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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 10th May 2021, 8:05 pm   #181
ms660
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Default Re: EKCO U122 - Restore or spares?

Exceeding the maximum reservoir capacitance for the given surge limiting resistance means that the surge limiting resistance should be increased, some valve data doesn't say that but some do, eg:

https://frank.pocnet.net/sheets/049/5/5Y3GT.pdf

I did come across a schematic (forgotten which) using a UY41, the reservoir capacitance was 70uF and I think the surge limiter was at least 400 Ohms, possibly 500 Ohms.

Lawrence.

Last edited by ms660; 10th May 2021 at 8:14 pm. Reason: extra info
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Old 11th May 2021, 10:11 am   #182
Gabe001
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Default Re: EKCO U122 - Restore or spares?

Donald, why don't you start by increasing the smoothing and reservoir caps from 16/32 to the values specified for the uy41 on the valve specifications document ie 25/50? Also the uy41 document recommends a 0.022uf cap in parallel to reduce hum.
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