[Premium-Rx] Cubic R 2411/R 3030 blows caps

[Mark Donaldson]

Try replacing them with electrolytics, Tantalums have
this wierd property where for a brief instant upon
application of voltage they will present a very low
impedance, so low in fact that they can weld
themselves short circuit if there is not sufficient
current limiting on the supply line, electrolytics do
not exhibit this characteristic. Once these tantalums
weld themselves into a short circuit they sit there on
the PCB board and procede to burn a hole through it if
there is nothing to limit current. I have worked at
two companies so far that have eliminated tantalums
from their products for this reason. Unfortunately
electrolytics are limited on their low end operating
temperature range due to electrolyte freezing thus the
reason tantalums are used.

Mark Donaldson WA1QHQ

--- "Royce, Alan (Space Technology)"
<alan.royce at ngc.com> wrote:

> Hi, 
> Got a R 2411 that blows the 35 volt 10u tantalums
> when you power it up.
>  Caps/tantrums, are located at the input to the plus
> and minus to the 16
> volt line to each of the modules on the left side
> radio.
> I have looked at the 16 volt lines and can not see
> any spikes on them.
> I have al ready replaced at least 10 tantalums, even
> now replacing the
> ones that I replaced before.
> Any one have a clue to what is going on??
> Thanks 
> Al
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