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Re: [Amps] Failure of a pair of FU728F

Subject: Re: [Amps] Failure of a pair of FU728F
Date: Fri, 20 Sep 2019 07:14:47 -0500
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I believe that the tuning of a tetrode is different than a triode - correct? Are they tetrodes less reliable or more finicky?

John KK9A

Jay Terleski WX0B wrote:

I get a kick out of this tube thread. But let me try to add some sanity to
the weirdness of it.

There is no way we, Array Solutions, told anyone to run the amp at or near
the high power limit to avoid cooking the tube.
Just tune it normally and keep the screen current at zero ma.  Your gonna
be OK at lower power output.
Also with these tubes you want to make sure your filaments are very close
to 9V.   So watch the mains voltage. many parts of the country are getting
wall over 247V AC mains and that means your filaments may be running high.

Best wishes to the group.
Jay, WX0B

Jay Terleski
Array Solutions
214 954 7140

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