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Re: [Amps] SB-1000 - 3-500Z restoration

To: "W1WCI" <>, "AMPS" <>
Subject: Re: [Amps] SB-1000 - 3-500Z restoration
From: R.Measures <>
Date: Thu, 22 Jan 2004 23:17:50 -0800
List-post: <>

>Have a new old SB-1000 with a 3-500Z.  Turns on, lights up, HV ok, but 
>tube arcs and fuses blow.

**  How is it known that the tube arcs?

>Things checked:
>-looks good, nothing looks or smells cooked
>-new caps
>-diodes test ok
>-lights up ok without tube
>-transformer windings ok tested at 1000V
>Before the tube arcs (I hear it) 

**  If the arc makes a loud bang it is not inside the tube, it is in the 

>the tube glows at the base(10-30 
>seconds til arc).

**  What color is the glow?

>Have read about restoring tube by "running low anode voltages and 
>positive bias on the grid".  I guess I am asking how to do this?  

** Check tube (filament not lit) with a high-potential tester:  If the 
anode/grid leakage is under 10uA, and the grid-filament withstanding 
potential is >5000v, chances are good that the tube is too.  

 have phun, Tim
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