[werk_ag]

I have setup the TX to send only one type of data at the time:
- with only the temp/humidity, I see the LED blinking every 25 sec or so,
- with only the wind sensor, the blinking happens every 5 sec or so,
- with only the rain, it's every 30 sec.
So looks like we are good wit the TX board.

When running in test mode, the RX LED is constantly off; while in standard mode, it's always ON (supposed to be blinking, right? i dont remember).
I can see the TX LED of the RX board blinking as well.

This shows that is the reading of the weather instruments is not blocking the system. Thanks for having tested it.
Surely the problem is with the transmitter module.
The TX LED blinking just means that the TX module is powered before it needs to send a packet, and switched off after sending it.

I had a faulty transmitter once. I found that it would work sometimes if I touched the coil and it's connections.

The FS1000A is a good and powerful transmitter module, but it's very easy to make it not working. The coils are part of the oscillating circuit, if you inadvertently change them, by changing the space between turns, of even having a metal part close to the coils, it stops to oscillate and don't transmit anything. This was the main reason why some time ago I changed the design to use the KDX-10036 module, which don't have any coils.

As you said, sometimes touching the coils adds some capacitance to the circuit and makes it start to oscillate again. This FS1000A behaviour is widely described in several posts especially in RF forums.