Re: [TenTec] Orion II A9 Board Failure...Again!

["Ron Castro" <ronc@sonic.net>]

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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