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3
TRANSMITTERS
3.1
TRANSMITTER TX31D/1/IFM
The single channel (plus power supply monitor channel) TX31D/1/IFM transmitter is a compact, low profile design, used
when a minimum diameter for the shaft mounted hardware is required. The lightweight machined aluminium housing is
drilled to accept a screening cover and slotted base-plate fixture (for use with the shaft clamp assembly kit CAK). Power
supply is normally by inductive coupling into a single turn pickup loop, either wound around the shaft periphery (and
separated from the shaft by an insulating standoff layer), or located within a groove machined into the split-ring assembly
O.D. The transmitter may also be powered by batteries. For example, two ½ AA size lithium cells usually housed within a
TX.MTGS split ring assembly, or the TX31 battery unit.
Circuitry consists of an input filter followed by an instrumentation amplifier, stabilised bridge excitation supply of 4.096VDC,
12 bit A/D converter plus control logic, rectification circuitry to convert the incoming AC inductive power to filtered DC (not
used if battery powered) and finally, a 10.7 MHz fm output stage. The input amplifier gain controls the overall system
sensitivity and is set by an external resistor "Rg", which is user fitted between two pins on the transmitter. A remote
calibration facility is incorporated into the input stage and is activated by temporarily interrupting the transmitter power
supply (i.e. turn off demodulator module power). When power is re-applied, a shunt calibration resistor is connected across
one arm of the strain gauge input circuit for a period of 10 seconds. The shunt calibration resistor is user fitted across two
solder pins.
Signal transmission is by inductive coupling of the 10.7MHz f.m. carrier from a single-turn loop wound around the shaft (in
an inductively powered system this loop also collects power) and an inductive head IH1 (IH2 or inductive loop IL2 for
inductively powered transmitters). Transmission range is typically 50-200mm, reducing to 10-15mm for inductively powered
transmitters, this being the maximum airgap across which sufficient electrical power for the transmitter can be transferred.
In construction, the transmitter circuitry is encapsulated in epoxy resin within a machined aluminium housing with solder
pins providing the input connections to the strain gauge leadwires, inductive power/pickup loop and sensitivity setting/shunt
calibration resistors. The transmitter housing is drilled with 4 x M3 clearance holes for attachment of the screening cover
and mounting baseplate.
P4
P3
P2
P1
P6
P5
P8
P7
P10
P9
P11
P13
P12
Figure 1 - TX310D/1/IFM Transmitter Connections
P1= 0V EX
P2= - SIG
P3= + SIG
P4= +4.096V EX
P5= R cal
P6= R cal
P7= R gain
P8= R gain
P9= +V IN
P10= 0V & HOUSING
P11= PCM TEST
P12= LOOP ANT
P13= LOOP ANT
IF THE TRANSMITTER IS CLOSE TO INDUCTIVE HEAD:
1) Use screened cable for gauge leads
2) Fit supplied metal cover to screen transmitter circuitry
3) Connect signal cable screen to transmitter housing
Failure to do this may result in a zero shift once per
revolution due to inductive power magnetic field pickup
Содержание TX31D/1/IFM
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