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

[rbethman]

Les,

While I do not have the sophisticated temperature measuring 
capabilities, I have long suspected that the results you've posted was 
the case.

I long done away with those pesky shields, both in R-390As and SP-600s.

They DO seem to run cooler!

Bob - N0DGN

Les Locklear wrote:
> 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.
>