[Boatanchors] Question

[Al Klase]

Hi Gene,

Inserting questing, especially so as we werejust  pondering the internal 
shields in the middle of octal tube bases just this morning on the 
milsurplus reflector.

The continuing struggle in high-frequency amplifiers is to reduce the 
usually degenerative capacitive coupling between the plate and grid 
circuits.  The screen grid takes care of this inside the immediate tube 
structure, but thre's still coupling between the leads.  If you look at 
the base diagram for a typical RF tube, like a 6BA6, you'll find the 
signal grid and plate are on opposite sides.  Placing a grounded object 
in the middle of the socket reduces the unwanted coupling.

Al

On 2/18/2010 2:15 PM, WØQFC wrote:
> While rebuilding several old rigs and test equipment I have noticed that the
> instructions say to ground the center post of the 7 or 9 pin tube sockets.
>
> Is there any reason for this other than a convenient point to route the
> ground wire(s)?
>
> Any thoughts????
>
> Gene, WØQFC
> Spring Hill FL
>
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-- 
Al Klase - N3FRQ Jersey City, NJ http://www.skywaves.ar88.net/