05-25-2020, 07:53 PM
Today I refitted the push buttons and coil set for the MW presets. This was a bit fiddly, as it was necessary to replace the 12 rather heavy gauge wires that link the two assemblies. The other connecting wires were returned to the appropriate tabs. I was very confused when powering up to test - all bands were receiving a steady level of noise, with no tunable signals at all. The IF was working but nothing getting through from the mixer. Oscillator working just fine, voltages checked.
Eventuially I found the trouble, just before I had resigned myself to removing the preset components again. The frame for the pushbuttons was just touching the 2 meg resistor that feeds AVC voltage to the signal grid of the 6A8. All the incoming signals were being shorted out! That was easy to fix, and the chassis is electrically complete again. All the presets tuned up to stations and work well.
Cheers
Ed
Eventuially I found the trouble, just before I had resigned myself to removing the preset components again. The frame for the pushbuttons was just touching the 2 meg resistor that feeds AVC voltage to the signal grid of the 6A8. All the incoming signals were being shorted out! That was easy to fix, and the chassis is electrically complete again. All the presets tuned up to stations and work well.
Cheers
Ed
I don't hold with furniture that talks.