[R-390] Collins R-390-A Photos sought

[Flowertime01 at wmconnect.com]

Tom,

Black tube shields per say are not bad.

What you are looking for is a sleeve inside the shield. This sleeve is 
"corrugated"
so it contacts both the tube and the shield. This extra chunk of metal 
carries more heat away from the tube than just the air gap between the tube and the 
shield. In fact in the production metal shields, the air gap act like a dead 
air cavity and actually causes the tube to run hotter than when you remove the 
shield.

Some black tube shields radiate more heat away than other black shields or 
silver shields. Read some of the Pearls or Wisdom on the R390 page for lots of 
detail.
Once you learn a bit about brands and paint you understand which shields will 
be useful in removing heat as well as providing RF isolation. 

Careful about talking about tube shields on the R390 reflector. You may 
stumble over a dead horse there and it would be beaten again. If there is something 
you do want to know, Please do ask. Worry not about the dead horse. He is 
dead and feels little.

Once you get back to the R390/A for cleanup and alignment, you may want to 
solid state the 26Z5's just because it removes the filament heat of those two 
tubes from under the chassis. 

Roger AI4NI