04-12-2013, 10:30 PM
Brenda,
I made a bunch of measurements to be sure I'd told you right about the cathode current. I do have about 22 mA of cathode current even with no plate voltage, but the screen grid is at about 77 volts (spec 100 V.) Could the screen grid be drawing some current from the cathode, even with the plate near zero?
If I can find the time, I'm going to try the output transformer from my RCA radio/phono this weekend. It's a little different, but it's close enough that it should work unless it decides to die like the two others.
I'm afraid my understanding of impedance versus resistance is rudimentary. There doesn't seem to be any rhyme or reason to the impedance specs in the Hammond transformer data sheet. The values are all over the map. How would I know what is the proper primary/secondary impedance to get?
I made a bunch of measurements to be sure I'd told you right about the cathode current. I do have about 22 mA of cathode current even with no plate voltage, but the screen grid is at about 77 volts (spec 100 V.) Could the screen grid be drawing some current from the cathode, even with the plate near zero?
If I can find the time, I'm going to try the output transformer from my RCA radio/phono this weekend. It's a little different, but it's close enough that it should work unless it decides to die like the two others.
I'm afraid my understanding of impedance versus resistance is rudimentary. There doesn't seem to be any rhyme or reason to the impedance specs in the Hammond transformer data sheet. The values are all over the map. How would I know what is the proper primary/secondary impedance to get?
John Honeycutt
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