From: N2EY
Date: Sun, 2 May 2010 12:31:56 EDT
Subject: What makes a real ham

On Apr 29, 6:01 pm, K0HB wrote:

MIL-STD 810 related to shock, vibration, salt spray, etc.
It is unrelated to any "performance" criteria.

IOW, it's an environmental specification, not a radio-performance
one.

I followed the links provided by K3FU and noticed that in each
description the rigs were only said to meet the shock and vibration
requirements of MIL-STD 810, not the entire specification. The
description also didn't mention which version(s) were used. IMHO those
are important points.

TEMPERATURE, both ambient and internal is an important factor. We
can't do the "wait a half hour" or "20 minutes" for the radio to warm
up. Radios don't get to sit in "room temperature" environments during
emergencies. [recall the 1928 "Amateur's Code" and the imperatives of
being ready for "emergency communications"]

Full water immersion for a specified period is a NEEDED specification
for an HT to perform in an emergency such as flood or torrential rain.
Operating mobile or pedestrian (with a manpack radio) has its own
needs for shock and vibration. Mobile installations aren't always
nice and plush with comfy seats for radios. Saying a pedestrian
station remains cushioned by the wearer ignores the fact that the
manpack wearer can fall down in rugged terrain.

Meeting the shock and vibration requirements is a matter of mechanical
design.

At first. That's when the designer first begins to "lay lead." What
comes next is the prototype which is (or should be) tried out in the
field or afloat...and (probably) several iterations of trying a fix
and
seeing how that performs. Sometimes that is easy, sometimes it is
difficult.

Meeting requirements such as salt spray, temperature and
humidity extremes, high altitude, water immersion, etc., is a
completely different game because each and every component must either
meet the specification or be protected from the environment.

A generalized statement like that indicates no experience with adverse
environments. One can "perform" like a champ at room temperature in a
residence environment but try it below freezing or in a vehicle that
has been in +118 degrees F all day (interior is MUCH hotter). I've
been
in both environments more than once and don't care to do it again, but
if there IS a need to have a radio perform, then I've had some
experience
in making them do just that.

Components that meet the spec are more expensive and fewer, while
protecting from the environment is complex and often impractical for
size/weight/cost reasons

If so there wouldn't be an aircraft able to fly today, nor with the
radios that enable comm and nav functions to tell pilots where they
are. That's been done for over 65 years now. Read some ARINC specs
and, especially, meetings minutes about their standards to get a
fuller picture.
Or, you do another thing I've done: work in an environmental test lab
and DO the testing...plus sweeping up the pieces of those designs
that failed testing. shrug

73, Len K6LHA