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Electrolytic? - 1230AM - 02-27-2020

Quick question - I have a cardboard capacitor in my 47-1230, .05mfd, 600v.  Its yellow and has a black stripe circling one end, but nothing indicating that end to be of any polarity.

Does the single stripe in and of itself indicate the negative end, and hence an electrolytic, or is it merely part of the branding by the makers of the of the capacitor?  Cap says Universal on it, looks like a brand name.  Nothing within the stripe or any other polarity indicator.

Radio still has low volume and this looks like final obvious cap, although I have seven that are very small, bout as big around as a large knitting needle and maybe 3/4 inch long that say 100mf on them - that's it.  I'm guessing those need to be replaced as well?

Thanks

RE: Electrolytic? - Radioroslyn - 02-27-2020

> negative end, and hence an electrolytic
Nope foil paper cap. E caps most of the time 1mf or larger. The line on one end tells which end has the outside of the foil connected to it.
>that say 100mf on them
Kinda doubt it that's an awful lot of mf's for such a small package. Reread value.

RE: Electrolytic? - 1230AM - 02-27-2020

You're right on the little ones are 100mmf, meaning I replace with .0001mf if I'm reading the conversion chart correctly, right?  There's a couple in the picture.

Large one is actually ceramic.  Still unclear if electrolytic.  Small value but the line is throwing me..

RE: Electrolytic? - rfeenstra - 02-27-2020

NOT electrolytic.  It is a standard paper/foil capacitor.  The line, as said previously, indicates the connection that is connected to the foil that is on the outside of the rolled foil/paper.  This end of the capacitor is normally connected to the lower impedance to ground in the circuit.  By doing that, the outside foil acts as a shield for the higher impedance side of the circuit, thus reducing the chance of outside interference (hum.)

RE: Electrolytic? - RodB - 02-27-2020

The line around one end of a paper capacitor indicates the lead wire that's connected to the outside foil of the capacitor. This lead is typically connected to the lowest impedance side of the circuit to reduce outside interference. Some capacitors will have "outside foil" in place of the line. Electrolytics will almost always be marked "+" & "-" to show positive and negative.

Rod

RE: Electrolytic? - 1230AM - 02-27-2020

Thank you Rod.   The first response included parts of my original question - which I read as an answer, and for someone new looking for clarity was again, as stated above, unclear.

Can you confirm my calculation re: the 100mmf replacements?  .0001mf correct?  Smallest I've found is .0005mf.

Thanks

RE: Electrolytic? - Radioroslyn - 02-27-2020

Yup .0001=100mmfd or uufd. I wouldn't fool with smaller than .005. You want to focus in on foil/paper and the ecaps. The micas and ceramic leave alone.

RE: Electrolytic? - rfeenstra - 02-27-2020

you are correct.  go to the following link for a conversion chart:

https://www.justradios.com/MFMMFD.html

They are good source for capacitors.  You may have to go to a Silver Mica capacitor to get the 100mmf (.0001mf, .1 nf, 100 pf  -  confusing, right?!).

RE: Electrolytic? - mikethedruid - 02-27-2020

This whole nano-farad thing is an innovation in terminology of the past decade or so. We always used to use just micro-farad, and micro-micro farad, which some innovative fool decided to rename pico-farad in the late 1960s. This latest, nano-farad, is one of those innovations which some other fool came up with to justify their existence, and which was not really needed. I think part of it is that these new digital displays on a lot of meters are only 3 1/2 digits, and couldn't deal with the span between mfd and mmfd, and so they stuck in nf between them because it was cheaper than adding more digits to the displays. So now, instead of just converting between mfd and mmfd like we used to, and which most of us could do in our heads by now, we have to convert between 3 different ranges. What a pain in the a&&.

RE: Electrolytic? - RodB - 02-27-2020

I'm working on a 1960 German made Grundig right now and all the tiny capacitors on the schematic are in "pf". Evidently pico or pf doesn't translate to German.

Rod

RE: Electrolytic? - Radioroslyn - 02-27-2020

+1 Mike
Back in the day we just had to know fractional numbers and an occasional decimal number now it's decimal metric/inch, fractional, liters,kilometers ect.... Makes me a little nutz sorting it out sometimes.

RE: Electrolytic? - 1230AM - 02-28-2020

Thanks to you all!! It is kinda confusing but with your help I think I can get there. Fun hobby, I like old stuff, and these old radios are just cool. Gotta tackle schematics. No matter what I try to read and figure out it still looks like a bunch of lines.... I think local club is the key.

Until I get stuck again - which may not be too long...

Thanks again.