gsm tdma power
You could try using a diode detector.
Pad down the output of your TX to about 0dBm or so, note the output level during the TX pulse, then substitute a cw signal to give you the same diode voltage, then measur e the cw signal with a power meter.
You may have to take into account any ampliude modulation on the carrier and the accuracy of the pad, but it will give you a rough and ready measurement without having to spend a lot on a new power meter.
Peter