Tubes Asylum

Why is there different shunt settings for a rectifier test

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Byrd69

A

I've sometimes wondered, and never came up with an explanation for the different shunt settings for a rectifier such as a 5Y3. 18 on one test, 22 on the other. For a 5U4G, the shunt is at 45 and 35. Other rectifiers are similar. But then there's the 5V4...85 and 85.

Anybody know?

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Follow Ups:

RE: Why is there different shunt settings for a rectifier test - Steve O 14:02:11 04/30/23 (1)
For a directly heated full-wave rectifier in the Hickok circuit, the cathode/anode voltage for one section will differ from that of the other by the heater voltage. In the case of a 5V rectifier like a 5Y3, one section has 5V more across it than the other section. Because the Hickok rectifier test circuit operates at a relatively low voltage, the heater voltage difference between sections will produce different readings for otherwise identical sections. Hickok chose to compensate for the differences by using different "shunt" values so the "reject" value on the meter is the same for both sections. Could just as easily have provided two different reject values in the chart data but this wouldn't allow for one rectifier reject value on the meter. The cathode/anode voltage in an indirectly heated full-wave rectifier is the same for both sections so the shunt values are the same also.
- RE: Why is there different shunt settings for a rectifier test - Tom Bavis 17:41:47 04/30/23 (0)
  Applies to all emission testers - since there's 5V more across one section, it would read higher if settings were the same. Does not apply to indirectly heated rectifiers like 5Z4, 5V4, 5AR4 - those have the same cathode voltage for both halves, and use the same setting.
  
  And before someone tries to correct me - the Hickock tests diodes for emission.
RE: Why is there different shunt settings for a rectifier test - Tre' 12:11:11 04/30/23 (0)
My 539B is the same. If the B+ is coming off one end of the filament vs. a cathode.....maybe. 5V4 is indirectly heated and has a cathode.

Tre'
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