HM Crux35 RxLoss at short range

[obtuse goblet]

RSSI dbm was still good, LQ dropped to 70 and then RxLoss occured. FC is HM X1 with SPI receiver. Antenna connection was good visually (don't know the internal though)
TX is RM TX12-II Internal Elrs.
The quad flew normally for 2 batteries, this happened at the 3rd battery. Between batt 2 and 3, PID tuning was modified, but I can't recall which one.
What could be the culprit?

[mighty shale]

do you have VTX Admin set to a band/channel?
what versions do these devices have?

[obtuse goblet]

Version 2.5.0

[mighty shale]

that's the TX.. what about the whoop?

have you tried this in a much faster packet rate?

[obtuse goblet]

The whoop is SPI RX, I haven't check the betaflight version

[obtuse goblet]

Does it matter? I mean, faster packet rate will decrease the sensitivity limit right?

[mighty shale]

I just want to know whether it happens in other packet rates/rf modes

[obtuse goblet]

Ok, will try with other rate tomorrow. It's 21 o'clock here 😁

[toxic raft]

Having failsafe issues with an ELRS SPI FC? A few possible causes:

1. Check antenna on FC for damage.
2. Go into the ELRS lua, select VTX Administrator, and make sure Band is set to Off.
3. Run the following commands in the CLI to help free up resources on the FC and prevent failsafes due to resource exhaustion:

set dshot_bitbang = off
feature -LED_STRIP
set cpu_overclock = 108MHZ
save

4. Make sure dynamic power is enabled in the ELRS lua to avoid overheating your TX
5. If your FC has an on-board VTX, run the minimum power you need and/or put VTX power on a switch so you can prevent the FC from overheating while the quad is stationary

[obtuse goblet]

Is there any issue regarding to VTX Admin in SPI FC?

[mighty shale]

there have been issues before that when vtx admin is set (Band is not Off), link drops happen

[obtuse goblet]

Only SPI FC or UART RX as well?

[mighty shale]

spi only

[obtuse goblet]

I see, I'll check it again

[deft token]

Xo offset is also more likely on an aio if they run hot