[Hammarlund] purpose of tube shields

[Robert Ross]

On 2014-09-25, at 2:06 PM, Robert Sauvan wrote:

> Hi all,
> Can someone please explain to me what exactly is the purpose of tube shields? Are they for rf shielding? It seems to me that a major complaint about old tube radios is that they run so hot. As I have been working on my various radios, lately of course my HQ-180, I have spent a lot of time trying to swap tubes to find the "best" one for the radio. Or, even one that works. Of course, you let it warm up for a while to see if it works any better than the last tube you had in there, but, man they are hot! When I leave a shield off for testing purposes, the tube cools off really fast. Seems to me if the tube ran cooler, it might last longer. Im just plain curious!
> 
> Thanks-Bob-W0YBS
> __________________________


Bob:


  My understanding is that Tube Shields are meant to DISSIPATE HEAT from the Tube to the shield and then into the air. That's why the tube shields get so hot…they are doing their job by sucking the heat away from the tube!!!

That's how I was educated anyway……..

ROB VA3SW

Robert S. Ross
London, Ontario CANADA