[AMPS] AL-1500, AL-82, AL-1200, QRO???

[W8JI@contesting.com (Tom Rauch)]

Someone wrote:

> >> The 3cx1200A7 is virtually immune to grid/fil. shorts.  3-500Zs are
> >> not. 

Andy replied:
 
> I'd just like to counter that by saying that in 15 years of looking after
> the amps for our multi-multi contest group the ONLY fatal tube failures
> which I have seen have been 2 grid-filament shorts in 3CX1200A7s. I've
> probably been through 30 amps with various tubes in including


The 3CX1200A7 is probably the most reliable tube out there. 
Failures are very low. It is also one of the least stable, has high 
internal capacitance, and is moderately hard to drive. That's the 
tradeoff.

>From a manufacturing standpoint, the most common failure in a 
3CX1200 has been a grid-to-filament short. Second most common 
has been low emission (mostly in brand new tubes). All in all, it is 
a very reliable tube.
73, Tom W8JI
w8ji@contesting.com

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