TVS-2B Night Vision Scope MX-7794B
Crew Served Weapon Night Sight
© Brooke Clarke 2005 - 2008
Description
Operation
What Goes Wrong
Power
BA-110
Battery Eliminator
Manuals
Links
Description
This is a Vietnam era Crew Served
Weapon Night Vision Device. It uses a Schmidt-
Cassegrain
optical system. The manual says 7 power. The objective
diameter is probably 5.5 to 6 inches.
Image Intensifier
Marked: Image Intensifier, Type:
MX-7854/UV, FSN 5855-051-2702, U.S. Property, Ser. No. 17452, 8524
2.74" diameter x 7.3" long. 34mm flat exit diameter. 1.4"
dia. flat fiber optic plate.
Oscillator
Marked: Oscillator H.V.,
M?052374B(F10), Lectrospace Co., Westbury, N.Y., Contract No., DAARC7-69-C-032,
Ser. No., 3922
The oscillator has a socket on it's bottom that plugs directly into a
pin on the image intensifier.
Focus
Turning the Focus knob clockwise moves
the main mirror back
Lens Cap - Filter
The front cover
contains a small open segment and a filter wheel with 3
neutral density filters, each more dense than the prior one as well as
an open window. This would allow testing the scope in the
daytime. Using the darkest filter on a cloudy day is about the
same as no cover at night with 1/2 moon on distant hills.
Reticule
This sight is intended for use on
either the M2 .50 cal. Machine Gun (M2 rtucule) or the 106 mm
Recoilless Rifle (M40 reticule).
This on is setup with the M2 reticule and straight through
eyepiece. When the M40 reticule is used the right angle eyepiece
is used.
The reticule gets it's electricity from a cble that goes into the front
of the front lens element. This is not a high voltage wire.
Operation
The switch with the pointer has 3
positions. CCW is OFF, then scope ON, then Scope and Reticule ON.
The large knob controls objective focus and the eyepiece controls
focusing on the image intensifier tube output window.
When looking up at the stars at night there's a much larger number of
start visible than with the naked eye. Also there is no night
adaptation of the eye needed since the scope has a bright output.
But you probably can see fainter stars with night adapted eyes.
The output color is green to match the peak in a human eye's spectral
response.
This scope was not intended to be hand held, and doing so is very
difficult. Need to figure out a way to get it mounted on a tripod.
Upon receipt the unit appeared to be
DOA. The 1½" diameter knob on the top of the scope gives
access to the oscillator, which can simply be lifted out.
Plugging it in and removing it a few times cleaned it's contacts and
now it's working OK. It again failed to start and cycling the
oscillator up and down a couple of times fixed it. Maybe it needs
cleaning with a pencil eraser?
Power
BA-1100 Battery

The
original battery was the BA-1100/U
6135-00-926-0827 which is one of the long obsolete Mercury based
batteries. A
prior owner has made a simple battery adapter by taking a four "AA"
battery holder where all the cells are wired in series and attaching a
metal plate to each end. The "battery" goes into the scope
Positive (+) end first. The scope case is a negative ground.
The 4 AA battery holder has both the + and - terminals on the same
end. This adapter is made by placing a metal plate on the
terminal end with the positive contact connected to the positive
terminal and with epoxy or hot melt glue insulating the negative
contact. A diode is connected from the negative spring to the
opposite end and goes through a small drilled hole to the negative
metal plate that is glued to insulate it from the jumper eyelets on
that
end. Single sided PCB material would be a good material to use
for this.
The BA-1100 used 4 Mercury cells which when fresh put out 4 * 1.35 = 5.40 Volts. When dead it was 5.0 volts.
If 4 AA rechargeable batteries were to be tried they would be about 1.4
V * 4 = 5.6 Volts fresh and 1.2 * 4 or 4.8 when dead. So although
they probably would work when fresh, the useful life would be short.
If 4 AA Alkaline cells are used the fresh voltage would be 4 * 1.52 or
6.08 which is a little too hot, that's why the diode is in the adapter
to drop the fresh voltage down to about 5.6, very close to the Mercury
battery. The 5.0 volt dead voltage for the adapter occurs when
the cell voltage is 1.4 so when the AA cells no longer work in this
adapter they would still power a flashlight.
Battery Eliminator
This is a battery eliminator that replaces the BA-1100/U Mercury
battery that's long obsolete. It's line powered from regular 115
VAC single phase power.

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Power Converter for Night Vision Sights
AN/PVS-2, AN/PVS-2A or AN/TVS-4
Input: 115 VAC single phase 60 Hz
Output: 6.8 VDC
|
MS3110P-14-5-5P
shown with pin A next to wide keyway
at top. Letters go clockwise.
|
DC output is case threads
and spring.
|
The A.C. cable will use a MS3116E-14-5S or MS3116F-14-5S or
MS3116P-14-5S connector.
The MS3116E-14-5S is the lowest
cost and is available from
William Perry Co.
Wiring is A.C. line to pins B and C.
Earth ground to pin E = threads on battery eliminator and connector shell.
Open circuit output about 6.6 Volts.
Although only three Night Vision Sights are listed on the batery
eliminator it should work for anything that uses the BA-1100/U like the
TVS-2B.
These are available from
Mike Murphy on his
NIGHT VISION, SURVEILLANCE AND RELATED ITEMS web page.
Manuals
TM-11-5855-203-10
Night Vision Sight, Individual Crew Served Weapon AN/PVS-2 (NSN
5855-00-087-2947), AN/PVS-2A (5855-00-179-3708) and AN/PVS-2B
(5855-00-760-3869)
TM-11-5855-203-13 Organizational and DS Maintennance Manual, Night
Vision Sight: Crew Served Weapons Models 9927 and 9927A, April 1967
TM-11-5855-203-23P Technical Manual Organizational and Direct Support
Maintenance Repair Parts and Special Tools Lists (Including Depot
Maintenance Repair Parts and Special Tools) for Night Vision Sight,
Crew Served WeaponsAN/TVS-2 (NSN 5855-00-087-3144), AN/TVS-2A (NSN
5885-00-791-3358) and AN/TVS-2B (NSN 5855-00-484-8638), November
1977 Change 1
TB 11-5800-212-24 Procedure for Determining Serviceability of Night
Vision Sight
Individual Served Weapon Sight, Crew Served Weapon AN/PVS-2 and
AN/PVS-2A; Night Vision Sight, Crew Served Weapons AN/TVS-2B; Night
Vision SIghts, Mimiaturized AN/PVS-3 and AN/PVS-3A; and Night Vision
Sight, Tripod Mounted AN/TVS-4 and AN/TVS-4A.
TC 23-13 Crew-Served Weapon, Night Vision Sight, Jan 1967
Links
Fort Belvoir Army Night Vision Labs
- Early Attempts at
Night Vision Technology - 1967 - Pulse Gated I2-TVS-2 Crew Served
Weapon Night Sight
A
History of the United States Army Communications-Electronics Command
(CECOM) - "Second generation night vision devices (image
intensification technology)
replaced the first generation "sniper scope" (near infrared
technology) of World War II. The Small Starlight Scope AN/PVS-2, the
Crew Served
Weapons Sight AN/TVS-2, and the medium range Night Observation Device
AN/TVS-4
all saw service in Vietnam. The Night Vision Laboratory, which was
attached to
ECOM in 1965, began their development in 1961. Production of the
AN/PVS-2 began
in 1964."
S.T.A.N.O. Components
- Night Vision dealer
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