years...

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In Reply to: Filaments and tube life posted by Rafe on September 24, 1999 at 10:51:35:

***When they say a tube has a 10,000 hour life span, do they mean that the filaments will last 10,000 hours, or the tube will last 10,000 hours with plate voltage applied?
It means exactly whatever the manufacturer decides it should mean - nothing more and nothing less. Usually you hope it would mean continuous duty under full load. That is how *prudent* guys rate their tubes.
I recently had the same question asked about the rated life hours. Unfortunately nobody has a formula that allows you to translate the rated hours into expected service life. However, you can make some general statements.
Consider, for instance, typical electrolytic capacitors used in many high-end products. Their rated life is often just 1000 hours. However, these parts will usually last for at least ten or fifteen years. That's 100,000 hours or so. Sure, they are not always on, but still...
You can buy today a Fisher or Scott with all original tubes still going strong after 50 or 60 years. Those tubes were probably rated 1000 hours.
That means that a tube with rated life time of 5000 hours should last on average many years (what that "many" means is your guess which is as good as mine). There are some rare tubes rated at 10,000 hours. One can presume then that these would last (many years)*2.
If you look around you will find some cases the are hard to believe. For example, a typical household electric drill is rated at about 10 hours service life. That maybe a shock, but if you open it up and look at its bearings, you are going to get an even stronger a shock. The Sears circular saw that I bought when I knew no better, had no finish on its shaft, and I mean NO FINISH. What it means is that I was not supposed to use it the way I did...

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Follow Ups Full Thread

Topic - Filaments and tube life - Rafe 10:51:35 09/24/99 (2)

Rated hours vs. real life...10 hours things lasting 50 years... - Victor Khomenko 11:12:51 09/24/99 (1)

Thanks for the info, but... - Rafe 13:06:31 09/24/99 (0)

Follow Ups

Rated hours vs. real life...10 hours things lasting 50 years... - Victor Khomenko 11:12:51 09/24/99 (1)

Thanks for the info, but... - Rafe 13:06:31 09/24/99 (0)

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