ServoCity has been selling pan/tilt servo components that you can use to make an antenna tracker for some time. Recently, ServoCity released new ‘tube gear boxes’ which can be combined with a previous gear box to create one of the strongest and most precise antenna tracking assemblies available. This system does come at a “pro” price, but is strong enough to move anything from a single patch antenna to 3 Yagis at once (see below). Thanks to Roel-CP for posting his 3 Yagi build, which was the impetus for this review.
In our review, we are using the following gear to build this antenna tracker:
- Antenna Tracking Controller: ImmersionRC EzTracker with the latest firmware version 1.10.
- ServoCity Components to build the tracker (see below)
- Antenna: Large 19db Patch Antenna
- A specially manufactured bracket to mount our patch antenna to the assembly’s aluminum bracket (see below)
You can buy the components individually from ServoCity and build the assembly yourself or, for an additional $60, have ServoCity put this together for you. Our review unit came fully assembled by ServoCity, which was a nice surprise. The overall assembly is super strong and light. The movement of the antennas using this assembly is precise and free of any wobble or ‘play’.
Components from ServoCity
To build this assembly, you will need the following parts from ServoCity.
| Part Number | Qty | Description |
|---|---|---|
| SPG785A-BM | 1 | Servo Gearbox (3:1 Ratio) |
| SPG785A-5.0 | 1 | 785 Servo Power Tube Gearbox-5.0 (8.6:1 Ratio, Metal Gears) |
| 33785S | 2 | HS-785HB Servo |
| ALM-90-2.00 | 1 | 90 degree 2.00" Aluminum Mounting Plate |
| 90272A126 | 8 | 5-40x3/8" Pan Head Phillips Machine Screws |
| ECM-125-75 | 1 | End Cap Mount for 1" x 1.5" Extrusion |
Preparation
The pre-assembled gear boxes from ServoCity look like this.
It’s easy to see why this assembly is so sturdy. All parts are strong yet light aluminum. The pan gear box uses plastic gears, the tilt gear box uses metal gears. We will mount this assembly on top of the fpvmanuals lexan ground station, which has a flat top that is perfect for the way the pan gear box needs to be mounted.
The assembly comes with a right angled, aluminum bracket that you will use to attach your antenna(s) to. First, take this bracket off. You will re-install it when you have centered the servos, set up the EzTracker, and mounted your antennas to the right angle bracket.
Center the Servos
The first step is to center the servos. You can center the servos by connecting them to the EzTracker and power it on. While the EzTracker loads its settings it sets the servos to its programed ’0′ position. This will also be the servo centers so we won’t need off-sets later-on. Simply power on the EzTracker, leve it on for a few seconds and disconnect it again. With the servos centered, remove the gears attached to the servos so that you can freely move the pan and tilt direction.
Manually move the servos so that the antennas would point straight ahead and horizontally at the horizon. Now, re-install the servo gears.
Settings for the EzTracker Controller
| Option | Setting |
|---|---|
| Pan us/360 | 680 |
| Tilt us/360 | 1940 |
| Tilt max | 90 |
| Tilt min | 0 |
| Pan min | -180 (but could be less if your antennas bind with the tracker assembly) |
| Pan max | 180 (but could be less if your antennas bind with the tracker assembly) |
| Tilt offset | +3 |
| Pan rev | Yes |
| Tilt rev | No |
| Servospeed | 1 |
Mounting and Wiring Antenna(s)
The strength of this assembly allows for a diverse set of antenna options from single patch antenna to dual patch or multiple Yagis. To mount an antenna will require you to create a mounting bracket that holds your antennas and mounts to the aluminum bracket included in the assembly. It all depends on what you need.
Single Patch Antenna
To mount a single patch antenna requires a mounting plate that has the appropriate holes for your patch antenna. We’ve created a mounting plate design to mount your patch antenna to the black aluminum bracket that comes with the assembly from ServoCity.
Custom laser cut bracket to mount patch antenna
You can order this bracket from Ponoko.com which will laser cut this bracket for you. We suggest you make this bracket in 3.0mm acrylic material, but you can choose from a variety of other materials and thicknesses. Our design includes 2 brackets. One bracket has mounting holes for a patch antenna with mounting bolts that are 50mm apart. If your patch antenna has differently spaced bolts, the 2nd bracket has no pre-made holes and instead shows guiding lines so that you can drill your own holes. You can also download the EPS file and modify the holes to match your patch antenna perfectly.
Download the eps or order the bracket
Mounting bracket for patch antenna.
The hubs used on this assembly are hollow, this enables you to route your antenna wire through the hub if you’re using RG-316 or similarly thin cabling.
The hollow hubs allow you to route servo and antenna wires.
Multi Yagi Antenna Set-Up
Roel-CP has created a mounting solution that holds 3 Yagi antennas. It’s an inverted aluminum “U” bracket that has antennas on each side of the U.
"Inverted U" aluminum bracket to hold multiple Yagi antennas.
Here it is in action.
Conclusion
The strong and light build of this assembly makes it well suited for antenna tracking applications. The hollow hubs also help to clean up the wiring if you’re using a single patch antenna. Not having wires stick out with lots of room/slack while the antenna rotates is a real plus. Please post comments and questions below.
