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Silicon · 18th Aug 2019, 12:06 am

The steady rise of the HT voltage to 108V and then the slow rise over twenty minutes to 170V is something that could be investigated.

It suggests either that something in the power supply is providing more voltage/current, or that something in the radio is initially taking too much current and dragging the voltage down but this lessens with time.

Do any of the valves have a purple glow inside them?

There could be a bad contact in the valve holder of V7. What is the AC voltage at the heater pins of the rectifier valve?

I would still like to know the voltage across, and the current through resistors R30, R29 and R25.

18th Aug 2019, 12:06 am	#14
Silicon Nonode Join Date: Jun 2007 Location: Coulsdon, London, UK. Posts: 2,167	Re: Bush SUG26 The steady rise of the HT voltage to 108V and then the slow rise over twenty minutes to 170V is something that could be investigated. It suggests either that something in the power supply is providing more voltage/current, or that something in the radio is initially taking too much current and dragging the voltage down but this lessens with time. Do any of the valves have a purple glow inside them? There could be a bad contact in the valve holder of V7. What is the AC voltage at the heater pins of the rectifier valve? I would still like to know the voltage across, and the current through resistors R30, R29 and R25.