> On Tue, 2006-06-27 at 12:22, Tom W8JI wrote:
>> You are reading more into the data sheet than it is
> It is somewhat disconcerting to have someone say the
> isn't a reliable source of information.
No one said that that I know of. Although I haven't been
reading all the posts, at least I certainly didn't say that!
What I said was someone wasn't reading the datasheet
correctly and applying the information correctly.
> I always assumed when it said something like
> RF Linear Amplifier
> Grounded Grid Class B
> Maximum Ratings
> DC Plate Current 0.400 AMP
> that's really what it meant. Now it seems maybe not!
> (Why would they put that in there? Did they just pull
> out of the air?)
> Maybe you could step back a little from the current debate
> and say a word about what the datasheet actually does say?
The data sheet is generated early in the design of a new
tube by looking at samples under certain limited test
conditions and by the design goals of the engineers.
Operation outside the exact letter of "typical operation"
is widely accepted and very common. Eimac and other
companies often OK operation outside the guidelines. The
data sheets themselves even state "If it is desired to
operate this tube under conditions different from those
given here, contact the factory......".
This entire worn out thread centers around two things, tube
life and operational performance.
As I said before and I'll say one last time:
1.) Everyone agrees tube life is NOT an issue.
2.) Multiple measurements show the tube very linear with the
load line established at 550mA, and it has far less IM than
any typical exciter with that load line.
3.) IM is caused by deviation in transfer characteristics,
NOT by following one constant current curve.
4.) The manual doesn't even tell people to operate at 550mA,
so that is a non-issue. They are told to establish the load
line at 550mA and back drive off to 400mA for operation
I really can't contribute anything else to this thread. I
think everything that needs to be said has been said several
times. People can always get a copy of "Care and Feeding of
Power Grid Tubes" and read much of what was said here in
that book (and read the book several times if they need to
see it over and over again).
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