MGL Avionics Stratomaster Ultra “L” Owner’s manual
Page 37
Water temperature indicator
This is used for water or oil cooled engines. You select which by means of
selecting the appropriate label below the bargraph.
Please note that the senders for water and oil temperature are usually different
and using the wrong sender will result in incorrect readouts.
Temperatures can be displayed in degrees C or degrees F. Use the mode menu
to select your preferred choice.
Water temperature measurements requires the sender available from MGL
Avionics. This is a standard automotive sender with the following characteristics:
900 Ohms at 20 degrees C and 93 ohms at 85 degrees C.
You can also use the precision semiconductor temperature sender available from
MGL Avionics. We recommend the use of this sender for applications were you
need to know the exact water temperature.
When procuring oil or water temperature senders, be aware that these senders are based
on NTC resistors and typically have a fairly large tolerance. They tend to be more accurate
at higher temperatures but can have large errors at low temperatures.
We suggest that you use a multimeter in combination with the ambient temperature probe of
the Stratomaster Ultra to verify that you have the correct sender.
Using the Stratomaster connected to a 12V battery or similar power supply, use the included
ambient temperature probe to measure the temperature of a jug filled with boiling water.
Insert the temperature probe in question connected to the resistance measurement setting
of your multimeter. Ensure that the top terminal of the sender remains dry to avoid
measurement errors.
Wait until the temperature drops to 85 degrees and then take a reading of the resistance. A
tolerance of up to 5% is acceptable.
Oil pressure indicator (without oil temperature)
Should you have a requirement to measure oil pressure, select the oil pressure
bargraph display by selecting the label to “OILP” in the engine detail setup menu.
Please select the required oil pressure sender setting under the “Sender setup
menu”.
The RDAC IV EIS supports standard resistive automotive oil pressure senders.
These are available in a number of different resistance ranges and as a
consequence, the Stratomaster Ultra allows you to select resistance range in steps
of 50 ohms from 50 ohms to 1000 ohms. The sender fitted to a Rotax 912 for
example has a 200 ohm resistance. The RDAC expects resistance to increase with
pressure, with the maximum resistance at 10 bars (145 PSI). Should you have a
sender with a maximum pressure rating of less than 10 bars, please select the
resistance setting in such a way that correct pressure reading would be obtained at
the maximum pressure sender output.
Oil pressure can be displayed in PSI or BAR. Select your preference in the “mode menu”
(see page 42).
Please note: Should you switch on alarms for the oil pressure reading, the alarm will be
activated if oil pressure falls below the set level. This implies that the alarm will be activated
should you switch your engine off.
Set the required alarm level in the Engine detail setup menu (page 42). Most requirements
would use a minimum pressure of 1.5 to 2.0 Bars (20 – 30 PSI).
