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Re: [Amps] Drake L4 with 3-400Z photos

To: Bill Fuqua <wlfuqu00@uky.edu>
Subject: Re: [Amps] Drake L4 with 3-400Z photos
From: Jason Buchanan <jsb@digistar.com>
Date: Fri, 14 Oct 2005 13:11:02 -0400
List-post: <mailto:amps@contesting.com>
Bill Fuqua wrote:

>         Oh yes, about the photos,  it looks like the glass envelope of 
>tube on the left is scintillating due to electron bombardment. Nice red 
>anodes as well.
>  
>

It's very old - 1966 vintage - I think someone rode it hard and put it 
away wet as with simple keydown ZSAC it glows brightly in that one 
spot.  The newer tube to the right is equal in its appearance all the 
way around.  I have the matching tube to the one on the right but when 
it gets hot (long duration orange color) the connection appears to break 
between the anode and the plate supply (not sure if this is possible) as 
the plate goes back to gray color and the other tube picks up the load.  
Not a good situation.  So I put it on a shelf as an expensive ornament 
and use the older one on the left.  If I run the L4 at lower voltage the 
plate never gets warm enough to cause this to happen but it's enough to 
make me concerned against using it.  I wish I could find another 3-400Z 
to replace the one on the left.


73 Jason N1SU

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