Lords, if you're saying that the GPK affects the receive only, then that would be pretty simple for any of us to check out. If you have ever made this comparison, one with and one without a GPK, you would know the answer and so would loosecannon that it is not possible to tell just by observations. Our human sense of hearing in this hobby is probably our best determining factor as to how our radios respond to changes or different products in line, yet we all tend to ignore what our ears tell us. Although in most cases it has nothing to do with our ears and I call it Meterites, a bad eye condition, where the eyes and the brain disconnect.
If loosecannon were to call and ask any of these guys, he still would likely not know the answer. Sure he would like to know the facts, but now at least he knows that others have speculated about these affects, TOA and the affects of an effective ground plane on a vertical antenna. Does it lower the TOA, improve the RX, improve the TX, improve the DX, improve the SWR, improve the gain, Improve all the above, make no difference, or what?
I like 1/4 wave ground planes and I have done a lot of my own ideas in experimenting on mine. The 1/4 wave is one antenna that right out of the box will demonstrate much of the truth about the affects and theory of Ground Planes. But, even so I still have never been able to determine the TOA and to tell what happens to it when I add radials or change the angle.
As far as SWR goes using a GPK on one of these CB antennas or not, I have found that adding a GPK to the A99 only seemed to narrow the bandwidth. It made a nice curve rather than an almost flat line, and maybe the SWR rise a bit, a big no-no for those with Meterites. So with that result I figured it was helping a bit even though I could not really detect anything with my radio meter, my SWR meter, my eyes, my ears, or my buddies who checked my signal.
I have not tried this with the Maco V5/8, but I do have an antenna made by Wolf radio that is very similar except it is a 1/2 wavelength and looks like the old Ringo, it does not have a ground plane attached. Performance wise it works very well, but the SWR is difficult to control and keep very low unless you are able to tune at installed height. When the antenna is moved up or down very much, the SWR changes, so I guess the match is also changing due to the changing relationship with the earth and maybe if it had a good GP that would not happen. If you have meterites, you would not like this one.
It is true you should not and cannot believe everything that you read, but what you read sometimes can get you to thinking and that is not always bad. If loosecannon did call he probably won't get much better suggestions to consider. So, with all that said, I guess it is possible that the presence of a GPK will really make a big difference with a 5/8 or .64 wavelength antenna, but I still doubt it affects the TOA very much if any.
There is another forum out there that sells these antennas on their Website. Some there will tell you all day long, among other things, that the GPK add-on will lower your TOA down and give you an S3-S4 signal improvement in gain on the horizon if installed according to their Tech Tip. Check it out.
