[Hallicrafters] Blue glowing tube rectifier???

[Fred Olsen]

kwylow zinjanthropus wrote:
> All: My SX-28's 5Z3/83 tube has a bluish tinge to it.

Cal, the 83 is a full-wave mercury-vapor rectifier, and as John pointed 
out the blue glow is normal.  There is no "5Z3/83" tube, as in an 
interchangeable replacement.  The 5Z3 is a vacuum rectifier which is 
similar but not equal to the 83; it's roughly a four-pin 5U4.

The major difference is that a merc typically has a much lower forward 
voltage drop and will therefore contribute to better regulation in a 
circuit with high or varying B+ current draw.  The down side is that the 
mercs are becoming expensive and they are a bit delicate.  They should 
be run, or at least warmed up, vertically - base down (yes, Hickok had 
it wrong in all those tube testers) so that they don't short from a 
stray puddle; and they should be warmed up for 30 seconds at least 
before seeing full load current.

A particular unit may indeed be able to use either tube, in which case 
use of the 5Z3 may be preferable so that you don't have to fight over 
the 83s with the folks with Hickoks.  ;<)  Note that the 5Z3, or any 
other high-vacuum rectifier, should not glow and I suspect that's what 
is referred to in the GRR-2 manual.

Fred
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Outgoing checked by Norton AV