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Philco 37-10 magnetic tuning problems
#23
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I have found a way to restuff C81, the 0.05 µF tone control capacitor that connects to one of the 6F6G output tube plates.  If you imagine the output transformer to be a seesaw with the centre tap at the rated 250 volts, one tube conducting fully could force the other plate up to 2 x B+.  You might get away with a standard 600 or 630 volt capacitor here but leakage inductance could force the voltage above that and I like to use a generous derating for film capacitors.  I have connected a pair of WIMA box capacitors of 0.1 µF 630 volts each in series to make a 0.05 µF capacitor rated at 1260 volts, reducing the stress on everything.  I have added some tape across the capacitor connections and the 3/16 inch height of the boss plus the thickness of the star washer keeps it well off the chassis.

[Image: https://i.postimg.cc/28sgbTmR/IMG_0656.jpg]


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RE: Philco 37-10 magnetic tuning problems - by amptramp - 09-17-2018, 07:44 PM



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