Newbie here, needing help with the SX1231 basics. (aka RFM69HCW) I can't seem to get anything out the antenna, although I can read and write the registers. I'm using RasPi3 and RFM69 driven by LM3940 5V TO 3V regulator. What am I missing?

#intended for testing transmitter with spectrum analyzer
import spidev
import time
SPI_BUS = 0
SPI_SS = 0
SPI_CLOCK = 2000000 #Mhz
spi = spidev.SpiDev(SPI_BUS, SPI_SS)
spi.max_speed_hz = SPI_CLOCK
i = 1
rx = spi.xfer([0x81,0x0c]) #set TX mode
while True:
rx = spi.xfer([0x80,0x55]) #address and data
time.sleep(1)
print(i)
i = i+1
spi.close()