One have to consider the specs from the manuals about operational
conditions. Most manuals for HP Test Equipment states under "General
Specificatioms - Environmentals" operating temperature 0 - 40, even 0 -
55 dgC for HP8866A/B.
That means that the intake air can be up to 55 dgC, and the beast will
still run cool enough. Imagine how hot the output will be!
Try to measure your input and output temperature under normal conditions
in your shack, and then calculate your margin. You may have a margin of
25 - 30 dg. Then select fans that will deliver adequate air, and enjoy
how
quit it can be.
Best 73 de OZ5TG, Vern
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----- Original Message -----
From: "Dave C" <davec2468@...>
To: "Test equipment list" <test-equipment@...>;
<hp_agilent_equipment@...>
Sent: Thursday, January 03, 2013 6:03 PM
Subject: [hp_agilent_equipment] Choosing a quiet replacement fan
I read occasionally that owners of T&M equipment tire of the noise a
cooling fan makes and asks for help to determine if/how a quieter
replacement can be found. There are many factors at play in such a
decision, none as simple as "it's quieter".
This web site addresses choosing a fan for PC enclosures, and many of
the
criteria are the same (heat being the most important one for us):
<>
A quote:
"Over the years, we have observed one clear phenomenon about fans and
cooling: The relationship between airflow and temperature invariably
becomes exponential at some point. Increase airflow from nothing to
something, and the drop in temperature can be dramatic. Keep
increasing
airflow, and the cooling improvement becomes less and less
significant,
until at some point, the temperature hardly drops at all. The trick,
for
the PC builder who seeks both good cooling and low noise, is to find
the
point where any decrease in airflow (or fan speed) effects a
significant
increase in temperature, while only a very large airflow increase
effects
a significant temperature drop. In other words, once you have enough
airflow, additional airflow has very little cooling effect, so all
you're
doing is increasing noise. "Enough airflow" is not a constant, of
course,
it varies for each system of components."
FYI,
Dave
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