Over the last few years I've set up a variety of FrSky transmitters and have got to know what to check out after purchase. So in this post, I list a few tips, including an effective method for checking range.
1. Check the gimbal wiring
The quality of FrSky hardware has improved steadily over the years. However one recurring complaint is the lack of proper support for the gimbal cables, which has in rare cases led to wires fracturing. So one of the first tasks is to open the case and check out the wiring at the pot or hall sensor.
Pay particular attention to the moving axis and if necessary apply some hot glue at the junction. I've done this on my own Horus and it's given me that extra bit peace of mind.
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| A dab of hot glue will help prevent fractures |
2. Check switch operation
Early X9Ds came with cheap switches which were nor particularly durable. The Plus has better switches, and those on the Plus SE are further improved.
Nevertheless, it's a good idea to check the switches on a new transmitter. This is easily accomplished in the Info menu, just cycle them back and forth and check that each position is correctly registered.
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| Info menu showing switch monitor panel |
If replacing a switch, note that the thread sizes and switch housing are different between the X9D, D+ and D+SE, so be sure to order the correct type.
3. Use the latest RF firmware
If flashing your RF firmware (e.g. from EU to non-EU), be sure to check the FrSky site for the latest firmware version. Watch out in particular for silent hardware changes. For example, if you have an X9D Plus which has been manufactured since November 2016, you must use the latest 2017 XJT firmware. The 2015 firmware will appear to work correctly but there will be a loss of range (as I discovered, see below).
4. Perform an RSSI check
The best way to check the range of a new transmitter is to compare it with another known working transmitter.
There are two ways we can measure the effective range. We can either record the range to achieve a certain RSSI value; or we can record the RSSI values at a certain range. The latter is easier to do, and is the basis for my method.
Whichever method you use, the transmitter should be in full range mode, not range test mode (we don't fly our models in range test mode!).
The first task is to make a receiver rig, see photos below. The same receiver should always be used (to avoid variation in the way RSSI is reported).
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| Test rig with spare receiver and battery. The servo is not necessary. |
Here's the procedure:
- Find an open space and choose two locations 150-200 meters apart. The precise distance is not critical.
- Ask your helper to hold the receiver rig at one end.
- Carry the 'reference' transmitter to the other end.
- Take a reading of the RSSI value from the transmitter's telemetry screen.
- Repeat with the second transmitter, using the same orientations for each device.
- Compare the RSSI values
Below are some test results with different devices, all made on the same day with tx and rx approximately 160 meters apart.
- Taranis X9D #1: RSSI = 69
- Taranis X9D #2: RSSI =69
- Taranis XJT ext module: RSSI =70
- Taranis X9DP #1
- 2015 firmware: RSSI = 52
- 2017 firmware: RSSI =72
- X9DP #2: RSSI =73
- Horus (internal antenna only): RSSI =69
Note how the method identified an issue on an X9DP transmitter. Turns out that the 2015 firmware was not fully compatible with the hardware. Flashing the 2017 firmware restored the range.
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