PS Magazine - TB 43-PS-664

PS, The Preventative Maintenance Monthly

ISSUE 664

MARCH 2008
PS Magazine - TB 43-PS-664 - Page 22 of 33
41
PS 664
MAR 08
T
he light interference F
lter (LI±), NSN 5855-01-379-1410, is a light protection
F
lter for the image tube on your AN/PVS-7B, -7D or -14 night vision devices.
Your image tube cannot recover from bright light damage. The pixels in the tube
will be damaged and leave a black, empty streak, an arc or spot.
While your NVG is pretty smart by cutting off when exposed to bright light, it’s
not fast enough when exposed to extreme bright light such as the light emitted by
tracers, lasers, and fl
ares.
±olks in the know say a lot of tubes are being replaced because of direct light
damage.
In the AN/PVS-7B and -7D
technical manuals, TM 11-5855-262-
10-2 and TM 11-5855-262-23&P-2,
and in the AN/PVS-14 technical
manuals, TM 11-5855-306-10
and TM 11-5855-306-23&P, the
instructions say, “The LI± is to be
used at all times.” This instruction
is repeated over and over and over
again in these manuals.
D
rop NSN 1240-00-137-7768, shipping and
storage container for the AN/PVS-5 night
vision device, from your component-of-
end-items list. Check any of those “special
NSNs lists” you have and make sure
that NSN is deleted on them, too. That
container is no longer available.
Instead, use shipping box, NSN 8115-
00-550-3574, as your shipping and storage
container for the night vision device. This
box is one of the “Fast Pack” boxes that
are supplied by GSA.
Yet, LI±s are still being removed and not used.
Why?
One reason may be that some of you don’t think you get as good an image with
the LI± in place. And you’re right. There is a slight reduction in system gain, but the
emphasis is on the word
slight
. If you’re getting too great a reduction, try cleaning
the LI± using water and lens paper, NSN 6640-01-459-4239. If it’s still a problem,
get a new LI±!
If the LI± is dirty or scratched or otherwise damaged, it could be you’re not using
the sacriF
cial window, NSN 5855-01-246-8271. Use it! Its job is to give its life so the
LI± and the tube can survive.
Additionally, some of you
are removing the LI± to attach
things like the 3X magniF
er and
the compass. The magniF
er, the
compass, the sacriF
cial window
and the lens cap will all F
t into
the end of the objective lens
with the LI± in place.
±inally, it is essential that you
use the objective lens cap, NSN
whenever
the NVG is not in use to protect
the image tube from exposure
to sunlight.
AN/PVS-7B, -7D, -14…
AN/PVS-5 Night Vision Device…
Shipping and Storage Container
You
Need
the
LIF!
Even though this container is no longer
available, store NVD safely for shipping.
SacriF
cial
window
LI± with container wrench
Objective
lens cap
LI±
Ridges
Container/
wrench
664.40-41.indd
1-2
1/27/08
7:04:11 PM
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