
INSTALLATION & OPERATION
MANUAL
SP718-MA-24-C
24 Volt Modulated Carrier Ampli fier
4-20mA Transmitter
DOC#: MN-718MA-24.doc
SPECIFICATIONS

SP718-mA Modulated Carrier Amplifier
Temperature:
Frequency 0 – 3500 Hz w/ 50kHz carrier (requires P/U Coil 1 – 1.3
4mA @ 0Hz, 20 mA @ desired Full Scale Frequency
FM Approved, CSA Certified
Operating 0 – 70oC
Storage –20 – 85oC
Reverse Polarity Protected
Consult factory for other I nput Voltages
mh)
Full Scale Range 25Hz – 3500 Hz Selectable
Consult factory for other Rang es
Response Time 95% of change in 1 second
Linearity .3% F/S
Tempco <2% of Reading over entire Temperature Range
Maximum Load Resistance 500 ohms
Features:
LED Power Indicator
Mounts directly on flowmeter
Class I Groups B, C, D
Class II Groups E, F, G
The SP718-mA Modulated Carrier Amplifier and Analog Transm it t er is a meter mounted device designed to
combine the advantages of the Modulated Carrier principle with the convenience of an analog output in a
single PCB assembly. The SP718-mA linearly converts the detected carrier frequency shift rate t o an
equivalent 4-20mA current output. When incorporated with a turbine flowmeter a current representat ion
proportional to flow is obtainable. Data transmission in a curr ent format exhibits excellent noise immunity
and the capability of long distance transmissions.
The SP718-mA produces a carrier frequency in conjunction with an RF pickup coil, detects the shif t in t he
carrier frequency (Modulation) that occur s with the passage of magnetic mater ial and linearly generat es a
4-20mA output that is proportional to the rate of modulation.
A full-scale freq uency range of 25-3500Hz is jumper selectable. The Span Adj ustment establishes the
frequency point at which a 20mA output is achieved.
The Modulated Carrier principle introduces no drag on the passing magnetic device; therefore, when
utilized with a turbine flowmeter extension of the flowmeter’s nominal linear rang e at the low end of the flow
spectrum is realized. This parameter is particularly useful when measuring a low mass gas and the
operating flowrate is at the f lowmeter ’s low end.

SP718-mA Modulated Carrier Amplifier
All test equipment power cords should be equipped with 2-prong ‘cheat er ’ plug s.
Connect Flowmeter with RF Pick-up Coil to J1-1,2
Connect Power Supply Positive & Negative Leads to J1-6,5 Respectively
Connect O’Scope Positive & Negative Leads to J1-1,2 Respectively
Install Jumper @ JU1-3 for desired Full Scale Freq uency Range
Turn Power Supply ‘ON’, LED D1 Illuminates & O’Scope displays a 50KHz +/- 5KHz
6Vp-p Carrier Sinewave
Adjust ‘ZERO’ (R25) for a DMM Indication of 4.00mA
Set Frequency Generator function to Sinewave, Amplitude to 500mVp-p with 2.5VDC
Generator POSITIVE Lead to TP1 (R11) & NEGATIVE Lead to J1-2.
Adjust ‘SPAN’ (R23) for DMM Indication of 20.00mA
Reduce Signal Amplitude of Frequency Generator to Zero, Adjust ‘ZERO’ (R25) for
DMM Indication of 4.00mA if necessary
Increase Signal Amplitude of Frequency Gener ator to 500mVp-p, 2.5VDC OFFSET;
Adjust ‘SPAN’ (R23) for DMM Indication of 20.00mA if necessary
Adjust Frequency of Freq uency Gener ator to 0, 25, 50, 75, & 100% of Full Scale
Frequency of Step H
To check for Linearity at any Freq uency Point, incor por at e t he following formula -
Example: Assume Maximum Frequency Point = 2KHz (20mA Point)
Check for Linearity at 750Hz
6 + 4 = 10 DMM Should indicate 10.00mA at 750Hz
BENCH TEST CALIBRATION PROCEDURE
Required Equipment: Power Supply 12-24VDC
Digital Multimeter ( DMM)
Frequency Generator
Frequency Counter
Oscilloscope
Refer to Figure
Test Procedure:
R LOAD
R SENSE
Connect DMM Positive & Negative Leads to J1-3,4 Respectively, Set Function to mA
D)
F)
OFFSET & Frequency to desired Full Scale Frequency. Connect Freq uency
J)

SP718-mA Modulated Carrier Amplifier
SIGNAL IN +
SIGNAL IN –
ANALOG OUT +
ANALOG OUT –
DCDC+
NOTE: DIMIENSIO NS ARE IN INCHES
F/S Frequency Select
JU1 25-140 Hz
JU2 125-700 Hz
JU3 675-3500 Hz
©2009
Pub. No. MN-718MA-24
(09/09)