[R-390] Tube shields? We don’t need any stinking tube shields!

[Les Locklear]

Groups,



This test was done using a Raytek laser digital thermometer. Temperatures 
were taken from a 6BZ6 1st RF amp tube on a John R. Leary SP-600JX no suffix 
number, serial number 1262. Ambient room temperature was 75°F. I’m not a 
scientist nor should this be misconstrued as a scientific test. I have 
always been curious as to whether the IERC tube shields “actually” prolong 
tube life. As noted there were several different tube shields used in this 
“test.” Also note there are several different types of inserts inside these 
tube shields.



The “Real McCoy” IERC Tube Shields have a finger grip type of insert that 
acts as a heat sink and the test results show that the temperature 
difference between the shield and the tube itself is little. That should 
tell us that that type of shield is the “Standard.” For your information, I 
don’t use tube shields and my tubes seem to last a long time.



Take this information as it’s meant to be, strictly informational.







  1.. Shiny metal Eby tube shield no insert. 94°, bare tube 124°F.


  2.. Shiny metal Eby tube shield with seven-sided black aluminum insert. 
96°F, bare tube 127°F.


  3.. Dull metal Elco tube shield no insert.108°F, bare tube 135°F.


  4.. Black heat resistant painted Eby tube shield no insert. 104°F, 126°F 
bare tube.


  5.. Black anodized Eby tube shield with “waveform, nine ridges” aluminum 
black heat shield insert. 107°F, bare tube 127°F.


  6.. Collins black anodized tube shield with “waveform, nine ridges” 
aluminum black heat shield. 100°F, bare tube 122°F.


  7.. W.P.M. tube shield with five-sided aluminum insert. 106°F, bare tube 
118°F.


  8.. IERC tube shield with “finger grip” type beryllium insert. “The 
Standard.” 102°F, bare tube 104°F. ( has to be the insert)


  9.. Bare tube, no shield. 6BZ6 114°F.
   YMMV


Les Locklear
Gulfport, Ms.
DX'ing Since '57
http://www.hammarlund.info/