Building the Stratux ADS-B In receiver into an RV-10
Much improved radio performance with an external antenna

After upgrading my RV-10 to 2020-compliant ADS-B Out via a Garmin GTX330ES transponder and GNS480 position source, I was eager to get the benefits of ADS-B In including the enhanced traffic information available for aircraft with a 'qualified' ADS-B Out signal.

Being a homebuilder with fine memories of building Heathkit electronics, the Stratux receiver was a natural project to undertake to get ADS-B In, particularly since I already had a Foreflight subscription for the iPad.  I followed the online instructions for the Stratux and was able to quickly assemble a dual band receiver with 3-D printed case, and got it working in the RV-10 using the little telescoping antennas that come with the SDR (software defined radio) modules, mounting the unit with velcro on the crossbar behind the rear seats, with the antennas 'seeing through' the composite upper shell.  But I wasn't fond of using the cell phone battery pack, and found that if I used a standard issue 3 ft. micro-USB power cord the SDR units would not boot up due to insufficient current.  That problem was solved by getting heavier duty USB power cables from Amazon, but I still had cords snaked around the back seat and the battery pack just sitting on the center tunnel cover.  First upgrade was to build in a combined 12v. socket + USB outlet from O'Reilly auto parts (P/N 18003, $12.99), routing a 14 ga. 12v. wire and ground return from the main fuse block to the flap pushrod tube cover below the right side passenger's seat.  This solved the power problem but not the exposed wiring problem.  And I noticed that flying up and down the west coast over metropolitan areas like Sacramento, Portland and Seattle, the largest number of towers the unit would report receiving was two.

So the next iteration was to install a low cost ($17) external ball-on-stick 978mHz USB antenna on the aircraft belly way back in the tailcone (to get it away from both transponder and comm antennas on the belly), and route some RG400 coax forward to the receiver mounted in front of the right rear seat.  The key adaptations needed to make this work were:
  1. an adapter to go from the MCX coax connector on the SDR unit to a female BNC panel mount connection on the Stratux case
  2. a panel mount USB power supply mounted near the Stratux; and
  3. a USB panel mount and extension, for the wifi module to put it outside the 'Faraday cage' created by the metal flap pushrod cover.
After flying with the dual band receiver for a few months, I decided to forego the separate 1090 receiver, since although it had some entertainment value to see the flight number of airliners flying 20,000 feet above me, it was not really flight critical information.  This meant that only a single external antenna connection would be needed, and the power draw of the unit would be a bit lower (total being 2 amps at 12v as it turned out).

The external antenna setup has worked far better than I anticipated.  In areas where I could only receive 1-2 towers, Foreflight is now showing up to 7, and averaging 5-6, including remote mountainous areas such as the Oregon Cascades and California Siskiyous.

So although I spent some on gadgets that I am not currently using (e.g., the second SDR and the battery unit), starting from scratch it is clearly possible to get a permanent installation of the Stratux into a -10 for under $270 (plus shipping of the various pieces).  See complete parts list and prices below.

Here are some photos of the components and final installation:

Stratux Case


This is the Stratux in its 3-D printed case (originally designed for the folding telescoping antennas that come with the SDR radio units).  I removed the 1090 SDR, and the supplied antenna for the 978 SDR, and plugged in the RF coaxial coax cable assembly BNC female to MCX male right angle 6'' antenna cord.  Cut a hole in the case bottom to mount the female BNC connector.

A six inch USB flexible M-F extension routes though a channel filed on the left side of the case to connect to the Wifi module.
External antenna


I mounted the TED ADS-B external antenna on the belly, just ahead of the leading edge of the horizontal stabilizer.  This location kept it far away from comm and transponder antennas, and gives it a pretty much unobstracted view of the ground in flight, in all directions.


Case Installed


The case is mounted behind the right side flap pushrod tube via a couple of 8-32 screws into rivnuts.  The USB power supply is mounted using a fabricated L bracket (0.063 stock) pop-riveted to the vertical surface behind the tube, and the RG400 cable connection routes into the center tunnel and back to the tailcone.  The wifi module plugs into the panel mount USB extension, placed on the cover panel so that it is relatively protected from feet and items placed in the foot well.


Cover Installed
The power outlet on the right includes a 12v socket and a USB dual outlet that can provide power to the iPad and/or charge a cell phone. 
Carpet Installed

The last step is to replace the carpet, which covers the Wifi module and protects it from damage and curious fingers.  Holes are cut in the carpet for access to the 12v and USB outlets.

Built-in Stratux Parts list and sources

Component
Link
Source
Price
Raspberry Pi 2 Model B Complete Starter Kit
with SD Card pre-loaded with Stratux Software. (Includes Wifi module)
http://www.vilros.com/rp2b-7-stratux.html
Vilros
69.99
3-D printed case free design download (I got dual band but single band or no antenna would also work)
http://www.thingiverse.com/thing:1019324
Thingverse
free
3-D online printing service:  (be sure to specify final size as 7.625" x 3.75" x 1.5", which is not the default)
https://www.makexyz.com/?frm=logo
MakeXYZ.com
50.80
NooElec NESDR Mini 2 SDR & DVB-T USB Stick (RTL2832 + R820T2) with Antenna
http://www.amazon.com/dp/B00P2UOU72/ref=cm_sw_su_dp Amazon
22.50
Mediabridge USB 2.0 - USB Extension Cable (6 Inches - two needed)
http://www.amazon.com/Mediabridge-USB-2-0-Extension-Gold-Plated/dp/B002KNI796?ie=UTF8&psc=1
&redirect=true&ref_=oh_aui_detailpage_o00_s00
Amazon
10.98
RF coax cable assembly BNC female to MCX male right angle 6''
http://www.amazon.com/coaxial-cable-assembly-female-right/dp/B00CSCTU40?ie=UTF8&psc=1
&redirect=true&ref_=oh_aui_detailpage_o00_s00
Amazon
5.00
PAC USB-DMA Dash-Mount Adaptor for USB Accessories (for Wifi module)
http://www.amazon.com/PAC-USB-DMA-Dash-Mount-Adaptor-Accessories/dp/B012PSPRR0?
ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00
Amazon
7.16
TED ADS-B external antenna
https://www.aircraftspruce.com/catalog/avpages/monopole11-13561.php
ACS
16.85
EA DUAL USB PANEL MOUNT CHARGING JACK
https://www.aircraftspruce.com/catalog/elpages/eadualusbpanel.php
ACS
24.95
13 ft. of RG400 cable, and 2 male BNC crimp on connectors

Various
about $55.


Total
263.23