Turning an 827 into a Gainmaster style dipole

[Marconi]

Half wave dipoles won't give the same gain as a GM, the GM is a 5/8ths dipole.
I don't see anything special about the GM that would suggest that a different 5/8ths dipole couldn't match it. Electrically they would be very similar especially if you used the stub and cap tuning method.

Nav, I disagree, they aren't similar electrically. The vertical end fed type 5/8 wave radiator shows the bottom 1/8 wavelength to be out of phase with the top 1/2 wave radiator and that is not so with the GM's balanced design where the entire 5/8 radiator is in phase. The improved symmetry of the center fed GM alone should provide some noticeable difference between the two, to say nothing about the improved capture area. They are not alike, physically or electrically.

As a side note, my testing does not show nearly as much advantage for the GM as has been noted by other's making comparisons, excepting maybe Mr. Penn in the UK. That said however, I do see other advantages that are worth noting. I'm just waiting for some others to support my findings.