Ok, so here is Part 2 of the range checking.
This time I tested 4 Radios.
1. Spektrum DX6i with an AR6200 receiver
2. Futaba 6EX 2.4 ghz with a R606FS receiver
3. A Kraft Series 80 7C 40 Mhz FM (built in 1980 and last serviced in 1990)
4. A 36 Mhz FM 4 Channel radio that came packaged in an RTF Ducted Fan F-18 kit (it has a brand label of "FAMOUS" on it)
I removed the 36 mhz radio from the F-18 and replaced it with the Futaba 6EX which is fortunate as you will see..
With my wife sitting with the 4 transmitters in the location indicated in the photo below.
I used my mobile (cell) phone to instruct her which sticks to move so I could view the corresponding servo movement.
I then drove with the 4 receivers, with servos connected to the positiions indicated.
Position 1 - 1.6 Kilometers
Spektrum - Perfect connection and response
Futaba - Perfect connection and response
Kraft - Perfect connection and response
Famous - No connection, no response
Position 2 - 3.7 Kilometers
Spektrum - Perfect connection and response
Futaba - Perfect connection and response
Kraft - No connection, no response
Famous - No connection, no response
Position 3 - 5 Kilometers
Spektrum - Intermittent connection and response (If I held the receiver above my head it became fully connected and appeared to have reliable response, but when I lowered the RX it lost connection)
Futaba - Reasonable connection and response with intermittent red blinking on the RX light, however when I shield the antenna with my hand the connection dropped completely
Kraft - No Connection
Famouse - No Connection
I then drove back to the location of the transmitters.. The "Famous" Brand 36 mhz radio did not connect until I was within 450 meters of the transmitter (hardly what you would fly a ducted fan jet with ...)
So my conclusion....
Spektrum and Futaba 2.4 ghz were virtually on par for range and clearly superior to my Kraft radio that was state of the art in 1980 (40Mhz FM)
The 36 mhz FM radio was not even in the ballpark...
Hope you find this info useful..
Cheers...