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Re: [Amps] Good engineering

To: "Roger" <sub1@rogerhalstead.com>, "Paul Decker" <kg7hf@comcast.net>
Subject: Re: [Amps] Good engineering
From: "David Cutter" <d.cutter@ntlworld.com>
Date: Sun, 28 Mar 2010 12:22:02 +0100
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Some semiconductors I worked with years ago were rated for 25 years 
continuous operation at maximum temperature.  It was said that the tracks 
inside the part migrated to the next nearest track over time and stress.

David
G3UNA

>
>
> Paul Decker wrote:
>> Definately the wrong attitude, but everything designed has a lifespan. 
>> Bridges, fire suppression systems and airplanes require periodic 
>> inspections.   The engineers design to some lenght of time for operation 
>> between inspections, but truth be told can't control all the factors 
>> which may make the system fail before the time expires.
>> Paul, kg7hf
>>
>>
>>> I hate to mention this, but as you mentioned it, many airframes are life
> cycle limited. So many takeoffs and landings and it's rebuild time.
> Aircraft engines are basically life limited to either so many hours, so
> many start cycles, or a combination.
>
> Fire extinguishers are life limited in years whether they are used or not.
>
> 73
>
> Roger (K8RI) 

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