TM Page 11
3.2
TRANSMITTER TX34/1/IFM
The single channel (plus power supply monitor and internal temperature channels) TX34D/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 a programmable instrumentation amplifier, stabilised bridge excitation supply
of 4.096VDC, 16 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 the RE3D sending control pulses via the inductive power supply. A remote shunt
calibration facility is incorporated into the input stage and is activated by a command from the RE3D. A shunt calibration
resistor is connected across one arm of the strain gauge input circuit for a period of 10 seconds, this is either a DC or AC
signal at various frequencies. 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 shunt calibration
resistor. The transmitter housing is drilled with 4 x M3 clearance holes for attachment of the screening cover and mounting
baseplate.
P1
P2
P3
P4
P5 P6
P8
P9
P7
P10
P11
Figure 3 - TX34D/1/IFM Transmitter Connections
P1= +4.096V EX
P2= + SIG
P3= - SIG
P4= 0V EX
P5= R cal
P6= R cal
P7= PCM TEST
P8= +V IN
P9= 0V & HOUSING
P10= LOOP ANT
P11= 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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