[Elecraft] REPRISE: As good as it gets...for now?

[David Woolley]

Don Wilhelm wrote:
> <div class="moz-text-flowed" style="font-family: -moz-fixed">Rod,
> 
> If you keep it dry, electronics will store nicely for a good long time.  
> Temperature is not a consideration as long as condensation is 

Although not as significant as when devices are under bias, the 
Arrhenius equations still implies that the failure rate will have an 
exponential dependence on temperature and thermal cycling will still 
cause mechanical stress.  I'd guess that the combination of under bias 
degradation and thermal shock from operation will probably age the 
system more in a few weeks of operation than two years of storage, though.

The other consideration for long storage, although probably not for two 
to three years with modern components, is that eletrolytics will 
depolarize; that can result in excessive currents if there is no natural 
current limitation, until the oxide reforms.  If the current is too 
limited, it may prevent them reforming, which is, I suspect, how the 
electronics in one of my cameras died when I didn't use it for several 
years.

I'd guess a couple of years is OK with modern components, but it would 
be advisable to power it up overnight from time to time if it is going 
to be mothballed for a very long time.  This is the main reason why very 
old equipment, which hasn't been used for a long time, should be treated 
with extreme care, as old electrolytics can explode quite spectacularly 
if their oxide has decayed and they are effectively short circuit. 
Modern ones are  designed to break open before they explode.

Because some power lines are only active on transmit, you may need to 
key the transmitter, at low power, into a dummy load, to ensure that the 
electrolytics are reformed.

> controlled.  If it is at a temperature extreme when put back into 



-- 
David Woolley
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