I have an older EK 500 + SK 500, working off 9 volt, preliminary test shows better range compared with G2 transmitter/ receiver system. Does it sound right? or I have a defective G2 system?

Never used the older EK system. Look at the operating manual's specifications and note the RF power output. The G2/3 is 30mW, if the EK system is higher, that would be logical.
Many other variables can affect range though.

Never used the older EK system. Look at the operating manual's specifications and note the RF power output. The G2/3 is 30mW, if the EK system is higher, that would be logical.
Many other variables can affect range though.

The EK is a *receiver*, it does not transmit.

The transmitters of the G1 system, as far as I remember, are the same as the G2 and G3.

The newer SK 500 transmitters have switchable RF output levels of 10 or 30mW. The older AA versions were 30mW only I believe. I'm not sure about the oldest 9v versions.