14-04-2020, 04:08 PM
One step forward, and one back.
Mains lead replaced, incorporating a mains earth on the chassis. I have no concerns about the mains transformer insulation being up to scratch, I want it earthed, if the transformer goes bad I will fix it. The QMB switch only breaks the live.
With new smoothers fitted, still got a 50Hz hum, Changes with volume. It ceases when the volume control is at maximum against the stop.
Its either picking up somewhere or its a valve heater cathode leak. It will take a bit of detective work.
Found out why the shortwave is deaf, the oscillator coil core has broken in half at the end of the brass adjuster. I've removed the bits and epoxy glue seems to have repaired it. Will see tomorrow when its set and refitted.
The tuning gang has been restrung, therein lies an anomaly. Turning the tuning spindle produces bad crackles, but turning the gang capacitor by hand does not. Never found this before. I will try a bronze leaf spring on the end of the spindle under the chassis to ground it properly.
The oscillator tracking on medium and long is very good, station locations agree with the dial markings.
Extracted the bayonet bulb and fitted a proper 6.3V 0.3A MES one, seems a waste of time really as they don't light the dial very well at all.
Mains lead replaced, incorporating a mains earth on the chassis. I have no concerns about the mains transformer insulation being up to scratch, I want it earthed, if the transformer goes bad I will fix it. The QMB switch only breaks the live.
With new smoothers fitted, still got a 50Hz hum, Changes with volume. It ceases when the volume control is at maximum against the stop.
Its either picking up somewhere or its a valve heater cathode leak. It will take a bit of detective work.
Found out why the shortwave is deaf, the oscillator coil core has broken in half at the end of the brass adjuster. I've removed the bits and epoxy glue seems to have repaired it. Will see tomorrow when its set and refitted.
The tuning gang has been restrung, therein lies an anomaly. Turning the tuning spindle produces bad crackles, but turning the gang capacitor by hand does not. Never found this before. I will try a bronze leaf spring on the end of the spindle under the chassis to ground it properly.
The oscillator tracking on medium and long is very good, station locations agree with the dial markings.
Extracted the bayonet bulb and fitted a proper 6.3V 0.3A MES one, seems a waste of time really as they don't light the dial very well at all.
Boater Sam.
