MGL Avionics Stratomaster Ultra Horizon XL Owner’s manual
Page 46
Coolant temperature indicator
This instrument is used to display coolant temperature for water cooled
engines
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.
You can also select one of the alternative temperature senders in the Sender setup menu.
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.
Please note that you can also use the programmable probe in cases where you need to use
an existing temperature sender.
Oil temperature and Oil pressure indicator
Two related instruments are oil pressure and oil temperature. These instruments
are often used together but they are two independent instruments and you can
enable and place them individually.
Pressure is shown either in BAR or PSI as selected in the “mode and units setup menu”.
Temperature units are selected in the same menu and can be either degrees F or degrees
C.
The oil pressure indicator
Please setup the required oil pressure sender parameters in the “Sender setup menu”.
You should setup the following items:
a)
The maximum resistance of the sender (200 ohms in case of most VDO senders)
b)
The pressure required for maximum/minimum resistance (often 5 or 10 bars)
c)
The direction of the resistance versus the pressure. Most senders increase resistance
with pressure but there are a few that work the other way around.
You can enable either a minimum pressure level or maximum pressure level or both for
alarm monitoring.
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.
