On 5/2/2013 3:32 PM, MU 4CX250B wrote:
I'm afraid I don't understand why the plate dissipation would affect
longevity, provided the tubes have adequate cooling. Exceeding rated
grid current or plate current, or using the wrong filament voltage
could kill the tubes, as could inadequate cooling, but I don't see
why running the tubes at their rated dissipation with plenty of air
would shorten tube life, if all other tube parameters were within
specs,
That's because you are interested in the emission capabilities. If it
wont even make the plate dissipation rating, something is wrong.
Look up the tube data sheet and see what the max plate current should
be. The tube should be capable of this figure as a minimum. You are
really checking the emission.
73
Roger (K8RI)
73,
Jim w8zr
Sent from my iPhone
On May 2, 2013, at 4:22 PM, Jeff Blaine <keepwalking188@yahoo.com> wrote:
I have used about 8 of the Chinese 572 specifically for torture testing in RTTY
service and I can say without qualification that the plate dissipation limit
(IIRC 160w) is not something which will keep the tube in long service. But
whipping the hell out of these tubes in AM/FM/RTTY service with all the guns
blazing is not the common application.
I would expect the current breed to give long SSB service as long as tuning is
done properly and kept to a minimum. For CW, almost as well. From there, it
goes down hill fast.
Comparing them with prior generations makes no sense because there are
virtually zero NOS old tubes remaining. You either buy the Chinese (through
some direct or distribution method) - and that is the only source available and
take what service life you can get. Or you can flip to another tube type at
some considerable amount of work and expense.
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