[Elecraft] Any thoughts about rig LONGEVITY???

[David Woolley (E.L)]

Don Wilhelm wrote:
> 
> Certainly components do have a lifetime - and that is expressed in MTBF 
> - mean time between failures.  For most individual components, that time 

MTBF is not a measure of lifetime, and ALL components have MTBF's.  In 
human terms, MTBF is the non-accidental death rate amongst 25 year olds, 
which does not predict that hardly anyone reaches 110.

> is expressed in hours of power on time - but the lifetime is typically 
> in the range greater than 100,000 hours (11 1/2 years).  Those 

If there are more than a couple of components, other than deliberate 
consumables, that have an MTBF this low, the design has a serious 
reliability problem.  E.g. if you have 500 components with MTBFs of 
100,000 years, you can expect a failure approximately every 200 hours.

> components that fail in a short period of time (usually less than 3 
> months) are not counted in the MTBF figure and are termed early life 
> failures.  Devices that have operated beyond the early life failure 

The failure rate curve that you are referring to is known as the bath 
tub curve, because it rises at both the left and right sides.  The side 
you are referring to is the infant mortality phase, which is often 
covered by warrantees, or by factory burn in.  However there is also an 
old age phase.

In particular, this causes confusion with hard disk drives, as the 
system MTBF implies a useful life comparable with human lifetimes, but 
old age failure actually sets in at around five years.



-- 
David Woolley
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