[Top] [All Lists]

[AMPS] SB-1000 mods?

To: <>
Subject: [AMPS] SB-1000 mods?
From: (2)
Date: Sat, 8 Sep 2001 09:42:00 -0700
> > ... work, but thousands are in use. I have always added
>> Rich's grid fuse resistor scheme when repairing SB-1000's.
>> No tube failures to date that I know of.
>You'd be far better off to use a HV glitch resistor, and leave the grid 

//  Tom professed that using a directly-grounded grid increases the grid 
resonant frequency, and therefore increases VHF stability.  I checked 
this out with a dipmeter.  There is virtually no difference in res, freq. 
 Also, our retrofit kits include a glitch resistor.  

>Resistors in grid leads are bad news unless there is 
>good reason to add them, 

//  Such as one does not have a free supply of new tubes,  

> because they let the grid rise to anode 
>voltage if there is a fault.
//  Does this make sence?  The breakdown potential in a 3-500Z is 
typically >>20kV.

>If the grid rises to anode voltage, the grid naturally no longer 
>shields the filament from the HV surge. That means the filament is 
>many times more likely to rise to B+ rail.
//  This statement causeth me to rail.

>Better to simply put a proper surge resistor in the HV lead, and let 
>the arc pull the anode low through a series resistance!!!
//   ¿?

-  R. L. Measures, 805.386.3734,AG6K,  

FAQ on WWW:     
Administrative requests:

<Prev in Thread] Current Thread [Next in Thread>