[Amps] 1625

k7fm k7fm at teleport.com
Thu Feb 12 19:41:28 PST 2009


"The max rating for a 6AG7 is 300 V, so you ran them at 3.3 the max voltage! 
It must be one tough tube.  The plate dissapation is 9 watts"

The maximum plate voltage for the 6AG7 in grid driven configuration is 300 
volts.  Grounded grid configuration is quite different.  I know of no 
published ratings for that, but it was obvious that the 1,000 volts did not 
exceed their ability - because they ran for an extended period of time and 
were still putting out what appeared to be the same power as when I started. 
The tube shells are not discolored.  Although I have heard stories of 
inverting them and running them in either oil or water, I did neither.  I 
did not have a fan on them.

The tubes were free, I was poor, and I wanted to push the envelope (tube). 
While my friends in high school were driving 80 mph on windy roads, or 
riding motorcycles, my pushing the envelope simply involved running 4 tubes 
in a manner not specified by the RCA tube manual, at a power which may have 
exceeded the published plate diissipation.  I survived, it survived, and I 
learned a bit.

My only regret was that, since the tubes survived, I did not push the 
envelope far enough.  Until you push a tube to destruction, there is still 
more to be learned.  I have been following rules all my life.  Flying 
helicopters, I must keep the rotor blades within a certain rpm range.  Too 
slow, and I die.  Too fast and I die.  Abusing those tubes to destruction 
could have been my one bright spot of non-conformity.  Alas, I could not 
even see how red the plates were, so they were not a bright spot  Every once 
in awhile, I get the urge to bend the rules a bit.  It usually goes away, 
though.

Maybe I will get that amp out again and see what it can do.

73,  Colin  K7FM 



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