[MrFixr55]

Hi RGK,

Consider adding an Aux input not only for extra enjoyment but also for "divide and conquer troubleshooting. Does the issue also occur with an external audio signal?

Is the AVC voltage a negative voltage? does it change at all from station to station? The bias for the convertor and IF come from 2 sources. There is a fixed bias from the voltage divider from chassis ground to the center tap of the HV winding on the power supply (common way of getting bias in pre-war radios. The variable bias (AVC) comes from the plate of the 6J5. How they use the 6J5 is quite clever. They are not quite using it as a triode. They use the grid as the plate for the detector diode. They use the plate as the plate of the AVC diode. The 100pF cap #23 supplies the output of the IF to the AVC plate. The 0.05uF cap #3 filters the DC voltage created by AVC. Check these caps and the 1Meg resistors #27 and #15. Consider just replacing these components. The 100 pF caps are mica. Most folks believe that these don't fail but sometimes they do. Not as commonly as a paper-foil cap but once in a while they fail.

In addition, consider heating all the solder connections, cleaning and tightening tube socket pins. Based on the statement that the volume changes when you attempt to make voltage measurements, you may have a cold joint. You may also consider replacing resistors 10, 12, 15 and 27, and Caps 11, and 14. these caps and resistors supply B+ to several parts of the radio's RF and IF section including screen grids. If the screen grid voltage changes, output changes. Resistors may have checked OK and solder joints may look good, but the radio IS 88 years old, and these parts may check OK at static low voltages but fail when current is drawn.

Hope this helps.