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From: john larkin <jlarkin_highland_tech>
Newsgroups: sci.electronics.design
Subject: Re: Ambient temperature control
Date: Mon, 01 Jul 2024 07:46:52 -0700
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On Mon, 01 Jul 2024 10:34:46 -0400, legg <legg@nospam.magma.ca> wrote:

>On Sun, 30 Jun 2024 18:14:32 -0700, Don Y
><blockedofcourse@foo.invalid> wrote:
>
>>Assuming you can keep a device in its "normal operating (temperature)
>>range", how advantageous is it (think MTBF) to drive that ambient
>>down?  And, is there a sweet spot (as there is a cost to lowering the
>>temperature)?
>>
>If all you're thinking of is MTBF, adding the complexity of an active 
>cooling element is a big step in the wrong direction for the system.
>
>Reducing the thermal impedance of the source, to ambient is the 
>usual way to go, when addressing a specific aging factor.
>
>https://ve3ute.ca/2000a.html
>
>If you're thinking of performance, It's cheaper and more reliable 
>to concentrate on reducing the temperature of the point source, not 
>the rest of the planet.
>
>RL

Tubes? The cathodes fail eventually. Reduce filament voltage and
suffer the reduced gain. Better yet, don't use tubes.

But for most parts that dissipate power, the big win is to have some
air flow. A fan can reduce the theta of your parts by 2:1.

Nowadays, parts are very good, with failure rates in the ballpark of
one failure per billion hours, the Bellcore and MIL217 FITS numbers.