nicsure

RT900 Next TX Power System

Added 2025-05-07 08:10:11 +0000 UTC

Owing to the next level nastiness of the RT-900's TX circuitry it is next to impossible to have a nice ramp up of power like the H3 and 890 can do. You have to switch the PA Gain settings according to the power level which makes it impossible to come up with a system to calibrate every radio.

As a result the only real solution is to introduce power output stages. The stock firmware had Low/Mid/High but we can do better than that. I propose a 7 step output power step.

OFF (TX Disabled)
ZRO (Zero power, used for very close contact, such as a node or repeater near to you. Essentially the PA Gain is turned all the way down)
VLO (Very low power, probably on the order of 0.125 W maybe?)
LOW (Low power, maybe 0.5W or so?)
MID (3W ?)
HI (5W ?)
VHI (10W ?)

Obviously the 5 "real" power settings (VLO, LOW, MID, HI, VHI) will be calibratable via the SPI app but unfortunately, there will be no Watts output estimate anymore , sorry.