Revision as of 04:11, 31 October 2023

Garmin GHA-15 Radar Altimeter

Intro

The Garmin GHA-15 radar altimeter starts reporting altitude somewhere between 300 and 550 ft.
Note: the 500 ft announcement is GPS altitude based, 300 ft and lower is then radar altimeter based.
It transmits at 24 GHz with very low power (milliwatts) compared to COM radios and transponders (20 / 150 Watts). 24 GHz is not the controversial frequency that has interference issues with cell towers.
It needs very little power and the connector accepts 22 AWG wire or thinner (you can transition to a 22 AWG lead wire near the connector if you want to run a thicker wire).

Videos

Threads

VAF
FB

Installation Manual

The G3X Touch installation manual covers the GHA-15.

Notepad

Connector
Note: unlike with D-Sub connectors, each pin needs at least 5/8 inch of plain wire (22 AWG or thinner) before thickening up for example for a splice or shielding. The distance between the end of the pin and where the wire exists the rubber gasket is quite long.
Note: on the rubbery back side of the connector, the printed "1" seems to be closer to the hole to the left of the "1", but pin 1 is to the right of the "1".
The center pin 22 is a bit off-center to the bottom. Together with hole straight below it, they constitute the vertical center axis of the connector. At the two circles above, the center axis splits between 21/15 and 14/1. At the outermost circle below, it runs between 7/8. The 4 holes above 22 are almost in a perfect square pattern.

On the (hard) back-end of the connector, the numbers are printed in a way that the "1" is actually closer to pin "1".

(as seen from the back of the connector where you insert the pins through the silicone seals)

Screw Torque

10-32 Stainless steel: 33 in lb

Tools / Parts Needed

K40 Positioner for DMC Crimper
The 10-32 mounting screws are included. If you need more, those are MS51958-67, e.g. McMaster part number 91400A833 (pack of 25, same bolts needed for GPS antennas)
4 x 10-32 nut plates, e.g. K1000-3 / MS21047L3
63/1000 2024T3 doubler, e.g. 4 x 4 inches

Builder made doubler example (Garmin doesn't provide template).
Optional: USB-B bulkhead debug connector (instead of Garmin pigtail part no 011-01782-00 which is just a coupling, not a bulkhead connector) at Amazon
Color code: Black: GND (GHA-15 pin 20), Red: +5V (GHA-15 pin 19), White: D- (GHA-15 pin 10), Green: D+ (GHA-15 pin 9)
The wire will fit through a 1/4 inch snap bushing (before crimping the pins)
Optional: Suitable 10ft USB-C to USB-B laptop cable at Amazon
Optional: Alodine pen to treat unpainted skin that will end up under the antenna: at Spruce.

FCC Report

FCC Record

@@ Line 17: / Line 17: @@
 ----
 ==== Notepad ====
-[[File:Screen Shot 2023-10-21 at 4.03.53 PM.png|400x400px]]<br>Connector<br>Note: on the rubbery back side of the connector, the printed "1" seems to be closer to the hole to the left of the "1", but pin 1 is to the right of the "1".<br>The center pin 22 is a bit off-center to the bottom. Together with hole straight below it, they constitute the vertical center axis of the connector. At the two circles above, the center axis splits between 21/15 and 14/1. At the outermost circle below, it runs between 7/8. The 4 holes above 22 are almost in a perfect square pattern.<br>[[File:Screen Shot 2023-10-22 at 10.47.20 PM.png|300x300px]]<br>On the (hard) back-end of the connector, the numbers are printed in a way that the "1" is actually closer to pin "1".<br>[[File:Screen Shot 2023-10-21 at 3.36.20 PM.png|331x331px]]<br>(as seen from the back of the connector where you insert the pins through the silicone seals)
+[[File:Screen Shot 2023-10-21 at 4.03.53 PM.png|400x400px]]<br>Connector<br>Note: unlike with D-Sub connectors, each pin needs at least 5/8 inch of plain wire (22 AWG or thinner) before thickening up for example for a splice or shielding. The distance between the end of the pin and where the wire exists the rubber gasket is quite long.<br>Note: on the rubbery back side of the connector, the printed "1" seems to be closer to the hole to the left of the "1", but pin 1 is to the right of the "1".<br>The center pin 22 is a bit off-center to the bottom. Together with hole straight below it, they constitute the vertical center axis of the connector. At the two circles above, the center axis splits between 21/15 and 14/1. At the outermost circle below, it runs between 7/8. The 4 holes above 22 are almost in a perfect square pattern.<br>[[File:Screen Shot 2023-10-22 at 10.47.20 PM.png|300x300px]]<br>On the (hard) back-end of the connector, the numbers are printed in a way that the "1" is actually closer to pin "1".<br>[[File:Screen Shot 2023-10-21 at 3.36.20 PM.png|331x331px]]<br>(as seen from the back of the connector where you insert the pins through the silicone seals)
 ==== Screw Torque ====

GHA-15: Difference between revisions