[AMPS] AL1500

2 2@vc.net
Sun, 9 Dec 2001 07:51:57 -0800


>
>
>> 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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