No radial Vertical

[lhk0pd]

I just recently bought a Jet Stream 680 vertical that they say needs no radials. It is a clone to the Comet 250B if that tells you any thing. And yes i know it is almost worthless on 75 meters and does poorly on 40 meters. I put radials on it and it seemed to help out but it is mounted on my Chain link fence about 5 feet from the ground. On the high bands it seems to at times out perform my dipole. But my question is should i raise it to the 10-15 feet elevation and higher and if so will it improve in signal an transmit. I ask this being as i heard that the comet 250 they suggest putting it at 33 ft they say for best results.