Quote:
Originally Posted by Mrgroovy
Interesting. Does that mean that the one 10uF electrolytic capacitor (the brown-reddish one I have swapped out with a modern type by now) was probably not there in the first place? And if so, were there really no electrolytic capacitors originally installed in this radio?
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There's a good chance that the old 10uf was an original fitment, possibly performing the same circuit function as its replacement is doing now, there were two common methods of implementing an arrangement for obtaining the bias voltage for the valve in mains operated receivers, one way was the use of a resistor (usually bypassed with an electrolytic capacitor) connected in series between the cathode and chassis, the other way was by connecting the cathode directly to chassis and connecting the chassis to the centre tap of the mains transformers HT winding via a low (ish) value resistor, the -ve voltage (with respect to chassis) developed across that resistor would then be used as source for the grid bias voltage.
Lawrence.