[Boatanchors] Tube shields CORRECTION

[hwhall at compuserve.com]

 The IERC shields, and some variations on the type, were developed in response to studies of tube heat and reduced operating lifetime. Before that, it seems that shields were indeed simply to control interference to or from the tube. Electric Radio had an interesting article a few years ago on tube shields, and tube life versus temperature. There were some subtle issues discussed, like the transparency of different tube glasses to different IR wavelengths as plate heat increased, and the effects of objects surrounding a tube and its shield.

 
Wayne

 WB4OGM


-----Original Message-----
From: rbethman <rbethman at comcast.net>
To: boatanchors <boatanchors at mailman.qth.net>
Sent: Mon, May 26, 2014 10:40 am
Subject: Re: [Boatanchors] Tube shields CORRECTION


One reason for *some* shields, such as the *IERC* types, is that the are 
lined with a pleated liner that conducts heat to the same type metal 
outer piece.

The whole intention is to wick heat away from the tube at a faster rate 
than simple convection.

These also have a base that is also designed to work as a complete unit.

The tubes with these run significantly cooler that the shiny nickel or 
chrome plated ones.

Bob - N0DGN

On 5/25/2014 6:48 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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