[Boatanchors] Tube shields

[John Duffield]

Hi Bob

The silver/chrome shields are primarily to hold the tubes in the socket, 
with the little spring thingeys.... and also there is shielding as you 
mention.  Heat tends to build up in these shields, and you also see the 
'matt black' shields, with contact liners inside the shield body, which 
are intended to conduct heat away from the glass envelope, reducing the 
heat within the tube, but those little suckers get really hot when they 
are working properly.  These black shields also have retention fingers 
at the bottom, and they hold the tubes in place as well.

I suppose there is 'chimney effect' air movement in the chrome shields, 
but they don't usually serve to reduce the tube envelope temperatures.

73

John
K0KHZ
On 5/25/2014 4:48 PM, Bob Jackson wrote:
> I always assumed that tube shields were used to keep stray RF either in or out of the tube or both. Are there other reasons as well like keeping them securely in their sockets via the little springs inside the shield?
>
> Bob
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