I use to have one of those Super mag type 1/2 wavelength antennas, many years ago. I won it at the local CB
Break. I had in a box for some time and then I put it up and worked reasonable well. I did not measure the antennas gain, but I think it worked better than most none ground plane antennas.
The Super Mag uses a coil as the impedance matching device, and I agree with JPT with the 500 watt rating. Maybe even a even 1000 watts but no more.
I used the Super Mag Antenna as a vertical with a Moonraker 4 element beam, that was about 50 foot away. They worked well as in those days we didn't have anything better. Before all this I went down to Buddy Sales in Reseda California in the San Fernando Valley, and they no longer could get the Hy-Gain Penetrator 500....#@%$*& And those who had the Penetrator 500 would not sell them.
So it is not a waste of time to install the Super Mag Antenna, if you have it there in a box. The ground plane radials may break off after a few years in strong winds, but not everyone has the strong Santa Ana Winds we have here in the Southern California. While back in Georgia and North Carolina last year I saw a few Super Mag antennas still up and in one piece.
My Super Mag Antenna broke at the Base Plastic Insulator, exposing the matching coil. The vertical antenna element was now at a 45 degree angle and the SWR went up some. So if you put this antenna up you will need to protect the Base Insulator Plastic with black tape or paint to last longer. Or replace it with some heavy walled Gray PVC Pipe. The Gray PVC Plastic Pipe is made to take the suns UV rays and last, but I would paint it anyway.
Good luck with the Super Mag Antenna.
Jay in the Mojave