[time-nuts] 5370A vs 5370B
David Forbes
dforbes at dakotacom.net
Wed Mar 10 16:26:20 UTC 2010
At 4:10 PM +0000 3/10/10, Mark Sims wrote:
>Yes, I replace the standard HP fan with a MUCH quieter one. I get
>mine from a local surplus shop. It is made by AAVID. it draws 120
>mA at 12V and I run it off the 10V supply (which is somewhat over
>10V).
>
>Before getting all whiny about overheating, careful HP engineers
>putting that obnoxious hurricane in for a reason, etc... know that
>I put several thermocouples all over the guts of the machine and
>found no significant changes in cooling. I have had modified
>machines running continuously for many years.
It's reasonable to assume that HP engineers put in twice as much fan
as needed by 95% of their customers, to prevent problems with that
last 5% that run the thing in an extreme environment. If the
counter's spec sheet says it will run at 50C, then it's gotta be able
to run for a couple years at 50C without failure. So your 25C office
can use a much quieter fan.
Our telescope at 3500m altitude, on the other hand, needs all the fan
noise it can get since the thin air is only 50% as effective at
cooling as sea-level air is.
--
--David Forbes, Tucson, AZ
http://www.cathodecorner.com/
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