In order from best to worst on channel 7
RCA ANT751 Log-Yagi VHF Hi with UHF Folded Dipole
AntennaCraft G1483 4 Bay Gray Hoverman
Antennas Direct ClearStream1 Convertible, Proprietary Loop with reflector
Channel Master 4220 2 bay Bowtie
Heh, not too surprising a result, the ANT751, being the only vhf-hi antenna of the group, should have outperformed the others by a large margin on channel 7. The AntennaCraft G1483 should have a negative net gain on vhf-hi channel 7.
Since you have the best un-bent-up example of the G1483, could you post the dimensions of it ?
For the elements, I would need center of wire to center of wire measurements of : stub length, length of the legs (Assuming all the legs and stubs are the same length, correct ?) approx wire gauge or diameter of elements, and the distance between the elements (feedpoint distance) and the reflector to element distance.
For the reflector rods, I would need the center of rod to center of rod measurements of each of the split reflector rods (I assume they are split) and the gap distance, the vertical distance each rod to each other, and the diameter of the rods (it looks like common 3/8 inch stuff).
Is the boom 3/4 inch square or 1 inch square ? I would need a rough discription of the boom to element standoffs, distance at bottom and top (it looks like a 1/2 inch aluminum strip about 1/16 inch thick ?) Thanks.
If the G1483 is true to form with most of rest of the GH colinear rod models, then an addition of a 31.5 inch NAROD (Not A Reflector Or Director) should give you positive net gain on channels 7, 8, 9. Position a (youll need 2) 31.5 inch straight wire of similiar diameter as the element, exactly .5 inches center of wire to center of wire parallel and above the top stubs and below the bottom stubs. The wire is electrically isolated from any other part of the antenna, ie its free floating with just plastic strips holding it in place. A picture is better than describing, so when finished the G1483 should look something like this:
The compromise with the NAROD vhf-hi versions is about a .5 to 1.5 dbi less uhf gain, mostly with a gain dip in the channel 40 region.
For channels 10, 11, 12, 13 use a 28.0 inch NAROD length.
For channels 8,9,10 and a good compromise overall, use a 30.25 inch NAROD length.
For additional gain on channels 7,8,9 but harder and trickier to install, you could put a NAROD reflector 12.5 inches behind the NAROD. (For channels 10 to 13, the distance is 10 inches. For channels 8, 9, 10 the distance is 11.5 inches)