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1-10 of 17 messages
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Which Electrolytics?
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by N4NYY on October 18, 2009
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I have been recapping with general purpose Xicon and Nichicons from Mouser. These are the cheapo general purpose. So far, I have not blown anything up and had any fail. I was just curious to see what kinds people use here. I seem to see that a few brands are ibscenely expensive, like Vishay Spraque.
If available, I use the 105 degree as a first choice with tube rigs. If not, I stick with the 85 degree.
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RE: Which Electrolytics?
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by AD5X on October 19, 2009
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I've been using those same inexpensive electrolytics from Mouser in my boat-anchor re-builds for years. Never any problems.
Phil - AD5X
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RE: Which Electrolytics?
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by AD5X on October 19, 2009
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I've been using those same inexpensive electrolytics from Mouser in my boat-anchor re-builds for years. Never any problems.
Phil - AD5X
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RE: Which Electrolytics?
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by W8JI on October 19, 2009
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I only recap the parts that are bad. That generally means most parts can stay.
When I do change a cap I use an off the shelf from Mouser or Digikey and never have had any problems even with 85C parts. 85C parts are 185F, and that is not the actual limit. Few of my radios will boil coffee under the chassis. If they did, they would be hopelessly ruined from baking the wiring and stuff.
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RE: Which Electrolytics?
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by W8JI on October 19, 2009
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I only recap the parts that are bad. That generally means most parts can stay.
When I do change a cap I use an off the shelf from Mouser or Digikey and never have had any problems even with 85C parts. 85C parts are 185F, and that is not the actual limit. Few of my radios will boil coffee under the chassis. If they did, they would be hopelessly ruined from baking the wiring and stuff.
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RE: Which Electrolytics?
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by WA6HDZ on October 19, 2009
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Any of these modern electrolytics, even the 85C types, are better quality than the ones used originally in many tube rigs. Don't worry. There are some high priced brands catering to the audiophile crowd but you won't need to use them unless you're replacing something very specific like a multi-section metal-can type.
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RE: Which Electrolytics?
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by WA6HDZ on October 19, 2009
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Any of these modern electrolytics, even the 85C types, are better quality than the ones used originally in many tube rigs. Don't worry. There are some high priced brands catering to the audiophile crowd but you won't need to use them unless you're replacing something very specific like a multi-section metal-can type.
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RE: Which Electrolytics?
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by N4NYY on October 20, 2009
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"There are some high priced brands catering to the audiophile crowd but you won't need to use them unless you're replacing something very specific like a multi-section metal-can type."
Speaking of which, I have replaced the multi-sections cans with individual caps. But most are supply caps, and not in the audio chain.
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RE: Which Electrolytics?
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by WX7G on October 20, 2009
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It depends on the model of Xicon or Nichicon. Some types are 'miniature' and have higher ESR and lower ripple current ratings. These can self-heat more in a high ripple current application. The ripple current rating is often defined for a 10 deg C self-heating rise.
Some caps are larger and have lower ESR and consequently higher ripple current ratings. When possible I choose electrolytic caps with a 20 or 30% voltage margin. In some applications the design demands that caps be used at the rated voltage. Some tube amps fall into this category. The manufacturer could have derated the caps by using, for example, six in series rather than five and increased the cap values to compensate. But this requires 44% more cap for the same capacitance.
The reason for using 105 deg caps in lower temperature applications is increased life. Generally 4X more life. From 105 to 70 deg C cap life is said to double for every 10 deg decrease. Below 75 deg it goes in 15 deg increments. Take a 2000 hour, 105 deg C cap for example:
105 deg C 2000 hours
95 deg C 4000 hours
85 deg C 8000 hours (1 year)
75 deg C 16000 hours (2 years)
60 deg C 32000 hours (4 years)
45 deg C 64000 hours (8 years)
30 deg C 128000 hours (16 years)
The wearout mechanism is the loss of electrolyte by evaporation. The larger diameter caps have a greater volume-to-seal area ratio and dry out more slowly.
Capacitor end-of-life life is generally defined as an X% drop in capacitance and a Y% increase in ESR (equivalent series resistance). If proper circuit operation does not depend heavily on the capacitance or the ESR the caps can last for a very long time.
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RE: Which Electrolytics?
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by WA6HDZ on October 20, 2009
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To clarify a bit, I've used high end UK-made LCR-brand caps in a couple power supply rebuilds because there was no room for individual caps without seriously hacking the existing layout. Most of the US brands moved their production to Mexico and China and I was getting the LCR's quite a bit cheaper than they sell for now. I wouldn't be worried about using the cheap caps for cathode bypass or other low ripple energy applications.
Also, I really believe newer electrolytics have better seals than some of the older ones. US manufacturers cheapened the product to cut costs in the late 60's/early 70's. This coincided with the period when Japanese suppliers were improving the quality of their parts.
I notice this a lot in Heath, Hallicrafters, and other brands that were designed around consumer grade components, not so much in Drake, Collins, Hammarlund, etc. that were built with higher quality parts. Your opinions may differ.
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