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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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16th Jun 2020, 10:20 am | #21 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Ducretet Thomson L524
Sorry Chris I did notice your last post can I replace c23= 40nf with 0.047uF 1000V Polypropylene Axial Capacitor I cant find what to replace c24 = 10nf with you say y class and what voltage for this one. Found this one 250vac
Thanks mark Last edited by rockinmark; 16th Jun 2020 at 10:43 am. |
16th Jun 2020, 11:57 am | #22 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
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Re: Ducretet Thomson L524
The cap pictured is the correct spec but is one of the notorious Rifa stink bombs
Unless it's brand new (in which case it'll probably be OK for ten years or so). I'd go for something like this: https://uk.farnell.com/epcos/b32022a...22?ost=1609522 C23- 40nF seems excessively large. 4nF would be more reasonable. Is the actual capacitor really 40nF? I'd probably try something like 2.2nF.
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16th Jun 2020, 12:53 pm | #23 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Ducretet Thomson L524
Thanks for that Chris i will get that one I as for c23 is so bad it hasn't got any markings on it but i was going by the schematic
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16th Jun 2020, 2:18 pm | #24 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
Posts: 594
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Re: Ducretet Thomson L524
Presumably 630v will be OK for that
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16th Jun 2020, 2:53 pm | #25 |
Heptode
Join Date: Sep 2014
Location: St Albans, Hertfordshire, UK.
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Re: Ducretet Thomson L524
Here is picture of l524 and l624 everything seEms the same but that one capacitor and I don't know why its 40nf unless it's a mistake.
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16th Jun 2020, 9:11 pm | #26 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,535
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Re: Ducretet Thomson L524
I'd stay with 1000V for the C23.
Value wise, even the 624 has 10nF which still seems rather high. A quick simulate suggests that 40nF will have the treble response down by 3dB at 1kHz. That's going to sound very woolly. 10nF moves the -3dB point out to 4kHz which is still going to cut what little treble there is in an AM signal somewhat. Admittedly '40s / '50s tastes did run to "mellow" sound but like the DAC90A I suspect some more brightness would suit nowadays. I'll stick with my 4.7nF suggestion. You could just add another in parallel if it sounds too bright!
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