The AM Forum

I've always been partial to Sprague Atoms for my jobs but it's been a few years since I needed any and prices just haven't gone up, selection has gone down. AES lists a few different values, most useable if not for size considerations related to voltage rating. I'm looking for 10 & 20uf (plus a little, like 15 & 25-30uf)@ 300-350 volts, theirs are 50 or 500. When I used a 500v version in a clip-mounted position, the clip ended up pinching the cap and causing it to short (yep, Johnny - finally fixing it!).

If memory serves me, there are some really crappy (light blue?) Asian versions out there that are to be avoided. Damned if I can remember which. Been out of it just long enough to forget.

Just curious what you fine folks who are frequent techs use reliably. The chassis these are on is heavy enough that I don't want to remove again anytime soon once it's done.

TNX

Hi Todd .... been a while since we have had a qso .... on electros .... I've had good luck with Illinois caps and any of the con brothers (nichicon, chemicon, etc) lots of others out there I don't know ...73

I'd go with Nichicon, United Chemicon, Panasonic (Masushita) etc and get them with as high a temperature rating as you can afford. The Atoms are boat anchors and are slowly being discontinued. The only people that are buying them are guitar amp builders who think they are better because they are an old design. They have become extremely expensive. I'd shy away from the Chinese stuff of which Illinois Caps are. Unfortunately,  many of the quality manufacturers are not making axial capacitors. The top quality 105 degree C caps are almost all radial capacitors. Panasonic no longer lists axial electrolytics.

Buy your caps from a real distributor like Mouser, Newark or DigiKey etc. They are warranted. Small suppliers sell lots of store branded Chinese caps and their stock is not as fresh. Cheaper is almost always not better.

I have switched to 105 degree Centigrade from Panasonic.  Xicon from Mouser used to be my brand of choice but they have disappeared.  Also be careful to check whether the cap you are looking at is suitable for high ripple service common to most amateur transmitter/amplifier power supplies.  You will find some physically small capacitors with a 105 degree rating but not designed/rated for the internal heat generation that comes with high ripple service.  Most of the spec sheets are pretty good about specifying this attribute.

It is really difficult to avoid Chinese caps now and unless you check closely you may be surprised.  Production is so cheap in China that many brands contract their production to facilities there and I expect the distributors probably don't always properly keep up with CoO (Country of Origin) data.

I have replaced failed Chinese caps in a few semi-modern radios and I note the leaked electrolyte has a different odor and color.  The story I have heard was the "acquired" recipe wasn't complete and a stabilizing agent was left out.  Couple this with the often poor process control and long term results aren't pretty.  Of course if you plan on a 5 year life (apparently market acceptable for most consumer products, just not to us) then the Chinese caps are fine.

Do you have a source for axial leaded Panasonics? I used to get them from DigiKey but can't find them available anywhere.

Pat

Pat,

I last ordered a batch from Mouser but that was about a year ago. I just checked and they stock nothing but radial style from Panasonic and Allied is the same.  It looks like Panasonic has gotten out of the axial lead type. 

Rats!  Now I have to find a new favorite brand.  There are many times where radial leads just aren't a good fit.

Sounds like you are rebuilding a receiver?  I've used Illinois caps rated at 500v in lots of receivers and low power audio amps and not had a failure. 

I would echo the advise about buying from a major supplier.  My first scratch built audio amp used caps from a small supplier; and both power supply caps exploded in spectular fashion when I applied power.  Didn't even blow the fuse! 

73 Alex

Hi All,

Considering the voltages involved with hollow state gear, would it serve any purpose to form the cap with a power supply (slowly) before pressing it into service?

RSWL..................

I like the F&T caps made in Germany for my more "critical" applications.

I have used the JJ caps for lower temp environments and have had not problems with them.

Phil - AC0OB  (The "other" Phil   :D)

I looked around last night and could find no axial caps rated higher than 80 degree C. Many radials though.

Forming is not at all necessary for new electrolytic capacitors in my opinion. With old caps it is useful, although I don't use NOS electrolytic caps if at all possible. Just my personal opinion and I have never had an electrolytic cab blow up (that is if I had it wired correctly).

We used to take the little epoxy covered orange electrolytic caps from Southwest Technical Products in the late 60s and hook them up  reverse polarity and blow them up. They popped like a small firecracker and sent a spiral of paper out the end like confetti. I hate to think how many we destroyed for fireworks.

Pat

I second the F&T German caps for electrolytics, and Solen non-electrolytic for most everything are really excellent.

I get them both from AES in Tempe.

73DG

Todd,
I have used Newark Electronics over the past with good results.  They have a pretty good search engine. 

I have used various brands but probably most were made by CD.  They have a nice selection of 105C parts which I always use. 

Joe - GMS

http://www.newark.com/jsp/search/browse.jsp?N=422+2203+217007+810029809+810064356+810029838+810000008+810085544+810072474+810014741+810070309+810048962+810073904+810078057+810108559+810014739&Ntk=gensearch&Ntt=axial+electrolytic+High+voltage+105C+capacitors&Ntx=mode+matchallpartial&No=0&getResults=true&appliedparametrics=true&locale=en_US&divisionLocale=en_US&catalogId=&skipManufacturer=false&skipParametricAttributeId=&prevNValues=422+2203+217007&mm=1000360|810029809|,1000002|810085544|810014739,&filtersHidden=false&appliedHidden=false&autoApply=false&originalQueryURL=%2Fjsp%2Fsearch%2Fbrowse.jsp%3FN%3D422%2B2203%2B217007%26Ntk%3Dgensearch%26Ntt%3Daxial%2Belectrolytic%2BHigh%2Bvoltage%2B105C%2Bcapacitors%26Ntx%3Dmode%2Bmatchallpartial%26No%3D0%26getResults%3Dtrue%26appliedparametrics%3Dtrue%26locale%3Den_US%26divisionLocale%3Den_US%26catalogId%3D%26skipManufacturer%3Dfalse%26skipParametricAttributeId%3D%26prevNValues%3D422%2B2203%2B217007

Problem is, all of the above in the search are 85 degrees C or less. The only 105 degree C ones at Newark are radial leaded.The max operating temperature is what you are looking for  - not hours life at 105 degrees C.

Most of the axial one listed are Chinese - Multicomp or Illinois. The Vishay ones have a $20 shipping charge from Farnell and the Cornell Dubliers one are priced at $25 each or more - and again they are all 85 degree rated. I have purchased the Multicomps in 10uF and 22uF 450 volt  from Newark and am not impressed with them. They are very low cost though.

As shown in the list I posted, some of the Multicomp brand are axial and are rated at 105C.  I have used those with good success.

Joe, GMS      

Here is a link to the Solen line at AES;

http://www.tubesandmore.com/products/C-FS-630

For instance, a 22uf @ 630V is under $10, that is for a lifetime cap.

I have put them in all my pre-war Super-Pro restorations, and am glad I wont have to do it again.  Restuffing those old can caps is a lot of bother, but the right 'look' is worth it on a historic radio.

Here is a link to a type of F&P electrolytic, and I use these in gear that is not so 'sensitive' to scrutiny:

http://www.tubesandmore.com/products/C-EC16-16-450FT

Top quality, nonetheless, better than anything From Asia.

73DG

Not trying to argue - but when I follow  that link - every cap in it is rated at 85 degrees C max operating temperature or lower - two Multicomps have a life rating measured at 105 degrees C but are maximum temperature rated at 85 degrees C.

Do your search with radial caps and there are quite a few radials rated at 105 degree max operating temperature.

I have not found any axial electrolytic caps that are rated at 105 degree C at any supplier lately except MIEC in Taiwan. These are the people who make the store branded caps from Mojo, Webber, Just Radios etc. They have a poor reputation for longivity which is common with many low cost Chinese brands.