Help figuring current capacity

[jon]

After looking around on the web I have found that most of these transformers were rated in the 5-600mA range. This falls in line with the fact that a pair of 7591A's draw about 100mA of current in cathode bias.

[martin manning]

Per the data sheet, each 7591 probably draws ~43 mA at the voltages shown on the Fisher schematic. That would make it 172 for 4, and then 172*3.6 = 620. That seems to be consistent with what you found.

To get to 620 mA using Duguid's method the secondary resistance would need to be 2.4 ohms instead of the 5.3 you measured. I can imagine that much error using a typical DMM, and this highlights a difficulty in using that method.

[jon]

just as a FYI i measured a 1ohm resistor and it was accurate. But I could see measuring a winding to be a little different.

[Reeltarded]

Jon, you should check that meter with 500 1R 1% resistors in series to get a more accurate idea of wha your meter thinks.

-sips slurpee-

Maybe..