[Amps] 4-250a mounting

[R.Measures]

On Dec 25, 2005, at 12:27 PM, Peter Chadwick wrote:

> As I understand it, the filament structure is the same as the 3-500Z.

yes

> Not sure about filament to grid spacing,

I don't know the distance involved, but the filament to grid breakdown 
potential is typically 6000 to 8000 volts.

> but I have had some go grid to filament short when hot, and that's 
> with them mounted vertically. Depending how many tubes you have, it 
> could be worth trying. Rich Measures may have some historical 
> knowledge of 3-500 failure modes which could be applicable.

In my experiences, 3-500Zs typically fil--grid short at around the time 
that a big bang is heard.  Applying a short between the grid pin and a 
filament pin makes no sound.

> I think personally, I'd avoid it, but that's partially because I don't 
> have a lot of spares!

>
> 73
> Peter G3RZP
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>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org