I am replacing the capacitors in the two cans on my Philco 46-1209 radio. The cans are now empty and I am having a difficult time finding the caps of the right specs that will fit inside the cans. The first can needs a 20mfd 450vdc cap. The can id. is .940" and the length is 1.70". I would prefer a radial cap but I believe that there is room for an axial. The second can uses a 10mfd 450vdc and a 25mfd 450vdc cap. The can id. is 1.32" and the length is 1.62". Again, I would prefer radial caps but axials or a mix of both are ok as long as they fit in the cans. The cap that I am having the most trouble finding is the 25mfd 450vdc in a radial form. I see a lot of 22mfd vdc but no 25mfd 450vdc radial. Does anyone know where I can find these? Will the 22mfd be ok for replacement of the 25mfd? [
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Hello Patrick and welcome to the Phorum. First off you must be careful to provide good data so we can evaluate your specific situation. I had to decide if you are working on a 46-1209 or a 46-2019. Since I couldn't find anything on a 46-2019 I'm assuming it's the 1209. Looking at the schematic, the 22mfd should work. I get most of my caps from Mouser Electronics. They have physical size options for your stuffing and you can get your small parts order shipped for 4.50. My order came in a few days last week.
Thank you for your reply. I previewed the post but missed the 2019 mistake and have since edited it out. I'll check with Mouser. I usually use digilink. If Mouser has the 25mfd i'll check with them for the others to keep it in one order. If so I should be in good shape. Thanks again!
I use this series of slim/tall caps. Most of them have a ripple current rating of 500ma or better. In this case they were still too wide to fit, but if they had fit, I would not have had a picture for you
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Yes, thank you. I noticed and am considering them.
Ditto what Phlogiston said.
I use 22uF 450V, or for 10uF same in series.
And, the main rule is: the only cap that should be close or the same value to the shown in the sch is the very first one after the rectifier tube. (22uF is just fine for 25uF, for instance).
The rest of the caps could be larger values without much effect. Of course if a cap is 20uF, one could use 47uF, but I would not recommend going to a 470uF or 1000uF (which I recently found in a couple of my radios that someone repaired in the past).
And, also, as Phlogiston mentioned, the very first cap should have a decent ripple rating and should not be a GP cap. If, of course, you cannot fit a film one in there.
Serialized caps of the working voltage close to the actual voltage do not require leakage equalization with resistors. If however the WV of the serialized caps is just over half of the actual voltage, then the resistors are recommended as otherwise a voltage across one cap could exceed the WV rating.
So then it would be ok to use the 22uF to replace the 20uF and the 25uF both in different electrolytic cap cans? It would make it a lot simpler for the order and stock. The Nichicon 22uF comes in several small diameter packages to meet my can size requirements.
When you consider electrolytic caps in power supply filters there's a wide tolerance except for the first one at the cathode. For that one it's best to match as close as possible so you don't damage the rectifier. Most tube manuals will have the maximum input filter capacity listed for power rectifiers. You're right about the 22mfd, I find it cheaper to order a quantity of ten and get the price break. I probably use 47 and 22 more than any other values.
Thank you, sir. I will keep that in mind when selecting capacitors.