View Single Post
  #44  
Old 02-06-2022, 05:28 PM
old_tv_nut's Avatar
old_tv_nut old_tv_nut is offline
See yourself on Color TV!
 
Join Date: Jul 2004
Location: Rancho Sahuarita
Posts: 7,754
Quote:
Originally Posted by bandersen View Post
...
There has also been a loud hum since the start of this project. Some of that may be due to this super simple audio coupling design. Just a cap from the volume control to the grid and a 10M resistor to ground. Just bring my hand near that circuit increases the hum.

Wrapping the cap in grounded foil helps a little.
I'm going to recheck the tube to make sure there is no heater cathode leakage.

Did you try reversing the cap? Hum pickup can be different depending on which end is the outer foil.
__________________
www.bretl.com
Old TV literature, New York World's Fair, and other miscellany
Reply With Quote