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Old 9th Aug 2018, 8:20 pm   #46
Radio Wrangler
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Location: Fife, Scotland, UK.
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Default Re: Back terminated cable?

Quote:
Originally Posted by Hartley118 View Post
I think that a lot of misunderstanding has been created in the minds of electronics students when generations of lecturers have explained loudspeaker matching in terms of the maximum power theorem. Maybe back in the day of low impedance triode output valves it could give a reasonable approximation, but ever since the pentode came along, it's been irrelevant and with transistor amplifiers could result in the release of much magic smoke!
I'm always very careful to reserve the word "matched" for when source and load impedances at some point are either exactly equal if resistive, or conjugates if complex.

In other circumstances i talk about loading and load impedance transformation, carefully skating around the m-word. It takes a fair while to get recent graduates to see that we don't actually match everything in RF engineering.

It does take some doing to undo some of the impressions people are given.

David
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