NorthstarM3.com
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Discontinuance of Data Service Notice
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| Dedicated to the outstanding Northstar M3 GPS Approach receiver. |
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The M3 is considered one of the easiest to use of all IFR GPS units. During an approach, the M3
will automatically sequence through each leg. This allows the approach to be
flown "hands off". Other GPS boxes require the pilot to manually sequence legs
upon completion of turns. If you spend time browsing
message boards on-line it's common to read comments similar to:
"After flying 20 hours with my new XYZ123 GPS it's starting to become easier."
A typical M3 comment is more likely to be like this: "After spending 15 minutes reading the M3 quick start guide I was flying GPS approaches." On the used avionics market the Northstar M3 represents an outstanding value. The savings can be significant when compared to some of the newer GPS/Comm units. The M3 does not have a moving map, only a single line display. The Northstar engineers deserve credit for leveraging the single line to its maximum capability. Once considered an expensive luxury, moving maps can now be had for about the cost of a fill-up of 100LL. Even a simple VFR moving map can significantly enhance situational awareness.
Here are some ideas for budget friendly moving maps:
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Installing an M3 for approach use requires integration with an altitude encoder. The M3 can accept either serial data or traditional gray codes. If using gray codes you may need to place isolation diodes in the harness going to the transponder. Modern transponders like the Garmin GTX 327 and 320A already have built-in diodes. Older transponders such as the Narco AT-150 and ARC RT-359A will require isolation diodes. Some installers have reported success using 1N4148 diodes.
For serial data, the Northstar 2006 or current production Icarus 3000U can be used to translate gray codes to serial output.
The M3 requires forced air for cooling. Cooling fans are preferred over air scoops as they provide a clean and dry air source. Here's a good article on avionics cooling.
The M3 came with a floppy disk containing files to assist installers.
Click here to download as a zip file.
Note: This zip contains a copy of Advisory Circular AC20-138 which has been replace
by AC20-138A. One significant difference is the suggestion in AC20-138A that GPS
installations be considered a minor modification.
Click here to read AC20-138A.
(read Tom
Roger's comment on AC 20-138A). Even if you local FSDO agrees that the installation
is a minor modification, they may ask for a 337 to use as a basis for your FMS which
an FAA inspector must stamp 'FAA Approved'.
Mid-Continent Indicator
The Mid-Continent MD40-64L (L for lighted) is a CDI/Annunciator designed
specifically to work with the Northstar M3. If the install makes use
of an existing CDI then the Mid-Continent MD41-800 annunciation control
unit can be used.
Mid-Continent manuals can be found
here.
Antennas
The M3 installation manual lists three approved antenntas, the AN120, AN135, and AN155.
The AN120 is a Comant 405-7 which has been replaced by the newer Comant 405-200.
The AN120 is a teardrop shaped antenna that shares the same foot print as the M1 Loran
antenna making upgrades easier if replacing an M1 with a top mounted antenna.
Some have reported success using a King KA-92 which has similar specs as the AN120.
The AN135
is probably the most common antenna used with the M3. The AN135 is smaller than the
AN120 and uses a different hole pattern than that used for AN120 and Loran antenna.
VHF Radio Interference Test
As per AC 20-138A, IFR GPS installations should be tested to ensure VHF transceivers do not
interfere with with GPS reception. This involves transmitting on specified frequencies and noting
the affect on the signal-to-noise ratios displayed on the M3.
From AC 20-138A Paragraph 22:
(ii) Evaluate the following VHF frequencies (25 kHz channels): 121.150 MHz 131.250 MHz 121.175 MHz 131.275 MHz 121.200 MHz 131.300 MHz (iii) For VHF radios with 8.33 kHz channel spacing, evaluate the following VHF frequencies: 121.185 MHz 130.285 MHz 121.190 MHz 131.290 MHz
Comm Integration - SmartComm C1 option
The M3 can be wired to control frequencies on the headless version of the
Becker 4201 transceiver.
Finding a shop to install your Northstar may take some time as many shops
do not have recent Northstar experience.
If you install Northstar avionics and would like
to be listed on this site let us know.
Read the original M3 press release.
