RF power level calibration

I am trying to re-calibrate my RF power meter, since the power meter resolution is 0.01dBm what kind of signal generator should I use ? most of the signal generator has output accuracy +-1dB or +-0.5dB only. and step attenuators also is in the +-1dB to +-0.5 dB accuracy range. did factory really calibrate the power meter with signal source of +-0.01dB accuracy before they ship the product out?

abc123,

Power meters "typically" have better accuracy as compared to signal generators. Many power meters have a test port that creates 50MHz @ 0dBm. What frequencies are you working at? Can you verify your signal generator with an O'Scope and then apply the signal to your power meter?

This is a chicken and egg problem, my RF power meter has the test port that creates 50MHz @ 0dBm reference, it can be used to re-calibrate the 0dBM point of the level for my power meter. but for other signal levels such as -25dBm, -45dBm,.. I need to use a step attenuator to attenuate the 0dBm reference signal to the level I want then use it to re-calibrate my meter at that specific signal level, or I can use a signal generator with accurate output level to re-calibrate the meter. the problem is the step attenuators or signal generators all has the output accuracy of +-1dB to +-0.5dB
how do I use it to re-calibrate my power meter@0.01dB level? the factory must have some way to do it!

the scope has the worst accuracy of signal level measurement.

Hi,
A test labor has to have calibrated sources, & their are regularly to control/recalibrate by acredited firms/labs...
Maybe you should buy so an "etalon"_valuable item.
I think you can try some calibration with DC/thermal powers too_thermistor/bolometry as detector...
K.