[AMPS] Amplifier Experiments!

Rich Measures measures@vc.net
Mon, 25 May 98 11:56:26 -0800

>>> Well, it would be difficult for my bandswitch to fail as it is a big B&W 
>>> coil/bandswitch unit.  And no, no other stuff.  I did have a weird thing 
>>> happen that blew out some resistors a couple of weeks ago.  But it turns 
>>> out that the tube was bad.  IMHO, it had to have been an oscillation with 
>>> "unseen" stuff, but again, it was a bad tube.
>>As you found out, most of the failures attributed to "parasitics" are 
>>really just component failures. You change the bad part, and add some 
>>needless voodoo, and the thing works.
>Hmm...read again, Tom.  I think my failure WAS a parasitic of some sort.  
>To make a 3 watt, 1 Ohm metal film resistor fail, one would need several 
>amps of current.  

At least 3A because they will dissipate 12w (3.46A) for 1 hour in free 
air and remain within 10% tolerance.  

>To make a parallel combination of a one ohm 3 watt and 
>a one ohm 2 watt fail, one would need far more current than is probably 

Indeed, Jon.  The one ohm 2w Matsushita MOF resistors will carry 2.5A for 
1 hour (6.25w) in free air and remain within 10% tolerance.  It seems to 
me that if a parallel combo of the 2w and 3w 1 ohm units are used, it 
would take something out of the ordinary to blow them.  


R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures  

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