- for FCC 915MHz it is 75mm
- for EU/LBT 868MHz it is 80mm
From time to time FrSky has a big problem with cutting their antennas to a correct length. Good thing, you can make your own TBS Crossfire RX antennas for cheap!
FrSky is not making things simple with R9 long range system. New firmware appears quite often and there is no way to flash receivers over the air. You can use some PC software, passthrough from FC and things like that, but from my perspective, as long as you can get to the receiver itself, the simplest way to flash R9 Slim and R9 Mini is to actually connect them to Taranis or Horus and do it from the radio itself. How? Like this!
When FrSky R9M long range transmitter and FrSky R9 receiver series started to pop up some time ago, there was a lot of speculations “it is any good?” “is it a Team Black Sheep Crossfire killer” “cheap Crossfire alternative?”. In time, new firmware started to appear, new receivers and so on. And oh yes, EU LBT version finally also appeared. And what… FrSky even was giving R9M for free with X10S Horus.
Details for halfwave dipole for an 868MHz band are quite simple:
Moxon antenna in layman terms, it’s probably a simplest linearly polarized directional antenna. It’s like a bent halfwave dipole with a bent reflector in a back. Think about it as a very simplified Yagi antenna. It does not have much gain but has very good backward rejection. And thank’s to a simplicity, Moxon is super easy to build at home. And I’m proud of radio carrying handle snap mount. I think I did a good job over here.
I’ve built mine with some 3D printed parts, 0.8mm copper welding wire, 22cm of RG174 coax and RP-SMA plug. And some glue of course! Result? It’s definitely directional 🙂 I’m not using it very often, but it’s small enough to be taken everywhere where I take my X10S.