Trivec-Avant AV 2095 UHF Satcom Antenna System

Brooke Clarke 2013

    Gyroscopic Azimuth Sensor
    Antenna Positioner
        Front Panel Connectors
        DC Power Cable
        Stepper Motor & Controller
    Interconnect Diagram


The military has a number of UHF satellites in Geosynchronous orbit (Wiki).  When you want to have a 2-way conversation by means of these some amount of gain in the antenna means it needs to be pointed at the satellite.  For a portable (man moveable but used in a fixed position) like the LST-5 radio, this is easily done using a simple tripod to support the antenna.

But when you want to use one of the Geosynchronous UHF satellites from a moving vehicle then pointing the antenna at the satellite becomes problematical because it needs to be steered in azimuth.  There is no need for elevation steering because a land vehicle can not move far enough to require an elevation change using one tank of fuel.  This antenna system is designed to allow a vehicle to keep it's UHF satcom antenna aimed at a given satellite while driving on reasonable level ground.



The antenna mast will have a central Type-N Jack and also a Micro-D connector with 9 sockets.
Photo of just the antenna at:  Photos below courtesy of Brandon.

Trivec-Avant AV 2095 UHF Satcom Antenna System
Trivec-Avant AV 2095 UHF Satcom Antenna System Trivec-Avant AV 2095 UHF Satcom Antenna System

Gyroscopic Azimuth Sensor

This BEI QRS11 Gyrochip gyroscopic sensor in mounted inside the antenna positioner box (Fig 5)
The spec for long term drift is 0.2 Deg/sec so in 24 hours it might drift 17 degrees.
The under 100 second drift rate is 0.002 deg/sec so taking 5 seconds to make a right angle turn the drift would be 0.01 degrees.

Antenna Positioner


Steering Assembly
p/n: 2095-137
for UHF Satcom Antenna System
p/n: AV 2095-2
s/n; xx   System wt.: 28 lbs.
Trivec-Avanet Corp. FSCM 60188
Hunington Beach, CA 92647, USA

Front Panel Connectors

mil xxxx-10 10 male pins 3-lug, 3/4" O.D., 5 internal key slots
marked Bendix 21-204412-10P  9405 on inside
Has red & black wires and Black & white wires (4 total wires)


Vehicle +24 supply
Vehicle ground
? Left/Right Up/Down ?
?              ?                 ?
C, D
G, H
J, K
not used

DC Power Cable

Made from:
Power-Pole connectors in "24 Volt" configuration
Cooner Flex Wire with Silicon insulation
Trivec-Avant AV 2095 UHF Satcom Antenna
                      System DC Power Cable

Type-Nf jack.

Fig 1 Outside 3/4 view
Cap installed on mast socket
Disk beside mast socket is locating pin
to keep mast from rotating.
Trivec-Avant AV 2095 UHF Satcom Antenna System
                    Antenna Positioner
Fig 2 Inside Left Plate
Trivec-Avant AV 2095 UHF Satcom Antenna System
Fig 3 top with cap removed
showing the coax rotary joint and
micro D 9 pin connector
Trivec-Avant AV 2095 UHF Satcom Antenna System
Fig 4 Step motor, control board, gyro,
American Precision Ind cmd-50 stepper motor ctrl
The black box mounted behind the front panel is a
Caledex DC/DC Converter 28D5.1000
18 - 54 VDC In
+/-5 VDC Out @ +1100/-900 ma
Trivec-Avant AV 2095 UHF Satcom Antenna System
Fig 5 BEI QRS11 Gyrochip gyroscope
Trivec-Avant AV 2095 UHF Satcom Antenna System
                  MEMS Gyroscope

Stepper Motor & Controller

There are signs of corrosion at the bottom of the stepper motor (water got in the box?. . . or ?
Patent numbers on the motor:

3206623 ELECTRIC SYNCHRONOUS INDUCTOR MOTOR, Superior Electric Co., Sep 14, 1965, 310/162; 310/49.35; 310/156.64; 310/263
3734254 STEPPING MOTOR WITH AUTOMATIC BRAKE, Sigma Inst. Inc., May 22, 1973,  192/16; 192/223.1; 318/372
3777196 LOW-INERTIA SYNCHRONOUS INDUCTOR MOTOR, Sigma Inst. Inc., Dec 4 1973,  310/156.64; 310/49.32; 310/162
3956650 Laminar-rotor synchronous inductor motor, Sigma Inst. Inc., May 11, 1976, 310/156.65; 310/49.41; 310/162
4025810 Low noise synchronous motors, Sigma Inst. Inc., May 24, 1977,  310/162; 310/156.64
4255696 Synchronous motor system, Sigma Inst. Inc., Mar 10, 1981, 318/696; 310/49.43; 318/400.23 - fractional stepping

American Precision Ind cmd-50 stepper motor Controller box
with sticker: Sold by Servo Systems Co.
Connections are:

G/W: white
Gen: green
Red: red
R/W: Red/White
To Stepper Motor
Run/Reset: nc
Half/Full: nc
Step In: white
CW/CCW: Green
ENA/nopwr: gray
5 VDC In: orange
ROI & ROI: resistor
Common Ground: black

+ Voltage Supply: Violet
To Controller PCB



Interconnect Diagram


RT-1319 VHF-Hi & UHF Aircraft tranceiver
VRC-83 part of the GRC-206 FAC system

Mike Murphy  AV-2095
William Perry - DC Power Cable connector
Cooner Wire - wire for power cable
UHF-Satcom - a lot of info about UHF SATCOM
FM 6.02.90 Aug 2004 UHF TACSAT/DAMA - App E operating procedures for the LST-5D

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Page created 28 March 2013