[Amps] Bakelite on base of 3-400Z Tubes

[Richard]

>I found some old but good 3-400Z tubes.  A couple of
>them have a bakelite cover or attachement on the base.
> Anyone know what it was for?

To reduce the chance of glass fracture/vacuum-loss when some Turkey rocks 
the tube sideways during extraction and puts bending stress on the pins.  
[Amperex tubes do not need this because they use bubble-glass in the 
base, which is highly Turkey-resistant.]  

cheerz, Bill

-  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, 
www.vcnet.com/measures.  
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