[Amps] Surge resistor

Rick Stealey rstealey at hotmail.com
Wed Mar 21 08:22:47 EST 2007


Tom, W8JI, says:
>The small glitch resistors in your amp don't do a darned thing

I am in the process of finishing up my 8877 amp, and the plans I am using 
show a 0.6 ohm 1 watter and a 50 ohm 50 watter in series.  So in the event 
of a flashover (milliseconds ?) the 0.5 ohmer is supposed to blow open?  I 
can't see the value of the 50 watter.  In case of extremely high plate 
current, such as hitting it with full drive and no load, say 2 amps of plate 
current flows and even then the big resistor only drops 100 volts, and heats 
up 200 watts. I wouldn't expect a wirewound power resistor to fail 
immediately under these circumstances, and I can't see how it is protecting 
anything.
What am I missing here?  Is the 50 watter the wrong type?

I have other topics to discuss relating to control circuitry, soon.

Rick  K2XT

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