UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Aga Baltic AH37. Need help identifying old capacitor from 1930s radio

PJL · 7th Oct 2018, 8:43 pm

There is no assurance that the AL1 modification ever worked properly. If we could find a circuit diagram we could at least see what has been changed but it seems this is very unlikely. It would be helpful to see how the other valves are wired.

Based on the circuit by George, I would say it is wired incorrectly. The reservoir and smoothing capacitors should go to chassis and the centre tap should go to the 500 ohms. A resistor and capacitor smoothing would then be taken off the centre tap to provide the grid bias. The wiring for the other valves may give a further clue as they may also have -ve grid bias.

7th Oct 2018, 8:43 pm	#45
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Need help identifying old capacitor from 1930s radio There is no assurance that the AL1 modification ever worked properly. If we could find a circuit diagram we could at least see what has been changed but it seems this is very unlikely. It would be helpful to see how the other valves are wired. Based on the circuit by George, I would say it is wired incorrectly. The reservoir and smoothing capacitors should go to chassis and the centre tap should go to the 500 ohms. A resistor and capacitor smoothing would then be taken off the centre tap to provide the grid bias. The wiring for the other valves may give a further clue as they may also have -ve grid bias. Last edited by PJL; 7th Oct 2018 at 8:49 pm.