12-22-2016, 01:21 PM
I think the failure rate of the 6X5G has more to do with its age and hours of service rather than an inherent defect. The basic design is identical to the 84/6Z4, 6X5GT and the miniature 6X4.
A 6X5G is just an 84/6Z4 with an octal base.
Since the 6X5G has not been made since the early 40's, chances are any 6X5G you find in a radio has many hours of use and is therefore more prone to failure. Of course, running the tube the way Zenith does at or close to its maximum ratings doesn't help either.
Typically what happens is that the filament insulating coating breaks down from the repeated expansion and contraction of heating and cooling and eventually shorts to the cathode. This shorts the B+ line to ground and takes the power transformer with it.
A new unused 6X5G should be just as reliable as a new 84/6Z4, 6X5GT or 6X4.
A 6X5G is just an 84/6Z4 with an octal base.
Since the 6X5G has not been made since the early 40's, chances are any 6X5G you find in a radio has many hours of use and is therefore more prone to failure. Of course, running the tube the way Zenith does at or close to its maximum ratings doesn't help either.
Typically what happens is that the filament insulating coating breaks down from the repeated expansion and contraction of heating and cooling and eventually shorts to the cathode. This shorts the B+ line to ground and takes the power transformer with it.
A new unused 6X5G should be just as reliable as a new 84/6Z4, 6X5GT or 6X4.
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