# RF Transmission Power Setting For 1W Variants
{% hint style="info" %}
Many countries have different legal RF power ratings. Be sure to operate within the legal limits.
Holybro SiK 1W Telemetry Radio default RF power is set to 21 dBm. Change the Tx Power based on your needs and the regulation limits.
{% endhint %}
Under the Tx Power drop-down menu, there are 21 power levels. But for SIK firmware, only 1, 2, 5, 8, 11, 14, 17, and 20 are valid. If you select an unsupported power value, the firmware will automatically select the valid power value closest to the selected value. For example, if you select 19, the firmware will automatically switch to 20.
Holybro SiK 1W Telemetry Radio adds a 10dB fixed gain amplifier outside the modulation chip, so the Tx Power + 10dB is the final transmission power. The corresponding relationship of the transmission power is as follows:
MissionPlanner value Actual RF power
1 -> 11dbm (12.5mw)
2 -> 12dbm (15.6mw)
5 -> 15dbm (31.25mw)
8 -> 18dbm (62.5mw)
11 -> 21dbm (125mw)
14 -> 24dbm (250mw)
17 -> 27dbm (500mw)
20 -> 30dbm（1000mw)
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