Steve: how much hi voltage do you have. ?? With 300 watts out it sounds like
you might have one dead tube. How much grid current do you see?? should be
less than half scale (100) ma. with two good tubes and proper loading. Run
it with one tube removed and see what you get, then switch tubes and see
what you get !!! If nothing else you can pinch hit with a pair of 811A's ,
but don't hold the key down or you'll lose them .. ! i've done that a few
times for test purposes. the 811a isn't supposed to run at 2200 or so, but
as i said, if you don't hold the key down for more than a few seconds
they'll survive.
the normal grid current for one tube is 50 ma..
you might have some blown grid resistors also , so check those out. 33 ohms
is the original value.
Whatever You Do, Watch that hi-voltage, it'll rattle ur teeth and other
more serious things, but then I hope you already know that !!!!
I have the book on the 200 so if i can help let me know.!!!
It would be thursday before I could copy any part of it but let me know
what i can do for you!!!
carl / kz5ca
----- Original Message -----
From: "Steve Woodruff" <sjwoodr@yahoo.com>
To: <amps@contesting.com>
Sent: Monday, November 04, 2002 4:01 PM
Subject: [Amps] troubleshooting a sb200
> I'm getting lower than expected output from
> a sb200 (abt 300w with 100w drive). Tubes
> are 6-7, maybe 8 years old. Can someone point
> me to a reference that has some steps that i
> can take to determine the health of this amp?
> Measurements to take and such like... I don't
> have a tube tester, but if some feel that is
> a probable fault area then i'll find someone
> locally who does have one. Unfortunately i
> do not have the original manual.
>
> Thanks,
>
> Steve, N9OH
>
>
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