After consulting via Email with my Georgia electronics engineer friend, I find I misspoke in an earlier reply to your question about the cathode bypass capacitor on the Baby Champ (and other AA5 or AA6 radios). It should be removed as it serves no purpose, except to possibly introduce distortion, once a Zener diode as been substituted for the cathode resistor.
If low-level audio distortion persists when the cathode cap is removed, he suggests I check the value of the plate resistor on the first audio 12SQ7 to make sure it is within tolerance and replace the coupling capacitor from the center of the volume control to the 12SQ7 grid.
I haven’t done any of these things yet as I have other projects going, including customizing some nice old Triplett 3413 emissions tube testers.
- This reply was modified 9 months, 2 weeks ago by Eric Strasen.