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ronbryan · 17th Nov 2019, 3:45 pm

I think the difference between BD244U and BD254U is just in the detail of the UL41 output valve tone control stage. The 244U has a single 470pF capacitor in the negative feedback between anode and tone control, the 254U has a 'T' network of two series capacitors and a resistor to ground. My 244U seems to have been manufactured with the 254U tone control circuit anyway.

Problems that I am aware of include a burnt out 10k screen grid resistor to the UCH81, leaking ERO paper capacitors and background hum. The 100uF + 50uF smoothing capacitor may need replacing to reduce ripple on the HT and the three terminal (screened) audio coupling caps can be replicated by fitting earthed copper slug tape around the replacement axial component.

I choose to run my set on a 220V AC supply to reduce the heat build-up in the small cabinet, as there is no 240V option.

Good luck with the postal system - it can result in the chassis breaking away from the bakelite fixing pillars in the cabinet.

Ron

17th Nov 2019, 3:45 pm	#4
ronbryan Octode Join Date: Jan 2003 Location: Guildford, Surrey, UK. Posts: 1,960	Re: Philetta BD 244U I think the difference between BD244U and BD254U is just in the detail of the UL41 output valve tone control stage. The 244U has a single 470pF capacitor in the negative feedback between anode and tone control, the 254U has a 'T' network of two series capacitors and a resistor to ground. My 244U seems to have been manufactured with the 254U tone control circuit anyway. Problems that I am aware of include a burnt out 10k screen grid resistor to the UCH81, leaking ERO paper capacitors and background hum. The 100uF + 50uF smoothing capacitor may need replacing to reduce ripple on the HT and the three terminal (screened) audio coupling caps can be replicated by fitting earthed copper slug tape around the replacement axial component. I choose to run my set on a 220V AC supply to reduce the heat build-up in the small cabinet, as there is no 240V option. Good luck with the postal system - it can result in the chassis breaking away from the bakelite fixing pillars in the cabinet. Ron Last edited by ronbryan; 17th Nov 2019 at 3:52 pm.