>
>
>> The important thing is that the delay of an electronic trip can be
>> only a few milliseconds for *all* levels of overload. This is what an
>> electronic trip can do, but a fuse can not!
>
>Rich Measures suggests (or has suggested) using resistors to
>replace electronic systems, rather than using fuses.
>
// Close. I suggest replacing grid protect circuits - which have a
track record of failure - with a fast-acting fuse or a carbon-film
resistor.
>Fuses are bad enough. I can't imagine anyone depending on a
>conventional resistor to fuse a grid circuit.
// The AL-1500 seems to occasionally gold-sputter the 8877's grid. The
tube (s/n HSZ501) shown in the photograph at Figure 24 on my Web site was
one of four 8877s that failed in one AL-1500. Apparently, the
sophisticated electronic "protection" failed to protect.
// The mass of an 8877 grid is c. 50g. The mass of a 30? carbon-film
0.25w resistor is less than 0.3g. Which will heat faster if they are in
series?
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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