In my old radio sits a large capacitor next to the rectifier. The radio hums. I have a suspicion that this is must likely causing it. The problem is that it looks special. Not with one value like the others but two values. It has three pins and one is marked red and one marked yellow. On it is written
48uf red outer section
48uf yellow
320/350 v DC
Type EAL
2207 eqi
Is this what is called a dual capacitor and can I replace it with two single 48uf capacitors in parallel?
You can replace it by two regular capcitors. In most cases, both capacitors are not parallel connected, but may be they are in your radio. If they are paralleled, a single 100 µF capacitor can be used as replacement.
You can replace it by two regular capcitors. In most cases, both capacitors are not parallel connected, but may be they are in your radio. If they are paralleled, a single 100 µF capacitor can be used as replacement.
OK, you need two capacitors then. One for red to silver, and one for yellow to silver. If you use electrolytic caps, be careful to get the polarity right. I would guess red and yellow are positive and silver is negative, but it's best to check.
By design of electrolytic capacitors (negative terminal connected to aluminium jacket) dual capacitors have always common negative terminal and are connected in parallel.
Yes, of course the dual capacitor design makes no sense if you only want paralleled capacitors. These devices have been widely used with tube radios, mostly for CRC filtering as you mentioned.
Yes, it's an old tube radio.
I managed to find the company that made the capacitor. Still exists live and well. But they don't have a dual capacitor of the same values any more.