On 5/14/2010 9:29 PM, Al Gulseth wrote:
"4.22 A transistor protected by a fast -acting fuse will protect the fuse by
blowing first."
(Taken from "The Contributions of Edsel Murphy to the Understanding of the
Behavior of Inanimate Objects" by D. L. Klipstein, EEE Magazine, August 1967)
TNX/73, Al
Working with 1 KW solid state servo amps in about 1964, I came to a
different conclusion. I concluded that the fastest silver element fuse
was a reliable indicator that the protected transistor had already
shorted. Fortunately power transistors these days have more margin for
abuse, especially the RF power transistors chosen by Tentec which can
tolerate a high swr and need only thermal protection when the load
causes high collector current.
I'm working up an article for the 2010 Central States VHF conference on
PA protection. Has to be done and submitted in 8 days.
73, Jerry, K0CQ
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