Hello ! Would anyone know if the 2 mfd caps within the multi-section "B" block are polarized or non-polar ? Could I sub a polarized electrolytic ?
Also- is it normal for all these old tubular caps to appear to increase their value dramatically ? I'm seeing .015's that read like .06 mfd . makes me think I have the wrong info, but no....
Welcome to the Phorum!
I moved your thread into the Electronic restoration section.
Thry are non-polarized.
It is typical for them to increase in value when aged. Yes 0.015 uF will easily become a few times that.
Electrolytic are fine.
Better yet, use modern film caps like Solen, they will last forever whereas lytics are inherently limited life parts.
Hi and welcome,
As Mike mentioned the better choice is to use film caps for the power supply filters. I serviced a Philco 87 which has a similar style power supply and use several pair of 4.7mf @450v electrolytics in series to equal abt 2.3mfd. All went well but after abt 6 months of uses the input filter shorted and nearly took out the 80 rectifier tube. Wouldn't use ecaps in these late '20 and early '30s sets.
Well,
To exonerate the electrolytics a bit I need to state that most times a lytic cap from a reputable mfr, properly sized WV and ripple current-wise (the latter is mportant) will do just fine and will die slowly as most lytics do over a period of many years.
This said, if fit size-wise, the film caps will last forever. In terms of human lifespan.
Thank you all ! Are the films non-polar? I'm not familiar with these- does anyone know a good source for small quantities? i often buy from Antique Electronic Supply(Tubes and More) I'll try to look them up. This old 95 highboy is really quite well preserved; it definitely needs to work well. Cabinet and pictorial grill cloth are excellent.
I mostly get caps from Sal's
http://www.tuberadios.com/capacitors/ Prices are good and you can get singles although I usually buy in quantity as I'm always am working on something.
Yes film cap are non polarized (no + or -). You can parallel up several to get the specified value.
The model 95 is a 1929 model, so no electrolytics were used, though the wet Mershon electrolytics were available at the time I think. A.E.S carries the Solen brand film caps, which have a good reputation, I think that they are also offered in values up to 15 uf but don't quote me on that. For the 2 uf sizes you can probably use those yellow 630 Vdc caps with no issue.
Regards
Arran
Thanks!! That really helps.
Thank you !! really helpful !
I am curious, with all the discussion about ripple current and electrolytics, how does one determine how much ripple current there is in a power supply? In other words, how do you determine when a cap has sufficient capability to work in a particular application? I know you can use Solens or metal film caps and be good.
Ron
The rule of a thumb often is to make the ripple rating equal twice the load current. That only goes for the very first cap (paralleling the rectifier tube). He rest do not see as much ripple.
So if the rectifier supplies the radio with 50mA of current, the 100mA rating is enough.
I use higher rating so I do not have to think about it. I buy Panasonic caps that are about 600mA rated and this is good for just about any rectifier, even in the Eico stereo amp.
I have a box of capacitors from:
https://justradios.com/
Prices are reasonable because he is a Canadian supplier in the Scarborough (east) side of Toronto. Dave Cantelon is a member of the London Vintage Radio Club, which is where I met him. One of the good guys and he has X1 and Y2 capacitors for AC line input use.
Thanks Mike, that makes it easy enough!
Ron