I hope it will run more than 2,000 hours too! According to Hank, that
number gets multiplied by a factor for lower temp, in this case 1.7 for 80
degree C operation (it's actually much cooler than that), times a factor for
running at lower voltage, which is something like 22 x. If I got that
right, that's 74,800 hours, or 8.5 years of continuous operation, plus the
factor for an ambient temp of around 50 C instead of 80. I think there is
an additional factor for running less than the max specified ripple current.
According to the specs, dissipation, shown as "TAN (lower case Greek
'Delta') at 20 C 120 Hz", is 0.10 for the 50 WV units. I don't know what
that means, but it sounds better than the 0.16 speced for the 16 WV units.
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
To: <tentec@contesting.com>
Sent: Wednesday, June 25, 2008 3:34 PM
Subject: Re: [TenTec] Orion II A9 Board Failure...Again!
> On Wed, 2008-06-25 at 10:36 -0700, Ron Castro wrote:
>> Whoops... that last link was:
>>
>> http://n6ie.com/A9_Fix.html
>>
>> Ron N6IE
>> www.N6IE.com
>>
>>
>> ----- Original Message -----
>> From: "Ron Castro" <ronc@sonic.net>
>> To: "Ten Tec List" <tentec@contesting.com>
>> Sent: Wednesday, June 25, 2008 10:35 AM
>> Subject: [TenTec] Orion II A9 Board Failure...Again!
>>
>>
>> > Hank: Excellent analysis! Can I please link to that from my page?
>> >
>> > I believe, based on this link that there is a direct connection between
>> > ESR
>> > and ripple ratings:
>> >
>> > http://wiki.xtronics.com/index.php/Capacitors_and_ESR
>> >
>> > "Ripple Current Rating
>> > The ripple current is sometimes rated for a capacitor in RMS current.
>> > Remembering that P = I2R where R in this case is ESR it is plain to see
>> > that
>> > this is a power dispassion rating. "
>
> Almost but it doesn't give a number for the heat transfer capability of
> the package. That is vitally important, the larger the case, the better
> that heat will be transfered to the air and environment and that is
> CRUCIAL for keeping the capacitor temperature in reason.
>> >
>> > Here is a link to the data sheet of the caps I used:
>> >
>> > http://www.mouser.com/catalog/specsheets/esrl.pdf
>> >
>> > I haven't figured out the calculations, but the ripple rating is 1355
>> > ma
>> > @
>> > 100 kHz, 50 Volts, 105 C and a "life test" rating of 2,000 hours. What
>> > kind
>> > of life could I expect in the C6 application?
>
> 2000 hours is only a quarter of a year. I want my radio to run longer
> than that!
>> >
>> > BTW, I didn't test the caps I removed, but as you can see if you look
>> > carefully on the 'before' picture on my site, C9 has a bulge on the top
>> > of
>> > its casing.
>
> A bulge is a sign of getting hot and expanding the liquid, possibly by
> boiling it to steam. There are weak points in the case, sometimes that
> leaking electrolyte eats traces from the board nearby.
>
>> TT never told me which caps they replaced the first time
>> > around. Another interesting thing is that all three original caps were
>> > the
>> > same specs, but all three were different sizes.
>> >
>> > http://n6ie.com/A9_Fix.
>> >
>> > Ron N6IE
>> > www.N6IE.com
>> >
> 73, Jerry, K0CQ
>
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>
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