Here's what the [manufacturer of the chip (CC1101) says](https://e2e.ti.com/support/wireless-connectivity/sub-1-ghz-group/sub-1-ghz/f/sub-1-ghz-forum/1120743/cc1101-operation-outside-datasheet-frequencies/4154832) about going outside the limits:
```
The frequency range of the chip is always tested in the verification tests and there is always some design margin included before
the VCO and/or PLL has problems operating for a specified frequency range. Working outside the frequency range can cause issues
with the VCO and/or PLL and/or divider not operating correctly. If the VCO is operating outside it's standard frequency range,
there are risks of unwanted emissions and no oscillation. The PLL can also fail to lock if operating outside it's standard
frequency range and will still apply power to the antenna.
Risks with antenna mismatch are increased harmonics, reduced output power and increased current consumption. Generally, the antenna
mismatch can be large and the output stage will not be damaged when presented with a large mismatch for short periods of time.
However, if the antenna mismatch is very poor for long periods of time, then this can effect the longevity of the chip especially
if further stressed with maximum voltage and maximum temperature. Recommend keeping VSWR better than 5:1 for worst case scenarios.
You'll need to edit some code and recompile if you want to break outside of the officially supported frequencies. [Proceed with caution.](https://github.com/UberGuidoZ/Flipper/blob/main/Sub-GHz/Restaurant_Pagers/SubGHz_changes.md)
